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PubMed1989

Catechol stimulation of ferricyanide Hill reaction by spheroplasts of cyanobacterium, Synechococcus cedrorum: effect of temperature on catechol-stimulated oxygen evolution.

Catechol(o-dihydroxybenzene) at low concentrations (20-100 microM) stimulates FeCN-dependent O2 evolution of spheroplasts isolated from the cyanobacterium Synechococcus both in the presence and absence of DBMIB, an inhibitor of electron flow from PSII to PSI, the stimulation being two-fold with saturating concentration of (60 microM) catechol. Catechol thus appears to mediate the acceptance of electrons at the reducing side of PSII. Similarly it may act on the component of electron donor to PSII and caused the photoreduction of FeCN when O2 evolution capacity of spheroplasts is damaged by heat treatment. Analysis of the temperature effect on FeCN-supported O2 evolution by spheroplasts suggests that catechol shifts the temperature maxima to a lower temperature and thereby hastens the decay of O2 evolution capacity by heat as compared to the normal spheroplasts. Catechol also induces a change in the magnitude of activation energy for ferricyanide Hill activity of spheroplasts and lowers the transition temperature. These results suggest that lipophilic catechol brings about an alteration in membrane fluidity in cyanobacterial spheroplasts. Catechol is involved in a thermotropic destabilization of the membrane of the cyanobacterium. However, Al3+ was found to stabilize the membrane and raise the phase transition temperature. Further increase in temperature caused a gradual decline in the rate of O2 evolution.

Catechols↗
PubMed1989

Partial amino acid sequence of fructose-1,6-bisphosphatase from the blue-green algae Synechococcus leopoliensis.

Purified fructose-1,6-bisphosphatase from the cyanobacterium Synechococcus leopoliensis was S-carboxymethylated and cleaved with trypsin. The resulting peptides were purified by reversed-phase high performance liquid chromatography and the amino acid sequence of six of the purified peptides was determined by gas-phase microsequencing. The results revealed sequence homology with other fructose-1,6-bisphosphatases. The obtained sequence data provides information required for the design of oligonucleotide hybridization probes to screen existing libraries of cyanobacterial DNA. The determination of the amino acid sequence of cyanobacterial proteins may yield important information with respect to the endosymbiotic theory of evolution.

Amino Acid Sequence↗
PubMed1987

Preirradiation of medium induces a subsequent stimulation or inhibition of growth according to the physiological state in Synechococcus lividus in culture.

The proliferation of Synechococcus lividus cells grown in preirradiated medium was compared with the proliferation of cells grown in a shielded or freshly prepared medium. Aging of medium in a shielded chamber resulted in a slight inhibiting effect on growth in every phase of the cell cycle which was used. Preirradiation of medium resulted in a stimulation of growth observed on Day 7 in cultures inoculated with cells selected in the deceleration phase and an inhibition of growth in cultures inoculated with exponentially growing cells. Addition of catalase (100 U X ml-1) counteracted the stimulating effect but did not modify the inhibiting effect induced by preirradiated medium. Results demonstrated the indirect effect of low doses of irradiation, implying the presence of hydrogen peroxide in radiostimulation and other radioproducts in the inhibitory effect.

Catalase↗
PubMed1987

R-phycocyanin II, a new phycocyanin occurring in marine Synechococcus species. Identification of the terminal energy acceptor bilin in phycocyanins.

A new member of the phycocyanin family of phycobiliproteins, R-phycocyanin II (R-PC II) has been discovered in several strains of marine Synechococcus sp. R-PC II has absorption maxima at 533 and 554 nm, a subsidiary maximum at 615 nm, and a fluorescence emission maximum at 646 nm. It is the first phycoerythrobilin (PEB)-containing phycocyanin of cyanobacterial origin. The purified protein is made up of alpha and beta subunits in equal amounts and is in an (alpha beta)2 aggregation state. The alpha and beta subunits of this protein are homologous to the corresponding subunits of previously described C- and R-phycocyanins as assessed by amino-terminal sequence determination and analyses of sequences about sites of bilin attachment. R-PC II carries phycocyanobilin (PCB) at beta-84 and PEB at alpha-84 and beta-155 (residue numbering is that for C-phycocyanin), whereas in C-phycocyanin PCB is present at all three positions. In R-phycocyanin, the bilin distribution is alpha-84 (PCB), beta-84 (PCB), beta-155 (PEB). In both R-phycocyanin and R-phycocyanin II excitation at 550 nm, absorbed primarily by PEB groups, leads to emission at 625 nm from PCB. These comparative data support the conclusion that the invariant beta-84 PCB serves as the terminal energy acceptor in phycocyanins.

