Shogo Nakamura

Toyama University, Тояма, Toyama, Japan

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Publications (8)16.67 Total impact

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    ABSTRACT: From the genome library of Staphylococcus warneri M, the two successive cell-lysis genes (holWMY and lytWMY) were cloned and characterized. The lytWMY gene encoded a protein (LysWMY), whose calculated molecular mass and pI were 54 kDa and 8.95, respectively. When overproduced in Escherichia coli, lysWMY directed a protein of 45 kDa (smaller than the predicted molecular mass), having N-terminal 13 residues identical with those predicted from DNA. Comparative analysis revealed that LysWMY significantly resembles the putative N-acetylmuramoyl-L-alanine amidases encoded by the staphylococcal phages phi11, 80 alpha, and Twort. Examination of modular organization of LysWMY identified three putative domains CHAP (for D-alanyl-glycyl endopeptidase), amidase (L-muramoyl-L-alanine amidase), and SH3 (cell wall recognition). Gene knockout analysis revealed that each of the two domains of CHAP and amidase was responsible for cell-lytic activity on a zymogram gel. Site-directed mutation of Cys29Ala, His92Ala, or Asn114Ala in the CHAP domain substantially reduced cell-lytic activity, suggesting that this Cys-His-Asn triad is crucial for the enzymatic function. On the other hand, the holWMY gene encoded a protein (HolWMY) with molecular mass and pI of 16 kDa and 4.36; this protein contained two potential transmembrane helices, resembling other predicted holins (a cytoplasmic membrane-disrupting protein) encoded by the S. aureus phage, phi11, 80 alpha, and Twort. Upon mitomycin C exposure of S. warneri M, a prophage (phiWMY) was induced and the virion was examined under electron microscopy. PCR amplification and sequencing revealed the presence of the holWMY-lysWMY genes in the phage genome.
    No preview · Article · Jun 2005 · Gene
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    ABSTRACT: Shotgun cloning of the Lactobacillus gasseri JCM 1131T whole DNA yielded two recombinant plasmids, p118gaY1 and p118gaY2, which directed cell lysis activity. Sequencing analysis revealed that the two plasmids carried almost identical inserted genes in following orders (truncated genes, in parentheses): in p118gaY1, (orf149)-orf92-holgaY-lysgaY-orf35-attL-(mnaAgaY1); in p118gaY2, (orfXgaY1)-orf169-orf149-orf92-holgaY-lysgaY-orf35-attP-(intgaY). The lysgaY-encoded protein (designated as LysgaY, 33.7 kDa) showed significant homology with putative muramidases (peptidoglycan-degrading enzyme) of the Lactobacillus phage phiadh, Lj965, Lj928, LL-H, mv4, and mv1. By zymogram analysis, LysgaY overproduced in Escherichia coli exhibited lytic activity towards 17 Gram-positive bacterial strains, including lactobacilli, lactococci, and staphylococci. The holgaY-encoded protein (15.7 kDa) contained three potential transmembrane helices, resembling putative holins (cytoplasmic membrane-disrupting protein) of Lj928 and Lj965. On the other hand, another clone p118gaYR obtained by EcoRI-shotgun cloning carried the (ptsCgaY1)-attR-(intgaY) genes. Three sequences, attL, attP, and attR, had a 47-bp common (core) sequence, and the core of attR was located in 3' region of a potential tRNA(Arg) gene. These results suggested that (i) attL and attR are phage-host junctions, left- and right-arms, respectively, (ii) attP is a phage attachment site, and (iii) intgaY is an integrase gene for phage integration and/or excision. After mitomycin C-induction, phage particles were demonstrated by electron microscopy. The prophage (phigaY) is somewhat leaky in the host, and has the two-component lysis system (HolgaY-LysgaY), closely resembling that of Lj928 as well as Lj965.
    No preview · Article · May 2005 · International Journal of Food Microbiology

