Biomedical subjects

I Lee

Publications and source records attributed to I Lee.

At least 91 records · Page 5Linked to original sources

PubMed1999

The Arabidopsis flowering-time gene LUMINIDEPENDENS is expressed primarily in regions of cell proliferation and encodes a nuclear protein that regulates LEAFY expression.

Mutations in the LUMINIDEPENDENS (LD) gene of Arabidopsis thaliana (L.) Heynh. (Arabidopsis) confer a late-flowering phenotype, indicating that LD normally functions to promote the floral transition. RNA and protein blot analyses, along with the analysis of transgenic plants containing a fusion between a genomic fragment of LD and the reporter gene uidA (GUS), indicate that LD is expressed primarily ipical proliferative regions of the shoot and root, including the shoot apical meristem and leaf primordia. Subcellular localization studies indicate that LD is a nuclear protein, consistent with its previously proposed transcriptional regulatory role. We have also found that in an apetala1 cauliflower (ap1 cal) background the ld mutation converts the reproductive shoot apex to a more vegetative state, a phenotype that is similar to that seen for the leafy (lfy) mutant. Furthermore, in situ hybridization analysis indicates that LFY levels are drastically reduced at the apex of ld ap1 cal plants after bolting. These data are consistent with the idea that at least one function of LD is to participate in the regulation of LFY.

Arabidopsis↗

PubMed1999

Morphological and biochemical analysis of anti-nuclear matrix protein antibodies in human sera.

Autoimmune sera have been used in the diagnosis of autoimmune diseases as well as the analysis of nuclear substructures. In an attempt to study the biological characteristics of the nuclear matrix, we screened human sera using immunofluorescent staining and immunoblot. We detected antibodies against nuclear matrix (NM), a remnant nonchromatin protein compartment after the treatment of detergent, salt and nuclease, in 212 out of 284 tested sera (74.6%) by immunoblot. Peptides with molecular weights of 70 kDa, 50 kDa and 25 kDa were detected in the order of frequency. Clinical informations of 198 out of 212 cases were available and went as follows: 38 cases were autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis; 132 non-autoimmune and non-neoplastic diseases; 16 neoplastic diseases and 12 cases unclassified. The immunofluorescent staining intensity by anti-nuclear matrix protein (NMP) antibodies decreased variably, but fibrillogranular, speckled and nucleolar immunolocalization patterns were retained after in situ fractionation. Ku70 and La protein were detected by anti-NMP antibodies. Immunolocalization by anti-NMP antibodies indicates that the NMPs constitute a variety of characteristic nuclear substructures and may serve as autoantigens in diverse human diseases. In addition, the presence of Ku70 and La protein as NMPs suggests that the NM can be functionally active in association with DNA or RNA.

Antigens, Nuclear↗

PubMed1999

The first imported case of pulmonary coccidioidomycosis in Korea.

Coccidioidomycosis is an endemic disease found in the southwestern part of North America. Travellers who visit the endemic area may carry the infection. We report a case of pulmonary coccidioidomycosis in a 74-year-old woman. She was healthy before visiting Arizona, U.S.A twice. After returning home, she began to complain of intermittent dry coughing. The symptom was mild, however, and she was treated symptomatically. Later a chest radiograph, which was taken 4 years after the onset of the symptom, showed a solitary pulmonary nodule in the right upper lobe. By percutaneous needle aspiration, a few clusters of atypical cells were noted in the necrotic background. A right upper and middle lobectomy was done. A 1.5 x 1.5 x 1.2 cm sized tan nodule was present in otherwise normal lung parenchyma. Microscopically, the nodule consisted of aggregates of multiple solid granulomas inside of which was mostly necrotic. Neutrophils and nuclear debris were scattered along the periphery of the necrotic foci. Numerous multinucleated giant cells were associated with the granulomas. In the necrotic area, mature spherules of Coccidioides immitis, which were 30-100 microm in diameter, were present. They contained numerous endospores which ranged from 5 to 15 microm and were also noted in multinucleated giant cells. The diagnosis of coccidioidomycosis was made. She is doing well after the resection.

