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T Date

Publications and source records attributed to T Date.

At least 109 records · Page 6Linked to original sources
PubMed1983

Demonstration by a novel genetic technique that leader peptidase is an essential enzyme of Escherichia coli.

It was previously shown that two separate regions of DNA are required for expression of the cloned leader peptidase gene on plasmid pTD101 (T. Date and W. Wickner, Proc. Natl. Acad. Sci. U.S.A. 78:6106-6110, 1981). Both loci have been mapped in detail, and their roles have been established. A 1.3-kilobase region, termed the L region, encodes the 37,000-dalton leader peptidase protein. Another region, termed the P region, is about 1.5 kilobases away from the L region and is less than 350 base pairs long. The P region acts in cis to the L region, suggesting that it plays a role as a promoter. A technique for inactivation of the leader peptidase gene on the Escherichia coli chromosome has been developed to examine whether the leader peptidase which we had cloned is essential for cell growth. A specific plasmid (P(-) L(-)) which deletes both the P region and a substantial portion of the L region was constructed and transformed into a polA mutant strain. The plasmid cannot replicate in this strain; thus, the plasmid-borne ampicillin resistance is lost unless the plasmid DNA recombines into the chromosome. Integration of the P(-) L(-) plasmid did not yield any viable ampicillin-resistant cells, whereas the three control plasmids, P(+) L(+), P(+) L(-), and P(-) L(+), did. When the P(-) L(-) plasmid was transformed into the polA(Ts) strain, the strain could only grow in the presence of ampicillin at a permissive temperature, suggesting that integration of the plasmid into the host chromosome leads to inactivation of the chromosomal leader peptidase gene. Southern hybridization analysis demonstrated that the integration of plasmids into the chromosome occurred at the homologous site. This study demonstrates that expression of the leader peptidase gene is critical for cell growth.

Chromosome Mapping↗
PubMed1983

Study of atrial contraction in sick sinus syndrome using conventional and esophageal echocardiography.

To evaluate the active systolic function of both atria in sick sinus syndrome (SSS), conventional and esophageal echocardiograms were recorded in 22 normal subjects (Normal), 5 patients (pts) with sinus bradycardia (Group I), 9 with sinoatrial block or sinus arrest (Group II), 10 with bradycardia-tachycardia syndrome (BTS, Group III) and 6 with transient atrial fibrillation (Group IV). Two pts in Group II and 8 in Group III had a history of syncope. Atrial filling fraction obtained by the left ventricular echogram (AFF by LV echo) and posterior wall excursion of the aorta during atrial contraction (Ea) were determined by the conventional echocardiogram. The excursion of the interatrial septum during atrial contraction (Eb) and the dimensional shortening of the right atrium during atrial contraction (Ec) were determined by the esophageal echocardiogram. Results were as follows: AFF was almost the same in Normal, and Group I, II and IV, but it was significantly lower in Group III. AFF was also decreased in 2 pts in Group II who had a history of syncope. Both Ea and Eb in Group III were significantly lower than those in the other groups. Ec was not significantly different among all groups, although one patient in Group III had markedly decreased Ec. There was a significant correlation between Ea and AFF (r = 0.638, p less than 0.001). We conclude that in a number of cases with SSS, especially BTS, left atrial active contraction is significantly impaired in addition to the electrophysiological abnormality.

Adult↗
PubMed1982

Anomalies of nanosecond ultrasonic relaxation in the lipid bilayer transition.

The frequency dependence of ultrasonic velocity as well as absorption in a suspension of sonicated dipalmitoylphosphatidylcholine vesicles was measured by a differential ultrasonic resonator. The frequency was scanned between 1.3 and 13 MHz and the temperature was varied from 25 to 47 degrees C. A pronounced relaxation was observed in the time range of 10 ns. The data were analyzed assuming a single relaxation which appeared to be a good approximation. The relaxation time as well as relaxation strength increased anomalously in the vicinity of the gel-to-liquid crystal transition of 41.5 degrees C. This result represents the first definite evidence of the critical slowing down in the lipid bilayer and is discussed in terms of the Landau theory of phase transition. The possible biological significance of the mechanical relaxation is also presented.