Amino Acid Sequence↗
PubMedDate not supplied

[Carbon dioxide fixation and its regulation in Synechococcus (Anacystis nidulans) cyanobacteria].

The bulk of 14CO2 assimilated in photosynthesis by the growing culture of Synechococcus was incorporated in the cell via the reductive pentose phosphate cycle. Up to 70% of the label was incorporated into phosphoglyceric acid and phosphoric esters of sugars at all stages of the active cultural growth after 1 min of exposition in the light in the presence of NaH14CO3. The relative proportion of the label in phosphorylated compounds of the reductive pentose phosphate cycle decreased if the exposition was increased to 20 min. The content of 14C in aspartic acid did not exceed 9%. In the presence of nucleotide peptide (NP) isolated from Anabaena variabilis, the overall rate of carbon dioxide assimilation rised by 50% as compared to the control by the fourth day of the growth. The specific rate of 14CO2 assimilation hardly changed within four days of the cultural growth; it was 44 nmole/min/mg, or 55 nmole/min/mg in the presence of NP. NP had no effect on the qualitative composition of the products of photosynthesis; however, the percentage of sugar phosphates, phosphoenolpyruvate and organic acids (carbohydrates at the stage of exponential growth) in these products increased in the presence of NP (exposition for 20 min). The percentage of carbohydrates was found to change only slightly as compared to the control in the presence of NP. The content of protein and RNA increased by 25-30% and the content of DNA by 60%. The action of NP was most pronounced if the content of DNA was calculated per cell. Therefore, there is a correlation between the content of DNA and the intensification of carbon dioxide fixation by the culture.

Bacterial Proteins↗
PubMed1983

Molecular architecture of a light-harvesting antenna. Structure of the 18 S core-rod subassembly of the Synechococcus 6301 phycobilisome.

The 18 S subassembly particles obtained by partial dissociation of phycobilisomes from Synechococcus 6301 (Anacystis nidulans) strain AN 112 contain approximately one-half of the mass of the phycobilisome and include core-rod junctions (Yamanaka, G., Lundell, D. J., and Glazer, A. N. (1982) J. Biol. Chem. 257, 4077-4086). The polypeptide composition of 18 S complexes, determined by analysis of uniformly 14C-labeled phycobilisomes, gave the following stoichiometry: 75K:27K:18.3K:alpha beta allophycocyanin monomer: alpha beta phycocyanin monomer of 1:2:1:5:6; where 75K, 27K, etc. represent polypeptides of 75, 27 kilodaltons, etc. The 18.3K polypeptide is a hitherto underscribed biliprotein bearing a single phycocyanobilin. The NH2-terminal sequence of this subunit was determined to be homologous to that of the beta subunit of allophycocyanin. Chromatography of products resulting from limited trypsin treatment of the 18 S complex led to the isolation of three subcomplexes: a mixture of (alpha beta)3 . 22K and (alpha beta)3 . 24K phycocyanin complexes, an (alpha beta)3 allophycocyanin trimer, and an (alpha beta)2 . 18.3K.40K.11K allophycocyanin-containing complex. The 22K and 24K components were products of the degradation of the 27K polypeptides, whereas the 40K and 11K components were derived from the 75K polypeptide. The subcomplexes accounted for the composition of the 18 S complex. Determination of the composition, stoichiometry, and spectroscopic properties of the subcomplexes has led to a model of the polypeptide arrangement within the 18 S complex and of the pathway of energy transfer among these polypeptides.

Amino Acid Sequence↗
PubMed1983

Molecular architecture of a light-harvesting antenna. Quaternary interactions in the Synechococcus 6301 phycobilisome core as revealed by partial tryptic digestion and circular dichroism studies.