Aged↗

PubMed1999

Dynamic redistribution of nuclear matrix proteins by adenovirus infection.

We analyzed the redistribution of nuclear proteins, PML protein, Ku70/Ku80, a putative spliceosome associated protein, pNMM102 and a nucleolar proliferating antigen, p120 after adenovirus 5 (Ad5) infection using immunofluorescent staining. These proteins remained after in situ fractionation. PML was located at irregular bars 6 h after infection from fine dots of uninfected cells. Distribution pattern of PML was not changed throughout the course of infection. Internal nuclear matrix network composed of Ku protein became much coarser in interphase cells at 12 h after infection. Ku protein was clumped at 18 h after infection, where EIA protein was colocalized. Speckles and interconnecting fibrils recognized by monoclonal antibody NMM102 disappeared early after infection, and reappeared at 18 h after infection in various patterns. The number and staining intensity of p120 containing domains increased markedly in early replication phase, and their shape became irregular with a few fine dots. A few Ad5 infected cells revealed diffuse nucleoplasmic as well as nucleolar p120 in late replication phase. Redistribution of four different nuclear matrix proteins by Ad5 infection indicates that the nuclear matrix is dynamically involved in gene expression.

Adenoviridae Infections↗

PubMed1999

A path analysis of self-care of elderly women in a rural area of southern Taiwan.

For rural elderly women in Taiwan, in addition to poor economic situations and limited health resources, changing traditional roles and responsibilities and changing family structures further aggravate their conditions of health. Self-care was considered as a strategy or a form of coping to enhance the health and quality of life of these women during their aging process. To design an effective health-promotion program for elderly women, therefore, understanding their self-care model is important for health care professionals. The purpose was to use a path analysis to test a model of self-care in predicting the direct and indirect effects of selected key variables on self-care among rural elderly women. A non-experimental, cross-sectional study was designed to test the proposed hypotheses and the paths in a causal model of self-care. Of the 200 elderly women invited to participate, 192 completed all interview questions. The proposed causal model was tested with a path analysis, using the LISREL 8 program. The resultant model showed that the chi square was 3.65 with four degrees of freedom. The p-value for the resultant model was 0.46, revealing that the model fit the data and it was, therefore, retained. In addition to the chi 2 test, other fit indices also indicate the model fit the data well. In the resultant model, 56.0% of the total variance in self-care was accounted for by age, socioeconomic status, perceived health status, and social support (p < 0.001); 16.4% of the total variance in social support was accounted for by age, socioeconomic status, and marital status (p < .001); and 7.3% of the total variance in perceived health status was accounted for by social support (p < .001). The implications of nursing practice and research were discussed based on the findings.

Aged↗

PubMed1999

Analysis of referral initiatives, severity of illness and return to care of older women with cervical cancer.

BACKGROUND: Cervical cancer is a worldwide malignancy particularly prevalent in older women. Due to the increasing population ratio of older women and their more complicated illnesses, doctors in Taiwan are concerned about the care of older patients with cervical cancer. Few studies have been performed on the association between referral initiative and illness severity upon referral as well as the tendency of older patients with cervical cancer to return to the referring doctor and to the consultant at the medical center for follow-up. The purpose of this study was to investigate the referral association by adjusting for confounding variables. METHODS: This study included 214 women aged 65 years and over with cervical cancer diagnosed between 1987 and 1995. Patients were referred to a tertiary teaching hospital by 71 primary care gynecologists. The International Federation of Gynecology and Obstetrics clinical stage and clinical severity were assessed in each patient. Histopathologic results were reviewed to confirm the diagnosis. RESULTS: Of all the cervical cancer referrals, 20.2% were initiated by patients or families and 79.8% were initiated by primary care doctors. No statistically significant differences were found in the Basic Activities of Daily Living or Instrumental Activities of Daily Living between doctor- and patient-initiated referrals. High Geriatric Depression Scale and low Mini-Mental State Examination were associated with doctor-initiated referrals. Higher cancer stage and greater clinical severity of patients with cervical cancer was found in patient- rather than doctor-initiated referrals. After adjusting for marriage, family type, medical payment, mental status, cancer stage and clinical severity, the data showed that, if the referral was initiated by a primary care doctor, older patients with cervical cancer had a similar likelihood to return to both the primary care doctor and the tertiary teaching hospital for follow-up. CONCLUSIONS: If a referral was initiated by a doctor, older women with cervical cancer were not only likely to return to their consulting physician at the medical center, but also likely to return to their primary care doctor. Continuous care is more likely to occur when the primary care doctor initiated the referral.

