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Biomedical subjects

Y Kamio

Publications and source records attributed to Y Kamio.

At least 163 records · Page 9Linked to original sources
PubMed1988

Purification of Rts1 RepA protein and binding of the protein to mini-Rts1 DNA.

RepA protein, essential for the replication of plasmid Rts1, was purified, and its binding to mini-Rts1 subregions was examined by a DNase I protection assay. RepA protected the incI and incII iterons, a region immediately upstream of the repA promoter, and a 10-base-pair region located between the most external incII iteron and a GATC box. The protection was less efficient when preheated RepA was used.

Bacterial Proteins↗
PubMed1987

Structural specificity of diamines covalently linked to peptidoglycan for cell growth of Veillonella alcalescens and Selenomonas ruminantium.

Putrescine and cadaverine are essential constituents of the peptidoglycan of Veillonella alcalescens, Veillonella parvula, and Selenomonas ruminantium and are necessary for the growth of these organisms (Y. Kamio and K. Nakamura, J. Bacteriol. 169:2881-2884, 1987, and Y. Kamio, H. Pösö, Y. Terawaki, and L. Paulin, J. Biol. Chem. 261:6585-6589, 1986). In this study, the structural specificity of the diamine requirement for normal cell growth of these bacteria was examined by using a series of diamines with a general structure of NH3+ X (CH2)n X NH3+. Diaminohexane (n = 6) which was incorporated into the peptidoglycan was as effective as putrescine (n = 4) and cadaverine (n = 5) for normal cell growth. However, diaminopropane (n = 3) and diaminoheptane (n = 7) were less effective for growth than diaminohexane, although they were incorporated into the peptidoglycan to the same extent.

Autoradiography↗
PubMed1987

Essential DNA sequence for the replication of Rts1.

The promoter sequence of the mini-Rts1 repA gene encoding the 33,000-dalton RepA protein that is essential for replication was defined by RNA polymerase protection experiments and by analyzing RepA protein synthesized in maxicells harboring mini-Rts1 derivatives deleted upstream of or within the presumptive promoter region. The -10 region of the promoter which shows homology to the incII repeat sequences overlaps two inverted repeats. One of the repeats forms a pair with a sequence in the -35 region, and the other forms a pair with the translation initiation region. The replication origin region, ori(Rts1), which was determined by supplying RepA protein in trans, was localized within 188 base pairs in a region containing three incII repeats and four GATC sequences. Dyad dnaA boxes that exist upstream from the GATC sequences appeared to be dispensable for the origin function, but deletion of both dnaA boxes from ori(Rts1) resulted in reduced replication frequency, suggesting that host-encoded DnaA protein is involved in the replication of Rts1 as a stimulatory element. Combination of the minimal repA and ori(Rts1) segments, even in the reverse orientation compared with the natural sequence, resulted in reconstitution of an autonomously replicating molecule.

Bacterial Proteins↗
PubMed1987

Putrescine and cadaverine are constituents of peptidoglycan in Veillonella alcalescens and Veillonella parvula.

Veillonella alcalescens ATCC 17745, a strictly anaerobic, gram-negative small coccus, requires putrescine or cadaverine for growth (M. B. Ritchey, and E. A. Delwiche, J. Bacteriol. 124:1213-1219, 1975). Both putrescine and cadaverine were demonstrated to be incorporated exclusively into the peptidoglycan layer of V. alcalescens ATCC 17745. V. parvula GAI 0574 also proved to contain putrescine as a component of peptidoglycan. The primary chemical structure of the peptidoglycan common to the two Veillonella species is N-acetylglucosamine-N-acetylmuramic acid-L-alanine-D-glutamic acid gamma-meso-diaminopimelic acid-D-alanine. Putrescine or cadaverine links covalently to the alpha-carboxyl group of the D-glutamic acid residue of the peptidoglycan is necessary for normal cell growth. In V. alcalescens ATCC 17745, above 40% saturation at cadaverine linked to the alpha-carboxyl group of the D-glutamic acid residue of the peptidoglycan is necessary for normal growth.

Cadaverine↗
PubMed1986

Cadaverine covalently linked to a peptidoglycan is an essential constituent of the peptidoglycan necessary for the normal growth in Selenomonas ruminantium.