Kinetics↗
PubMed1982

[A situational psychological look at epileptic seizures].

Seven cases who developed paroxysm during adolescence and/or in a special situation were selected and subjected for studies of the existing pattern of the patients and also of the paroxysmal situation in relation to their individual life history. (1) "Schlafepilepsie" and psychomotor seizure were identified as being the pattern of epilepsy that developed exceedingly in a situational dependent fashion. (2) An intensive linkage between the patients and their parents was observed. (3) A forced separation from their parents allows to radicalize their conflicts. (4) Their existence is compounded further by the situation where their intrinsic order is compelled to change, and control of themselves becomes difficult to maintain. (5) This process permits the revelation of a latent process of epilepsy.

Adolescent↗
PubMed1981

Leader peptidase is found in both the inner and outer membranes of Escherichia coli.

Many membrane proteins are synthesized as transient precursors with an NH2-terminal leader (or signal) peptide. During insertion of these proteins into the membrane, leader peptides are removed by leader peptidase. One such enzyme has been detected in detergent extracts of Escherichia coli membranes and extensively purified using as an assay the removal of the leader sequence of procoat, the precursor of the major coat protein of bacteriophage M13. We now report that this leader peptidase is found in equal abundance in the inner and outer membranes of E. coli. Enzyme from each membrane accurately cleaves procoat to mature M13 coat protein. The salt, pH, and Mg2+ optima and inhibitor sensitivities of enzyme from each membrane are identical. Furthermore, the activities are indistinguishable upon ion exchange chromatography and nondenaturing gel electrophoresis. Finally, a strain of E. coli with a plasmid which causes overproduction of leader peptidase has elevated levels of enzyme in both the inner and outer membranes. Leader peptidase is the only known enzyme which is found in both inner and outer membrane fractions of E. coli; this may reflect its role in membrane biogenesis.

Cell Membrane↗
PubMed1981

Isolation of the Escherichia coli leader peptidase gene and effects of leader peptidase overproduction in vivo.

The only covalent modifications known to accompany protein insertion into membranes or protein secretion are glycosylation and the proteolytic removal of an NH2-terminal leader (signal) sequence. This latter reaction is catalyzed by leader peptidase, a constitutive, membrane-bound proteinase. We now report the identification of a plasmid-bearing strain of Escherichia coli that overproduces leader peptidase 4- to 6-fold. This strain grows normally and shows an unaltered polypeptide composition of inner ad outer membranes. The leader peptidase gene has been subcloned and transferred from this plasmid to the multicopy plasmid pBR322, yielding a new plasmid (pTD101). Strains transformed by pTD101 have a 30-fold increase in leader peptidase. We have studied the effect of leader peptidase overproduction on the insertion of newlymade M13 phage coat protein into the plasma membrane of infected cells. The overproducer strain, when infected by M13 phage, shows a dramatic acceleration in the conversion of procoat (a cytoplasmic precursor form) to coat (an integral, transmembrane protein). Thus the leader peptidase that converts M13 procoat to coat in vitro can catalyze this reaction in vivo as well.

Coliphages↗
PubMed1980

Mechanisms of membrane assembly: effects of energy poisons on the conversion of soluble M13 coliphage procoat to membrane-bound coat protein.