Aged↗

PubMed1999

The effect of various therapeutic solutions including colloidal chromic 32P via an intratumoral injection on the tumor physiological parameters of AsPC-1 human pancreatic tumor xenografts in nude mice.

To overcome the physiological barrier in solid tumors (i.e., tumor hypertension), a large volume of material is required via an intratumoral injection. Alternatively, a method of reduction in tumor hypertension is also feasible. In this study, we focused on the physiological response after an intratumoral infusion of various therapeutic agents. Tumor interstitial fluid pressure (TIFP) was intermittently monitored for up to 7 days after treatment using AsPC-1 human pancreatic tumors in nude mice. Macroaggregated albumin (MAA), colloidal chromic 32P (32P-CP), albumin, dexamethasone, 5-fluoro-2'deoxyuridine, dextrose, saline, and trypan blue increased TIFP within approximately 5 min, and TIFP returned to the original level within 1 h, except in the case of MAA and 32P-CP. We also found that the maximal uptake for AsPC-1 tumors in both the exponential and plateau growth phases occurred at approximately 100 min postincubation; the maximum value in the exponential growth phase was approximately 2 times less than that of plateau growth phase (P < 0.01). Therefore, this study supports intralesional 32P-CP brachytherapy for nonresectional pancreatic cancer patients. This may offer a promising treatment modality for delivering high doses of tumor-selective radiation, mainly due to two physiological mechanisms: (a) the high adherence of 32P-CP to the infused regions; and (b) reduction in either tumor blood flow or TIFP by this therapeutic colloid.

Animals↗

PubMed1999

[Geobotanical studies on the island of Tanegashima (affinity of world property island Yakushima)].

A list was drawn up of wild plants growing on Tanegashiama island that were identified in our field work, and the list was compared with the flora of the rest of Japan and the flora of Taiwan. There were 166 families and 1,218 species consisting of 23 families and 159 species of Pteridophyta, 4 families and 7 species of Gymnosperma, 113 families and 700 species of the dicotyledous Angiosperma, and 26 families and 353 species of monocotyledous Angiosperma. There are 229 families and 5,500 species of plants in Japan, 196 families and 3,019 species in Kyushu, and 228 families and 3,477 species in Taiwan. There are 11 species of endemic plants on Tanegashima and Yakushima, and the best known of them is Pinus armandii Francht. var. amamiana Hatsushima. There are 181 species of flora of flora limited to the northern element, including several important medicinal plants, such as Akebia quinata Decaisne and Zanthoxylum piperitum DC. The 69 species of flora limited to the southern element include several important tropical plants, such as Messerschmidia argentea Johnston and Clerodendrum inerme Gaertn. Most of these plants are distributed on both island, but some of are distributed only Tanegashima. We concluded that one of the temperate borderlines of Japanese flora in the temperate zone is the islands of Tokara. The flora of Tanegashima and Yakushima are having a closely affinity of plant species and having the rich plant species.

Botany↗

PubMed1998

A genetic framework for floral patterning.

The initial steps of flower development involve two classes of consecutively acting regulatory genes. Meristem-identity genes, which act early to control the initiation of flowers, are expressed throughout the incipient floral primordium. Homeotic genes, which act later to specify the identity of individual floral organs, are expressed in distinct domains within the flower. The link between the two classes of genes has remained unknown so far. Here we show that the meristem-identity gene LEAFY has a role in controlling homeotic genes that is separable from its role in specifying floral fate. On the basis of our observation that LEAFY activates different homeotic genes through distinct mechanisms, we propose a genetic framework for the control of floral patterning.