Cadaverine links covalently to the D-glutamic acid residue of the peptidoglycan in Selenomonas ruminantium, a strictly anaerobic Gram-negative bacterium (Kamio, Y., Itoh, Y., and Terawaki, Y. (1981) J. Bacteriol. 146, 49-53). This report clarifies a physiological function of cadaverine in this organism by using DL-alpha-difluoromethyllysine, which had previously been shown to be a selective irreversible inhibitor of lysine decarboxylase of Mycoplasma dispar (Pösö, H., MaCann, P.P., Tanskanen, R., Bey, P., and Sjoerdsma, A. (1984) Biochem. Biophys. Res. Commun. 125, 205-210). DL-alpha-Difluoromethyllysine is now shown to be a potent and irreversible inhibitor of lysine decarboxylase of S. ruminantium in vitro; however, it did not inhibit the transfer of cadaverine to the alpha-carboxyl group of the D-glutamic acid residue of the peptidoglycan. DL-alpha-Difluoromethyllysine at 5 mM markedly inhibited the growth of the bacterium and caused rapid cell lysis. Immediately before the cell lysis, almost all cells became swollen, and such cells showed a loosened envelope structure when studied by electron microscopy. The peptidoglycan prepared from the DL-alpha-difluoromethyllysine-treated cells did not have covalently linked cadaverine. The growth inhibition by DL-alpha-difluoromethyllysine was completely reversed by adding cadaverine (1 mM) to the medium. Furthermore, the exogenous cadaverine was exclusively incorporated into the peptidoglycan in the presence of DL-alpha-difluoromethyllysine (5 mM), and a normal peptidoglycan was synthesized. The cell lysis and the formation of an abnormal cell structure were completely prevented by cadaverine added to the medium. We conclude that cadaverine covalently linked to the peptidoglycan in S. ruminantium is an essential constituent of the peptidoglycan and is required for cell surface integrity and the normal growth of S. ruminantium.

Alanine↗
PubMed1985

Characterization of the ileS-lsp operon in Escherichia coli. Identification of an open reading frame upstream of the ileS gene and potential promoter(s) for the ileS-lsp operon.

The preceding paper presents evidence for the co-transcriptional expression of the ileS and lsp genes in Escherichia coli. To identify the promoter for the ileS-lsp operon, we have determined the nucleotide sequence of an 1.8-kilobase DNA fragment between the rpsT and IleS genes. The sequence data have revealed an open reading frame, designated gene X, which encodes a polypeptide with 312 amino acid residues. Both in vivo and in vitro expressions of the x gene result in the synthesis of a soluble protein with an apparent Mr of 35,000. The x gene is transcribed in the same direction as that of the ileS-lsp operon and opposite to that of the upstream adjacent rpsT gene. No transcription termination sequence can be discerned in the intercistronic region between the x and ileS genes. DNase I footprinting experiment revealed a RNA polymerase binding site at 170-151 base pairs upstream of the x gene.

Bacterial Proteins↗
PubMed1984

Complete nucleotide sequence of mini-Rts1 and its copy mutant.

The nucleotide sequence of the whole mini-Rts1 genome consisting of 1,855 base pairs was determined. In addition to the cluster of five 24-base-pair direct repeats previously detected (Y. Kamio and Y. Terawaki, J. Bacteriol. 155:1185-1191, 1983), another cluster of three 21-base-pair direct repeats was found. All eight repeats were located in one direction and contained a consensus sequence TTCCCCPyPyPuPuCACACACC. Between the two clusters, a large open reading frame that could encode a 32,980-dalton polypeptide consisting of 288 amino acids was assigned. The molecular size predicted from the amino acid composition was close to the value of a unique mini-Rts1 product, the RepA protein, newly determined in minicells. A copy mutant of mini-Rts1 obtained in vitro by hydroxylamine treatment contained two-base-pair substitutions, one of which was located in the RepA protein coding region, and the other was close to the region where the oriC homologous sequences exist.

Ampicillin↗
PubMed1983

Purification and properties of Selenomonas ruminantium lysine decarboxylase.

Selenomonas ruminantium, a strictly anaerobic, gram-negative bacterium isolated from sheep rumen, contains lysine decarboxylase (Y. Kamio et al., J. Bacteriol. 145:122-128, 1981). This report describes the synthesis, purification, and characterization of the enzyme. Lysine decarboxylase was synthesized in cells grown in chemically defined medium without lysine. The enzyme was purified approximately 1,800-fold to electrophoretic homogeneity. The native enzyme of approximate molecular weight 88,000 consisted of two identical subunits, each with a molecular weight of 44,000. Several properties of the enzyme were determined and compared with those of the lysine decarboxylases from Escherichia coli and Bacterium cadaverisis.

Amino Acids↗
PubMed1983

Nucleotide sequence of an incompatibility region of mini-Rts1 that contains five direct repeats.

The plasmid mini-Rts1, consisting of an EcoRI/HindIII fragment of about 1.8 kilobases (kb), contains an incompatibility determinant in its EcoRI/AccI region (0.5 kb). The nucleotide sequence of this incompatibility fragment was determined. A most striking feature of the sequence is the presence of five 24-base pair direct repeats. Four out of the five repeating units, which are contained in a 0.2-kb EcoRI/HincII fragment, were cloned en bloc in pACYC184 and found to express Rts1-specific incompatibility. In addition, the copy number of the mini-Rts1 plasmid appeared to be increased threefold upon removal of the 0.2-kb incompatibility region (incI) from the plasmid. This deletion derivative of mini-Rts1, as well as mini-Rts1, was maintained stably at 37 degrees C, but was cured at a high frequency at 42 degrees C. A possible role of the repeated nucleotide sequence was discussed. By subcloning the mini-Rts1 DNA, a second inc determinant (incII) was found on the AccI fragment, which is contiguous to the 0.5-kb EcoRI/AccI fragment.