The core of the phycobilisomes of Synechococcus 6301 (Anacystis nidulans) strain AN112 consists of two cylindrical elements each made up of the same four distinct subcomplexes: A (alpha AP beta AP)3; B (alpha AP beta AP)2 . 18.3K . 75K; C (alpha 1APB alpha 2AP beta 3AP) . 10.5K; and D (alpha AP beta AP)3 . 10.5K, where alpha AP and beta AP are the subunits of allophycocyanin, alpha APB is the subunit of allophycocyanin B, and 18.3K, 75K, and 10.5K are polypeptides of 18,300, 75,000, and 10,500 Da, respectively. An 18 S subassembly containing subcomplexes A and B has previously been characterized (Yamanaka, G., Lundell, D. J., and Glazer, A. N. (1982) J. Biol. Chem. 257, 4077-4086; Lundell, D. J., and Glazer, A. N. (1983) J. Biol. Chem. 258, 894-901, 902-908). A ternary core subassembly, containing complexes A, B, and C, was isolated from a limited tryptic digest of AN112 phycobilisomes and characterized with respect to composition and spectroscopic properties. Isolation of this ternary subassembly also establishes that subcomplex D must occupy a terminal position in each of the two core cylinders. Spectroscopic studies of the individual complexes, A-D, of the subassemblies AB and ABC, and of intact AN112 phycobilisomes showed core assembly-dependent changes in the circular dichroism spectra indicative of changes in the environment and/or conformation of the bilin chromophores within the individual subcomplexes. Two terminal energy acceptors are present in the phycobilisome core, alpha APB and 75K. No indication of interaction between the chromophores on these polypeptides was detected by circular dichroism spectroscopy. This result indicates that the bilins on alpha APB and 75K act as independent energy acceptors rather than as exciton pairs.

Circular Dichroism↗
PubMed1981

Molecular architecture of a light-harvesting antenna. In vitro assembly of the rod substructures of Synechococcus 6301 phycobilisomes.

The 75-, 33-, 30-, and 27-kilodalton polypeptide components ("linker polypeptides") of the phycobilisome of the unicellular cyanobacterium Synechococcus 6301 have been purified and characterized. In 0.6 M NaK phosphate buffer at pH 8, the 33-, 30-, and 27-kilodalton polypeptides assemble phycocyanin into ordered aggregates, whereas the 75-kilodalton polypeptide does not interact with phycocyanin. In the presence of the 33- and 30-kilodalton polypeptides, phycocyanin is assembled into hexameric discs and rods of stacked discs with the ultrastructural characteristics of the rod elements of intact phycobilisomes. Interaction of phycocyanin with only the 27-kilodalton polypeptide leads solely to the formation of discs that do not assemble into rods. Rods formed by interaction of phycocyanin with the 30- and 33-kilodalton polypeptides in the presence of the 27-kilodalton polypeptide are much shorter than those formed in its absence. This suggests that addition to growing rods of discs formed from phycocyanin and the 27-kilodalton polypeptide terminates rod assembly. Ordered structures formed upon interaction of phycocyanin with individual linker polypeptides contain at least 1 eq of linker polypeptide/(alpha beta)6 hexamer of phycocyanin. Complexes of phycocyanin with different linker polypeptides have distinctive spectroscopic properties that suggest a polar energy transfer along rod substructures toward the core. The linker polypeptides show no absorbance in the visible region of the spectrum. Peptide mapping shows that they are not related to each other by proteolytic processing.

Amino Acids↗
PubMed1981

Allophycocyanin B. A common beta subunit in Synechococcus allophycocyanin B (lambda max 670 nm) and allophycocyanin (lambda max 650 nM).

In cyanobacterial phycobilisomes, light energy absorbed by phycocyanin (lambda max 620 nm) is transferred to allophycocyanin (AP; lambda max 650 nm) and allophycocyanin B (AP-B; lambda max 670 nm) and emitted primarily at 680 nm. This emission maximum coincides with that of pure AP-B. Previous studies have shown that Synechococcus 6301 AP and AP-B are both (alpha beta)3 trimers with a number of similar properties. Here, we show that the beta subunits of AP and AP-B have identical molecular weights, isoelectric points, absorption spectra, NH2-terminal sequences, yield almost indistinguishable tryptic peptide maps, and can substitute for each other in hybridization with the alpha subunits. We conclude that the beta subunits are identical polypeptides. By the same criteria, the alpha subunits of these two proteins are clearly unique polypeptides. The alpha subunits carry the information which determines the absorption and fluorescence emission spectra of the proteins, e.g. the hybrid of the alpha subunits of AP-B with the beta subunits of AP has a lambda max of 670 nm and an emission maximum of 680 nm. In mixtures of AP-B and AP, heterologous trimers are formed in a near-statistical manner by subunit exchange. In such trimers, AP-B alpha beta monomers act as terminal energy acceptors.