AGAMOUS Protein, Arabidopsis↗

PubMed1998

Active site topology of artificial peroxidase-like hemoproteins based on antibodies constructed from a specifically designed ortho-carboxy-substituted tetraarylporphyrin.

The topology of the binding site has been studied for two monoclonal antibodies 13G10 and 14H7, elicited against iron(III)-alpha,alpha,alpha,beta-meso-tetrakis(ortho-carboxyphenyl)porph yrin [alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin]], and which exhibit in the presence of this alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] cofactor a peroxidase activity. A comparison of the dissociation constants of the complexes of 13G10 and 14H7 with various tetra-aryl-substituted porphyrin has shown that: (a) the central iron(III) atom of alpha,alpha,alpha,beta-Fe[(o-COOHPh)4-porphyrin] is not recognized by either of the two antibodies; and (b) the ortho-carboxylate substituents of the meso-phenyl rings of alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] are essential for the recognition of the porphyrin by 13G10 and 14H7. Measurement of the dissociation constants for the complexes of 13G10 and 14H7 with the four atropoisomers of (o-COOHPh)4-porphyrinH2 as well as mono- and di-ortho-carboxyphenyl-substituted porphyrins suggests that the three carboxylates in the alpha, alpha, beta position are recognized by both 13G10 and 14H7 with the two in the alpha, beta positions more strongly bound to the antibody protein. Accordingly, the topology of the active site of 13G10 and 14H7 has roughly two-thirds of the alpha,alpha,alpha,beta-Fe[(o-COOHPh)4-porphyrin] cofactor inserted into the binding site of the antibodies, with one of the aryl ring remaining outside. Three of the carboxylates are bound to the protein but no amino acid residue acts as an axial ligand to the iron atom. Chemical modification of lysine, histidine, tryptophan and arginine residues has shown that only modification of arginine residues causes a decrease in both the binding of alpha,alpha,alpha, beta-Fe[(o-COOHPh)4-porphyrin] and the peroxidase activity of both antibodies. Consequently, at least one of the carboxylates of the hapten is bound to an arginine residue and no amino acids such as lysine, histidine or tryptophan participate in the catalysis of the heterolytic cleavage of the O-O bond of H2O2. In addition, the amino acid sequence of both antibodies not only reveals the presence of arginine residues, which could be those involved in the binding of the carboxylates of the hapten, but also the presence of several amino acids in the complementary determining regions which could bind other carboxylates through a network of H bonds.

Amino Acid Sequence↗

PubMed1998

A single amino acid change in the acetylcholinesterase-like domain of thyroglobulin causes congenital goiter with hypothyroidism in the cog/cog mouse: a model of human endoplasmic reticulum storage diseases.

Newly synthesized thyroglobulin (Tg), the major secretory glycoprotein of the thyroid gland, folds and homodimerizes in the endoplasmic reticulum (ER) before its export to the site of iodination, where it serves as the precursor for thyroid hormone synthesis. In families with defective Tg export, affected individuals suffer from a thyroidal ER storage disease characterized by a distended thyrocyte ER containing misfolded Tg, along with induced ER molecular chaperones. Inherited as an autosomal recessive trait, deficient Tg causes congenital hypothyroidism in newborns that, if untreated, results in goiter along with serious cognitive and growth defects. Recently, a similar phenotype has been observed in inbred cog/cog mice, although the precise molecular defect has remained undefined. Here, we have isolated and cloned a full-length 8.5-kb Tg cDNA from cog/cog mice and unaffected isogenic AKR/J mice. Comparison of the complete sequences reveals that cog/cog mice express a Leu-2263 --> Pro missense mutation in the acetylcholinesterase-homology domain of Tg. Heterologous expression studies in COS cells indicate that cog Tg exhibits a severe defect in exit from the ER. Site-directed mutagenesis of cog Tg to convert the single amino acid back to Leu-2263 restores normal Tg secretion. We conclude that the cog mutation in Tg is responsible for this ER storage disease that causes thyroid dyshormonogenesis.

Acetylcholinesterase↗

PubMed1998

Molecular cloning, chromosomal localization, tissue distribution, and functional expression of the human pancreatic sodium bicarbonate cotransporter.