Base Sequence↗
PubMed1983

[Evaluation of Hancock mitral valve by M-mode echocardiography. Clinical significance of the timing of closing and opening of the valve].

The valve function of a Hancock xenograft in the mitral position was evaluated by M-mode echocardiograms guided by the two-dimensional echocardiogram. From M-mode echocardiograms, the intervals from the second heart sound to mitral valve opening (II-MVo) and from the Q wave to mitral valve closure (Q-MVc) were measured in 24 patients with a Hancock xenograft, 16 with mitral stenosis (MS) and 20 normal controls. Twenty-four patients with a Hancock xenograft were divided into four groups according to the echocardiographic pattern of the xenograft. Fourteen with normal echocardiograms (I: N.P.), five with delayed opening of cusps from 20 to 90 msec (II: D.O.), three with a coarse fluttering of cusps in diastole (III: D.F.), and two with an obstructed prosthesis (IV: O.P.). The valve function of groups II and III was clinically normal. This suggests that a coarse fluttering of cusps and delayed opening of cusps do not always indicate malfunction of the Hancock xenograft. M-mode echocardiograms of group IV showed an increased thickening of cusps, multiple dense echoes between valve stents and a lack of a clear E point. The beat-to-beat variations of Q-MVc and II-MVo intervals showed no significant differences among patients with the Hancock xenograft, MS and normal controls. A small time-dependent variation of Q-MVc and II-MVo intervals observed in patients with the Hancock xenograft did not seem to interfere the reliable reproducibility of these intervals. In group I, II-MVo interval was 104 +/- 8 msec (mean +/- S.E.), which was significantly longer than that of normal controls (54.5 +/- 2.5 msec) (p less than 0.005). In groups II and III, II-MVo interval was almost equal to that of group I, but in two of group IV, this interval was 20 and 30 msec, respectively which was markedly shortened. Q-MVc intervals did not show significant differences among groups I, II, III and IV. There were significant differences in Q-MVc interval among patients with MS and the Hancock xenograft and normal controls. II-MVo interval of group I was inversely correlated with mean diastolic posterior wall velocity (MDPWV), stroke index (SI) and delta ejection time (ET), but significantly correlated with delta preejection period (PEP) and PEP/ET. However, there was no significant relationship between II-MVo interval and pulmonary capillary wedge pressure. This suggested that prolonged II-MVo interval reflects postoperative left ventricular dysfunction. In conclusion, to evaluate the function of a Hancock xenograft, echocardiograms of valve cusps and measurement of II-MVo interval have useful clinical significance.

Bioprosthesis↗
PubMed1982

Biosynthesis of cadaverine-containing peptidoglycan in Selenomonas ruminantium.

Cadaverine links covalently to the D-glutamic acid residue of the peptidoglycan in Selenomonas ruminantium, a strictly anaerobic, Gram-negative bacterium (Kamio, Y., Itoh, Y., and Terawaki, Y (1981) J. Bacteriol. 146, 49-53). This report describes the enzymatic properties of the particulate enzyme preparation in S. ruminantium which catalyzes the addition of cadaverine to the alpha-carboxyl group of D-glutamic acid residue of the peptidoglycan. Incorporation of cadaverine into the peptidoglycan required UDP-MurNAc-L-Ala-D-Glu-meso-2,5-diaminopimelic acid (DAP)-D-Ala-D-Ala (UDP-MurNAc-pentapeptide(DAP)), UDP-GlcNAc, and ATP. In addition, MgCl2 and cysteine stimulated the reaction. UDP-MurNAc-pentapeptide(DAP) could not be substituted for UDP-MurNAc-L-Ala-D-Glu-L-Lys-D-Ala-D-Ala as a precursor of cadaverine-containing peptidoglycan. GlcNAc-MurNAc-pentapeptide(DAP)-lipid (disaccharide-pentapeptide(DAP)-lipid) prepared enzymatically acted as an immediate acceptor of cadaverine in an ATP-dependent reaction in which the alpha-carboxyl group of D-glutamic acid is covalently linked to cadaverine. The [14C]cadaverine-containing disaccharide-pentapeptide(DAP)-lipid was isolated, and used for the synthesis of the peptidoglycan in the absence of cadaverine, ATP, UDP-MurNAc-pentapeptide(DAP), and UDP-GlCNAc. The peptidoglycan formed in vitro in the absence of penicillin G was not cross-linked.

Anti-Bacterial Agents↗