The coat protein (gene 8 product) of coliphage M13 spans the host cell plasma membrane prior to its assembly into extruding virions. It is made as a soluble precursor, termed procoat, with an extra 23 NH2-terminal amino acid residues. We have examined the effect of metabolic poisons on the assembly of procoat into the plasma membrane and its proteolytic conversion to coat protein. Protein synthesis and proline uptake were measured to assess the effect of each poison on cellular high-energy phosphate and on the transmembrane protonmotive force, respectively. Arsenate, which abolished protein synthesis but did not affect proline uptake, had no measurable effect on the conversion of procoat to coat protein. In contrast, the uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP) blocked conversion of procoat to coat protein. Neither CCCP nor arsenate inhibited the ability of a detergent-solubilized and highly purified preparation of leader peptidase to convert procoat to coat protein in the presence of detergents. The procoat that accumulated in the presence of CCCP was membrane bound. A spontaneous mutant that grows in the presence of CCCP showed (i) CCCP-resistant proline uptake in whole cells, (ii) CCCP-resistant uptake in inner membrane vesicles, and (iii) CCCP-resistant conversion of procoat protein to coat protein. These data suggest that an electrochemical gradient is at least indirectly necessary for the proper assembly of procoat into the cellular membrane.

Arsenates↗
PubMed1980

Procoat, the precursor of M13 coat protein, requires an electrochemical potential for membrane insertion.

The coat protein of coliphage M13 spans the host cell cytoplasmic membrane prior to its assembly into extruding virus. It is made as a soluble cytoplasmic precursor, termed "procoat," with 23 extra amino acid residues at the NH2 terminus. Procoat binds to the cell membrane and is converted proteolytically to coat protein. When the electrochemical gradient of an infected cell is rapidly dissipated by uncouplers, procoat still binds to the plasma membrane but is not converted to coat. We report here that membrane-bound procoat is only detected at the inner face of the cytoplasmic membrane and that uncouplers prevent it from integrating into a transmembrane conformation.

Coliphages↗
PubMed1980

[Reflections on epileptic personality changes].

When epileptic seizures occur suddenly in puberty, the patient is seized with the feeling of anxiety, isolation and despair, and this feeling is increased by the special quality of puberty. The patient tries to overcome this critical situation by including "epilepsy" in his own personality. When this process is accomplished in puberty in which an ego-identification is done, an epileptic personality disorder is formed gradually. Accordingly, how the patient tides over this crisis is important for the formation of an epileptic personality disorder. In order to prevent the development of this condition, it is necessary to apply psychotherapy.

Epilepsy↗
PubMed1979

Kinetic studies of the interaction between MS2 phage and F pilus of Escherichia coli.

The kinetics of the binding reaction of MS2 phage to free F pili, which were highly purified from Escherichia coli, has been studied using a membrane filter assay. The rate of dissociation (kd) of the MS2-phage--F-pilus complex is very slow and follows first-order kinetics with a half-life of 4.2 h at 30 degrees C in the standard buffer. The dissociation rate is rather insensitive to temperature, but becomes more rapid at high ionic strength or at basic pH. In a 0.25 M ionic strength buffer, the half-life of the complex is about 1.0 min. The rate of association is very fast and follows second-order kinetics with the rate constant for association (ka) being 8 x 10(7) M-1 s-1 at 30 degrees C in the standard buffer. The rate of association is almost insensitive to ionic strength but slightly sensitive to pH or temperature. Monovalent cations can also promote the binding reaction as well as divalent cations but the complex formed with monovalent cation is unstable. A study of the kinetics of dissociation suggests that there are two types of interaction between MS2 phage and F pilus; one is a strong interaction formed with divalent cations and the other is a weak one formed with monovalent cations. The physical nature of the bonds involved in the former and the latter seems to be mainly electrostatic and non-electrostatic respectively. The mechanism of the binding reaction is discussed.

Coliphages↗
PubMed1977

Freezing index in cryosurgery on the prostate gland.

Cryosurgery has been performed on 18 patients with prostatic hypertrophy, and the following conclusions are reached: The quotient obtained by dividing the estimated weight of the prostate gland by the frozen weight obtained by an equation is called the freezing index, and this index can be introduced into the evaluation of the results of cryosurgery on the prostate gland. Cryosurgery was not markedly effective in cases of freezing indices over 0.76, and the incidence of complications was high in cases of freezing indices not more than 0.5. The ideal freezing index obtained empirically was 0.6. No dysuria has recurred during past three years in the cases where cryosurgery was assessed satisfactory in effect within two to three months.

Aged↗