We report the cloning, sequence analysis, tissue distribution, functional expression, and chromosomal localization of the human pancreatic sodium bicarbonate cotransport protein (pancreatic NBC (pNBC)). The transporter was identified by searching the human expressed sequence tag data base. An I.M.A.G.E. clone W39298 was identified, and a polymerase chain reaction probe was generated to screen a human pancreas cDNA library. pNBC encodes a 1079-residue polypeptide that differs at the N terminus from the recently cloned human sodium bicarbonate cotransporter isolated from kidney (kNBC) (Burnham, C. E., Amlal, H., Wang, Z., Shull, G. E., and Soleimani, M. (1997) J. Biol. Chem. 272, 19111-19114). Northern blot analysis using a probe specific for the N terminus of pNBC revealed an approximately 7.7-kilobase transcript expressed predominantly in pancreas, with less expression in kidney, brain, liver, prostate, colon, stomach, thyroid, and spinal chord. In contrast, a probe to the unique 5' region of kNBC detected an approximately 7.6-kilobase transcript only in the kidney. In situ hybridization studies in pancreas revealed expression in the acini and ductal cells. The gene was mapped to chromosome 4q21 using fluorescent in situ hybridization. Expression of pNBC in Xenopus laevis oocytes induced sodium bicarbonate cotransport. These data demonstrate that pNBC encodes the sodium bicarbonate cotransporter in the mammalian pancreas. pNBC is also expressed at a lower level in several other organs, whereas kNBC is expressed uniquely in kidney.

Amino Acid Sequence↗

PubMed1998

Identification of the principal proteoglycan-binding site in LDL. A single-point mutation in apo-B100 severely affects proteoglycan interaction without affecting LDL receptor binding.

The subendothelial retention of LDLs through their interaction with proteoglycans has been proposed to be a key process in the pathogenesis of atherosclerosis. In vitro studies have identified eight clusters of basic amino acids in delipidated apo-B100, the protein moiety of LDL, that bind the negatively charged proteoglycans. To determine which of these sites is functional on the surface of LDL particles, we analyzed the proteoglycan-binding activity of recombinant human LDL isolated from transgenic mice. Substitution of neutral amino acids for the basic amino acids residues in site B (residues 3359-3369) abolished both the receptor-binding and the proteoglycan-binding activities of the recombinant LDL. Chemical modification of the remaining basic residues caused only a marginal further reduction in proteoglycan binding, indicating that site B is the primary proteoglycan-binding site of LDL. Although site B was essential for normal receptor-binding and proteoglycan-binding activities, these activities could be separated in recombinant LDL containing single-point mutation. Recombinant LDL with a K3363E mutation, in which a glutamic acid had been inserted into the basic cluster RKR in site B, had normal receptor binding but interacted defectively with proteoglycans; in contrast, another mutant LDL, R3500Q, displayed defective receptor binding but interacted normally with proteoglycans. LDL with normal receptor-binding activity but with severely impaired proteoglycan binding will be a unique resource for analyzing the importance of LDL- proteoglycan interaction in atherogenesis. If the subendothelial retention of LDL by proteoglycans is the initial event in early atherosclerosis, then LDL with defective proteoglycan binding may have little or no atherogenic potential.

Amino Acid Substitution↗

PubMed1998

A cell cycle-regulated adenine DNA methyltransferase from Caulobacter crescentus processively methylates GANTC sites on hemimethylated DNA.

The kinetic properties of an adenine DNA methyltransferase involved in cell cycle regulation of Caulobacter crescentus have been elucidated by using defined unmethylated or hemimethylated DNA (DNAHM) substrates. Catalytic efficiency is significantly enhanced with a DNAHM substrate. Biphasic kinetic behavior during methyl incorporation is observed when unmethylated or DNAHM substrates are used, indicating that a step after chemistry limits enzyme turnover and is most likely the release of enzyme from methylated DNA product. The enzyme is thermally inactivated at 30 degrees C within 20 min; this process is substantially decreased in the presence of saturating concentrations of DNAHM, suggesting that the enzyme preferentially binds DNA before S-adenosylmethionine. The activity of the enzyme shows an unusual sensitivity to salt levels, apparently dissociating more rapidly from methylated DNA product as the salt level is decreased. The enzyme acts processively during methylation of specific DNA sequences, indicating a preferred order of product release in which S-adenosylhomocysteine is released from enzyme before fully methylated DNA. The kinetic behavior and activity of the enzyme are consistent with the temporal constraints during the cell cycle-regulated methylation of newly replicated chromosomal DNA.