Amino Acid Sequence↗
PubMed1994

A light-repressed transcript found in Synechococcus PCC 7002 is similar to a chloroplast-specific small subunit ribosomal protein and to a transcription modulator protein associated with sigma 54.

The gene encoding a novel light-repressed transcript (lrtA) contained within a 2.7-kbp EcoRI fragment has been cloned and sequenced from the unicellular cyanobacterium, Synechococcus PCC 7002. Northern analysis indicates that this transcript is synthesized rapidly in the dark, but upon 20 min of illumination, transcript levels fall below detectable limits. An open reading frame was located 378 bases from the start of the transcript which encodes a 21-kDa protein with significant homology to two hitherto different proteins. The protein sequence LrtA showed 37% sequence identity and 58% sequence similarity to the chloroplast-specific small subunit ribosomal protein, S30, and 37% sequence identity and 60% sequence identity and 60% sequence similarity to the reported transcription modulator protein of sigma 54 found in Klebsiella pneumonia and Azotobacter vinelandii. Expression of the lrtA gene product is not detectable within 1 h after placing the cells in the dark, however, within 2.5 min of illumination, [35S]methionine incorporated into a 21-kDa protein. To a lessor extent, [35S]methionine incorporation into a 17- and a 14-kDa protein was also seen which was followed by two other recognizable waves of translation at 5 and 10 min. This incorporation was not blocked by rifampicin added to dark-adapted cells prior to illumination. [35S]Methionine pulsed-labeling experiments suggested that the translation of lrtA occurred only during the first 10 min of reillumination of dark-adapted cells. The loss of initial [35S]methionine labeling in the light of the 21-kDa protein in a kanamycin-interrupted lrtA gene mutant suggests that the lrtA codes for the 21-kDa protein.

Amino Acid Sequence↗
PubMed1993

The X-ray structure of Synechococcus ribulose-bisphosphate carboxylase/oxygenase-activated quaternary complex at 2.2-A resolution.

The structure of the hexadecameric ribulose-bisphosphate carboxylase/oxygenase from Synechococcus PCC6301 has been solved to 2.2-A resolution. Crystallization was in the presence of CO2, Mg2+, and 2'-carboxyarabinitol bisphosphate to form a stable enzyme quaternary complex that mimics one of the intermediate states of the carboxylation reaction. The structure was solved by molecular replacement using the coordinates of spinach carboxylase. The deviations in C alpha positions of the L- and S-subunits are only 0.3 and 2.0 A, respectively, and localized at specific regions of the two polypeptides. One region that shows significant divergence of the peptide backbone is loop 6 of the beta barrel in the L-subunit. Two other elements, the C terminus, and a highly conserved loop of the N-terminal domain of a second L-subunit, interact with loop 6 in the quaternary complex. These three regions, plus two other flexible segments, completely enfold the bisphosphate inhibitor. Significant alteration in their spatial relationship must occur to allow substrates or products access to and from the active site. The active site residues, activating cofactors, and inhibitor are well resolved in the electron density map. The disposition of these groups around the essential metal provides some indication of their role at different stages of the catalytic cycle.

Amino Acid Sequence↗
PubMed1993

Adaptive response of wild and mutant type Synechococcus cedrorum to a polychlorinated pesticide-endosulfan.

The effect of endosulfan, a hexachlorinated pesticide, on growth, inorganic nitrogenous nutrient uptake (NO3-, NO2- and NH4+), change in pigmentation and glycogen content on wild type and chemically mutagenised cells of Synechococcus cedrorum was investigated. The pattern of response to pesticide stress in wild and mutant type was the same. Growth reappeared in both after a period of initial lag in presence of endosulfan. The duration of lag increased with increasing doses of pesticide. Paradoxically, however, the rate of uptake of NO3-, NO2- and NH4+, pigment and glycogen content progressively increased with increasing doses. The difference in the adaptation response between wild and mutant types was observed only in the concentration of pesticide that could be tolerated; with the mutant tolerating 2.5 fold more.

Adaptation, Physiological↗
PubMed1993

Thioic O-acid ester in sulfolipid isolated from freshwater picoplankton cyanobacterium, Synechococcus sp.

