Article
Complete genome sequence of the ureolytic Streptococcus salivarius strain 57.I.
The CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100029 Beijing, People’s Republic of China.
Journal of bacteriology (impact factor:
3.94).
10/2011;
193(19):5596-7.
DOI:10.1128/JB.05670-11
pp.5596-7
Source: PubMed
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Article: Identification and characterization of the nickel uptake system for urease biogenesis in Streptococcus salivarius 57.I.
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ABSTRACT: Ureases are multisubunit enzymes requiring Ni(2+) for activity. The low pH-inducible urease gene cluster in Streptococcus salivarius 57.I is organized as an operon, beginning with ureI, followed by ureABC (structural genes), and ureEFGD (accessory genes). Urease biogenesis also requires a high-affinity Ni(2+) uptake system. By searching the partial genome sequence of a closely related organism, Streptococcus thermophilus LMG18311, three open reading frame (ORFs) homologous to those encoding proteins involved in cobalamin biosynthesis and cobalt transport (cbiMQO) were identified immediately 3' to the ure operon. To determine whether these genes were involved in urease biogenesis by catalyzing Ni(2+) uptake in S. salivarius, regions 3' to ureD were amplified by PCRs from S. salivarius by using primers identical to the S. thermophilus sequences. Sequence analysis of the products revealed three ORFs. Reverse transcriptase PCR was used to demonstrate that the ORFs are transcribed as part of the ure operon. Insertional inactivation of ORF1 with a polar kanamycin marker completely abolished urease activity and the ability to accumulate (63)Ni(2+) during growth. Supplementation of the growth medium with NiCl(2) at concentrations as low as 2.5 micro M partially restored urease activity in the mutant. Both wild-type and mutant strains showed enhanced urease activity when exogenous Ni(2+) was provided at neutral pH. Enhancement of urease activity by adding nickel was regulated at the posttranslational level. Thus, ORF1, ORF2, and ORF3 are part of the ure operon, and these genes, designated ureM, ureQ, and ureO, respectively, likely encode a Ni(2+)-specific ATP-binding cassette transporter.Journal of Bacteriology 01/2004; 185(23):6773-9. · 3.83 Impact Factor -
Article: Streptococcus salivarius urease: genetic and biochemical characterization and expression in a dental plaque streptococcus.
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ABSTRACT: The hydrolysis of urea by urease enzyme of oral bacteria is believed to have a major impact on oral microbial ecology and to be intimately involved in oral health and diseases. To begin to understand the biochemistry and genetics of oral ureolysis, a study of the urease of Streptococcus salivarius, a highly ureolytic organism which is present in large numbers on the soft tissues of the oral cavity, has been initiated. By using as a probe a 0.6-kpb internal fragment of the S. salivarius 57.I ureC gene, two clones from subgenomic libraries of S. salivarius 57.I in an Escherichia coli plasmid vector were identified. Nucleotide sequence analysis revealed the presence of one partial and six complete open reading frames which were most homologous to ureIAB-CEFGD of other ureolytic bacteria. Plasmid clones were generated to construct a complete gene cluster and used to transform E. coli and Streptococcus gordonii DL1, a nonureolytic, dental plaque microorganism. The recombinant organisms expressed high levels of urease activity when the growth medium was supplemented with NiCl2. The urease enzyme was purified from E. coli, and its biochemical properties were compared with those of the urease produced by S. salivarius and those of the urease produced by S. gordonii carrying the plasmid-borne ure genes. In all cases, the enzyme had a Km of 3.5 to 4.1 mM, a pH optimum near 7.0, and a temperature optimum near 60 degrees C. S. gordonii carrying the urease genes was then demonstrated to have a significant capacity to temper glycolytic acidification in vitro in the presence of concentrations of urea commonly found in the oral cavity. The ability to genetically engineer plaque bacteria that can modulate environmental pH through ureolysis will open the way to using recombinant ureolytic organisms to test hypotheses regarding the role of oral ureolysis in dental caries, calculus formation, and periodontal diseases. Such recombinant organisms may eventually prove useful for controlling dental caries by replacement therapy.Infection and Immunity 03/1996; 64(2):585-92. · 4.16 Impact Factor -
Article: cadDX operon of Streptococcus salivarius 57.I.
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ABSTRACT: A CadDX system that confers resistance to Cd(2+) and Zn(2+) was identified in Streptococcus salivarius 57.I. Unlike with other CadDX systems, the expression of the cad promoter was negatively regulated by CadX, and the repression was inducible by Cd(2+) and Zn(2+), similar to what was found for CadCA systems. The lower G+C content of the S. salivarius cadDX genes suggests acquisition by horizontal gene transfer.Applied and environmental microbiology 04/2008; 74(5):1642-5. · 3.69 Impact Factor
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Keywords
Complete genome sequencing
human mouth
S. salivarius 57.I
sole nitrogen source
Streptococcus salivarius 57.I
ureolytic bacteria