  • No preview · Article · Jan 2005 · Microbes and Environments
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    ABSTRACT: The cellular slime mold Dictyostelium discoideum expresses a gene encoding a 452-amino-acid polypeptide that is 47% identical to Escherichia coli RecA. A recA-deficient E. coli, JE6651, was transformed by pYSN1, which was designed to express the truncated form of the D. discoideum gene, and used in suppression assays. The viability of the transformant, JE6651(pYSN1), increased following UV irradiation or mitomycin C treatment. Phage lambda (red(-) gam(-)), which required RecA activity for DNA packaging, formed plaques on a lawn of JE6651(pYSN1). These results indicate that the gene product has a DNA recombination activity. Fluorescence of D. discoideum protein fused with GFP was detected in mitochondria. The gene disruption mutant was hypersensitive to UV-light (254nm), mitomycin C and H(2)O(2), indicating that D. discoideum recA is important for survival following exposure to DNA damaging agents.
    No preview · Article · Jun 2004 · DNA Repair
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    ABSTRACT: The cellular slime mold Dictyostelium discoideum expresses three genes (sodA, sodB and sodC) encoding the extracellular Cu/Zn superoxide dismutases. Following H(2)O(2) treatment, the expression of sodA and sodB increased while that of sodC decreased. The sodC null strain formed multinucleate cells in a shaking culture. These results suggest that sodC plays a unique role in Dictyostelium discoideum.
    Preview · Article · Sep 2003 · Biological & Pharmaceutical Bulletin
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    ABSTRACT: Lactobacillus plantarum temperate phage phi g1e encodes a major virion protein gpP. In the present study, the gpP protein was overproduced in Escherichia coli under plac, and purified. Like the native-gpP protein from phi gle particles (Kakikawa et al., 1996), the purified-gpP protein had an apparent molecular mass of 26.0 kDa on SDS polyacrylamide gel electrophoresis (PAGE), larger than that (18.8 kDa) predicted from the DNA sequence, and was deficient in the first methionine as revealed by the N-terminal protein sequencing. In addition, analysis by immunoelectron microscopy demonstrated that immunogold particles (associated with antigpP-sera) specifically bound to the tails of phi gle particles, indicating that gpP is a main tail component (putatively a tube protein).
    No preview · Article · Jul 2002 · The Journal of Biochemistry Molecular Biology and Biophysics
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    ABSTRACT: Lactobacillus plantarum phage phi gle has two consecutive cell lysis genes hol-lys (Oki et al., 1996b). In the present study, functional and structural properties of the hol protein (Hol) were characterized in Escherichia coli. Electron microscopic examinations showed that hol under plac in E. coli XL1-Blue injured the inner membrane to yield empty ghost cells with the bulk of the cell wall undisturbed. Northern blot analysis indicated that hol-lys genes under plac were co-transcribed, although the amount of hol transcript was larger than that of lys, ceasing via an apparently rho-independent terminator just downstream of hol. However, deletion and/or fusion experiments suggested that: (1) the N-terminal half of phi gle Hol composed of three putative transmembrane domains may be responsible for interaction with membrane; (2) the N-terminal end (five amino acids) seems nonessential; and (3) the C-terminal half containing charged amino acids appears to be involved in proper hol function. These results suggest that phi gle Hol is a member of the lambdoid holin family, but divergent in several properties from lambda holin.
    No preview · Article · Oct 1997 · Gene
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    ABSTRACT: Bacteriophage phi gle was induced from a lysogenic Lactobacillus strain Gle. phi gle genome is double-stranded DNA of approximately 42.5 kilo-base (kb) pairs. SDS poly-acrylamide gel electrophoresis demonstrated that the phage particles contain 4 major structural (capsid) proteins, gpB, gpG, gpO, and gpP, whose molecular weights (MW) are estimated to be 64, 43, 29 and 26 kilodaltons (kDa), respectively. More than 16 minor proteins ranging from 113 to 9.6 kDa were also detected. The genes for the major capsid proteins were cloned and each DNA sequence was determined. N-terminal amino acid alignments determined by protein sequencing completely coincided with those deduced from the nucleotide sequences.
    No preview · Article · Nov 1996 · Gene