A thioic O-acid ester-containing sulfolipid (thionsulfolipid) was isolated from cells of picoplankton cyanobacterium, Synechococcus sp. The lipid accounted for about 0.2% of the lyophilized cells. The lipid was subjected to mild alkaline hydrolysis, and the structures of the hydrolysis products were identified by infrared spectra, mass and nuclear magnetic resonance spectrometries, as fatty acids and hexadecane-, hexadecene- and tetradecanethioic S-acids. Thioic S-acid was further confirmed by the synthesis of hexadecanethioic S-acid from palmitoylchloride and hydrogen sulfide. The positional distribution of the thioic acid ester in the lipid was determined by beta-galactosidase, sulphur-oxygen exchange reaction using silver nitrate, and lipase hydrolysis of the diacylglycerol derived from the lipid. The structure of the thionsulfolipid was identified as 6-sulfo-alpha-D-quinovopyranosyl(1-->1')-2'-O-acyl-3'-O-thioacy l -2-glycerol. When cells of HL 60, as a human lymphoma, were cultured with thionsulfolipid, 61% of the cell growth was inhibited at the concentration of 200 micrograms/ml. The lipid was toxic against minnows (Tanichtys albonubes). The LD50 was 20 ppm. Thioic O-acid ester-containing lipid (thionsulfolipid) has not been found in any other photosynthetic organisms.

Cyanobacteria↗
PubMed1993

Rod structure of a phycoerythrin II-containing phycobilisome. I. Organization and sequence of the gene cluster encoding the major phycobiliprotein rod components in the genome of marine Synechococcus sp. WH8020.

Phycobilisomes of the unicellular marine cyanobacteria are unique in having rod substructures with two distinct phycoerythrins, PE I and PE II, with five and six bilins, respectively (Ong, L. J., and Glazer, A. N. (1991) J. Biol. Chem. 266, 9515-9527). The genes for the alpha and beta subunits of PE I, PE II, and phycocyanin, and that for the PE II-associated linker polypeptide, are clustered on a single 15-kilobase region of the genome of Synechococcus sp. WH8020. Complete sequencing of this region allowed definitive assignment of the positions of all bilin attachment sites in these phycobiliproteins. Twelve other open reading frames are closely associated with the structural genes specified above. Six are homologous to open reading frames adjacent to phycobiliprotein genes in other cyanobacteria and inferred to be involved in bilin addition. This is the largest number of open reading frames of this class known in any cyanobacterium. Another of the open reading frames has a short region of striking similarity to the active site sequence of a bovine protein-phosphotyrosine phosphatase.

Amino Acid Sequence↗
PubMed1995

Purification and characterization of phosphoribulokinase from the cyanobacterium Synechococcus PCC7942.

Phosphoribulokinase (PRK) was purified to electrophoretic homogeneity from Synechococcus PCC7942 with high specific activity. Molecular masses of the native enzyme and its subunit were 178 and 42 kDa, respectively. Cys-17 and Cys-38 were conserved in the cyanobacterial PRK, but 18 amino acid residues between them were missing among the 40 residues found in higher plant PRKs.

Amino Acid Sequence↗
PubMed1997

Stabilization by glycinebetaine of photosynthetic oxygen evolution by thylakoid membranes from Synechococcus PCC7002.

Active thylakoid membranes were prepared from Synechococcus PCC7002 in a medium that contained glycinebetaine. The oxygen-evolving activity of photosystem II of these thylakoid membranes was enhanced and stabilized by the presence of glycinebetaine. The heat stability of the oxygen-evolving activity of the thylakoid membranes was also enhanced by glycinebetaine.

Betaine↗
PubMed2004

Chlorosis during nitrogen starvation is altered by carbon dioxide and temperature status and is mediated by the ClpP1 protease in Synechococcus elongatus.

The interactive effects of inorganic carbon status, temperature and light on chlorosis induced by nitrogen deficiency, and the roles of Clp proteases in this process were investigated. In wild-type cultures grown in high or ambient CO(2), following transfer to media lacking combined nitrogen, phycocyanin per cell dropped primarily through dilution of the pigment through cell division, and also suffered variable degrees of net degradation. When grown at high CO(2) (5%), chlorophyll (Chl) suffered net degradation to a greater extent than phycocyanin. In marked contrast, growth at ambient CO(2) resulted in Chl per cell dropping through dilution. Conditions that drove net Chl degradation in the wild-type resulted in little or no net Chl degradation in a clpPI inactivation mutant, with Chl content dropping largely through growth dilution in the mutant. The chlorotic response of a clpPII inactivation strain was nearly the same as that of wild-type, although phycocyanin degradation may have been slightly accelerated in the former.

Bacterial Proteins↗