Caulobacter crescentus↗

PubMed1998

Identification of the low density lipoprotein receptor-binding site in apolipoprotein B100 and the modulation of its binding activity by the carboxyl terminus in familial defective apo-B100.

Familial defective apolipoprotein B100 (FDB) is caused by a mutation of apo-B100 (R3500Q) that disrupts the receptor binding of low density lipoproteins (LDL), which leads to hypercholesterolemia and premature atherosclerosis. In this study, mutant forms of human apo-B were expressed in transgenic mice, and the resulting human recombinant LDL were purified and tested for their receptor-binding activity. Site-directed mutagenesis and other evidence indicated that Site B (amino acids 3,359-3,369) binds to the LDL receptor and that arginine-3,500 is not directly involved in receptor binding. The carboxyl-terminal 20% of apo-B100 is necessary for the R3500Q mutation to disrupt receptor binding, since removal of the carboxyl terminus in FDB LDL results in normal receptor-binding activity. Similarly, removal of the carboxyl terminus of apo-B100 on receptor-inactive VLDL dramatically increases apo-B-mediated receptor-binding activity. We propose that the carboxyl terminus normally functions to inhibit the interaction of apo-B100 VLDL with the LDL receptor, but after the conversion of triglyceride-rich VLDL to smaller cholesterol-rich LDL, arginine-3,500 interacts with the carboxyl terminus, permitting normal interaction between LDL and its receptor. Moreover, the loss of arginine at this site destabilizes this interaction, resulting in receptor-binding defective LDL.

Animals↗

PubMed1998

Phylogenetic analysis of the nef gene reveals a distinctive monophyletic clade in Korean HIV-1 cases.

To study the genetic variation of the HIV-1 strains prevalent in South Korea, we analyzed the nef sequences derived from 46 HIV-1-positive individuals living in various geographic regions in Korea. Phylogenetic analysis revealed four subtypes of HIV-1: A (3 patients), B (41 patients), D (1 patient), and a type that could not be clearly classified to any known subtype (1 patient). Thirty-five of the 41 Korean subtype B isolates formed a distinct monophyletic clade that is not related to any of the international sequences from the Los Alamos Database or GenBank as of June 1997. Indeed, the presence of unique conserved sequences was identified among the Korean isolates in this Korean subtype B group. The variations in the nucleotide sequences of a majority (32 of 35) subtype B samples within the Korean clade were 1.9% to 8.8%, and amino acid sequences varied from 3.9% to 15.5%. These results suggest that HIV-1 strains currently present in South Korea might have originated from a few sources or might be developing through a certain selective pressure. This is the first report on the molecular nature of the HIV-1 infection present in South Korea.

Adolescent↗

PubMed1998

NMR studies of internal dynamics of serine proteinase protein inhibitors: Binding region mobilities of intact and reactive-site hydrolyzed Cucurbita maxima trypsin inhibitor (CMTI)-III of the squash family and comparison with those of counterparts of CMTI-V of the potato I family.

Serine proteinase protein inhibitors follow the standard mechanism of inhibition (Laskowski M Jr, Kato I, 1980, Annu Rev Biochem 49:593-626), whereby an enzyme-catalyzed equilibrium between intact (I) and reactive-site hydrolyzed inhibitor (I*) is reached. The hydrolysis constant, Khyd, is defined as [I*]/[I]. Here, we explore the role of internal dynamics in the resynthesis of the scissile bond by comparing the internal mobility data of intact and cleaved inhibitors belonging to two different families. The inhibitors studied are recombinant Cucurbita maxima trypsin inhibitor III (rCMTI-III; Mr 3 kDa) of the squash family and rCMTI-V (Mr approximately 7 kDa) of the potato I family. These two inhibitors have different binding loop-scaffold interactions and different Khyd values--2.4 (CMTI-III) and 9 (CMTI-V)--at 25 degrees C. The reactive-site peptide bond (P1-P1') is that between Arg5 and Ile6 in CMTI-III, and that between Lys44 and Asp45 in CMTI-V. The order parameters (S2) of backbone NHs of uniformly 15N-labeled rCMTI-III and rCMTI-III* were determined from measurements of 15N spin-lattice and spin-spin relaxation rates, and [1H]-15N steady-state heteronuclear Overhauser effects, using the model-free formalism, and compared with the data reported previously for rCMTI-V and rCMTI-V*. The backbones of rCMTI-III [(S2) = 0.71] and rCMTI-III* [(S2) = 0.63] are more flexible than those of rCMTI-V [(S2) = 0.83] and rCMTI-V* [(S2) = 0.85]. The binding loop residues, P4-P1, in the two proteins show the following average order parameters: 0.57 (rCMTI-III) and 0.44 (rCMTI-III*); 0.70 (rCMTI-V) and 0.40 (rCMTI-V*). The P1'-P4' residues, on the other hand, are associated with (S2) values of 0.56 (rCMTI-III) and 0.47 (rCMTI-III*); and 0.73 (rCMTI-V) and 0.83 (rCMTI-V*). The newly formed C-terminal (Pn residues) gains a smaller magnitude of flexibility in rCMTI-III* due to the Cys3-Cys20 crosslink. In contrast, the newly formed N-terminal (Pn' residues) becomes more flexible only in rCMTI-III*, most likely due to lack of an interaction between the P1' residue and the scaffold in rCMTI-III. Thus, diminished flexibility gain of the Pn residues and, surprisingly, increased flexibility of the Pn' residues seem to facilitate the resynthesis of the P1-P1' bond, leading to a lower Khyd value.

Amino Acid Sequence↗

PubMed1998

Effect of Gibberellin Biosynthesis Inhibitors on Native Gibberellin Content, Growth and Floral Initiation in Sorghum bicolor.

CCC, uniconazol, ancymidol, prohexadione-calcium (BX-112), and CGA 163'935, which represent three groups of gibberellin (GA) biosynthesis inhibitors, were applied as a soil drench to Sorghum bicolor cultivars 58M (phyB-1, phytochrome B-deficient mutant) and 90M (phyB-2, equivalent phenotypically to wild type, PHYB, except for small differences in flowering dates). The inhibitors that block steps before GA12 (CCC, uniconazol, and ancymidol) lowered the concentrations of all endogenous early-C13alpha-hydroxylation pathway GAs found in sorghum: GA12, GA53, GA44, GA19, GA20, GA1, and GA8. In contrast, the inhibitors that block the conversion of GA20 --> GA1, (CGA 163'935 and BX-112) drastically reduced GA1 and GA8 levels, but they either did not change or caused accumulation of intermediates from GA12 to GA20. Combinations of pre-GA12 inhibitors and GA3 plus GA1 strongly reduced GAs other than GA1 and GA3. Each of these compounds inhibited shoot growth in both cultivars and delayed floral initiation in 90M. Floral initiation of 58M was also delayed by CCC, uniconazol, and ancymidol but not by CGA 163'935 and BX-112. This separation of shoot elongation from floral initiation in sorghum is novel. Both inhibition of shoot growth and delayed floral initiation were almost completely relieved by a mixture of GA3 and GA1 in both 58M and 90M. This observation, plus the much lower levels of endogenous GA3 than of GA1 observed in these experiments, implies that GA1 is the major endogenous GA active in shoot elongation. CGA 163'935 and BX-112 also failed to promote tillering in 58M, whereas inhibitors active before GA12 did so. The possibility that the GA20 --> GA1 inhibitors fail to block flowering and promote tillering in 58M because biosynthetic intermediates between GA12 and GA20 accumulate and/or because 58M is altered in GA metabolism in this same region of the biosynthetic pathway is discussed. Key Words. Gibberellin biosynthesis inhibitors-Phytochrome B-Flowering-Sorghum

Journal Article↗