Role of unsaturated fatty acid biosynthesis in virulence of Streptococcus mutans.

Department of Microbiology and Immunology, Center for Oral Biology, Rochester, NY 14642, USA.
Infection and Immunity (Impact Factor: 4.16). 04/2007; 75(3):1537-9. DOI: 10.1128/IAI.01938-06
Source: PubMed

ABSTRACT An insertionally inactivated fabM strain of Streptococcus mutans does not produce unsaturated membrane fatty acids and is acid sensitive (E. M. Fozo and R. G. Quivey, Jr., J. Bacteriol. 186:4152-4158, 2004). In this study, the strain was shown to be poorly transmissible from host to host. Animals directly infected with the fabM strain exhibited fewer and less severe carious lesions than those observed in the wild-type strain.

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    ABSTRACT: SMU.1745c, encoding a putative transcriptional regulator of the MarR family, maps to a location proximal to the fab gene cluster in Streptococcus mutans. Deletion of the SMU.1745c (fabTSm) coding region resulted in a membrane fatty acid composition comprised of longer-chained, unsaturated fatty acids (UFA), when compared to the parent strain. Previous reports have indicated a role for FabT in regulation of genes in the fab gene cluster in other organisms, via binding to a palindromic DNA sequence (Lu & Rock, 2006, Eckhardt et al., 2013). Consensus FabT motif sequences were identified in S. mutans in the intergenic regions preceding fabM, fabTSm, and fabK in the fab gene cluster. Chloramphenicol acetyltransferase (cat) reporter fusions, using the fabM promoter, revealed elevated transcription in a ∆fabTSm background. Transcription of fabTSm was dramatically elevated in cells grown at pH values of 5 and 7 in the ∆ fabTSm background. Transcription of fabTSm was also elevated in a strain carrying a deletion for the carbon catabolite repressor CcpA. Purified FabTSm and CcpA bound to the promoter regions of fabTSm and fabM. Thus, the data indicate that FabTSm acts as a repressor of fabM and fabTSm itself and the global regulator, CcpA, acts as a repressor for fabTSm.This article is protected by copyright. All rights reserved.
    08/2014; 30(2). DOI:10.1111/omi.12076
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    ABSTRACT: The oral cariogenic bacterial pathogen Streptococcus mutans strain UA159 has become an important research organism strain since its genome was sequenced. However, there is a paucity of information on its lipidome using direct analytical biochemical approaches. We here report on comprehensive analyses of the major lipid classes and their fatty acids in cells grown in batch standing cultures. Using 2-D high-performance thin-layer chromatography lipid class composition changes were detected with culture age. More lipid components were detected in the stationary-phase compared to log-phase cells. The major lipids identified included 1,3-bis(sn-3'-phosphatidyl)-sn-glycerol (phosphatidylglycerol), 1,3-diphosphatidylglycerol (cardiolipin), aminoacyl-phosphatidylglycerol, monoglucosyldiacylglycerol, diglucosyldiacylglycerol, diglucosylmonoacylglycerol and, glycerophosphoryldiglucosyldiacylglycerol. Culture age also affected the fatty acid composition of the total polar lipid fraction. Thus, the major lipid classes detected in log-phase and stationary-phase cells were isolated and their fatty acids were analyzed by gas-liquid chromatography to determine the basis for the fatty acid compositional changes in the total polar lipid fraction. The analyses showed that the relative proportions of these acids changed with culture age within individual lipid classes. Hence fatty acid changes in the total polar lipid fraction reflected changes in both lipid class composition and fatty acid compositions within individual lipid classes.
    Lipids 04/2014; 49(6). DOI:10.1007/s11745-014-3904-9 · 2.35 Impact Factor
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    ABSTRACT: Background Metagenomics is a relatively new but fast growing field within environmental biology and medical sciences. It enables researchers to understand the diversity of microbes, their functions, cooperation, and evolution in a particular ecosystem. Traditional methods in genomics and microbiology are not efficient in capturing the structure of the microbial community in an environment. Nowadays, high-throughput next-generation sequencing technologies are powerfully driving the metagenomic studies. However, there is an urgent need to develop efficient statistical methods and computational algorithms to rapidly analyze the massive metagenomic short sequencing data and to accurately detect the features/functions present in the microbial community. Although several issues about functions of metagenomes at pathways or subsystems level have been investigated, there is a lack of studies focusing on functional analysis at a low level of a hierarchical functional tree, such as SEED subsystem tree. Results A two-step statistical procedure (metaFunction) is proposed to detect all possible functional roles at the low level from a metagenomic sample/community. In the first step a statistical mixture model is proposed at the base of gene codons to estimate the abundances for the candidate functional roles, with sequencing error being considered. As a gene could be involved in multiple biological processes the functional assignment is therefore adjusted by utilizing an error distribution in the second step. The performance of the proposed procedure is evaluated through comprehensive simulation studies. Compared with other existing methods in metagenomic functional analysis the new approach is more accurate in assigning reads to functional roles, and therefore at more general levels. The method is also employed to analyze two real data sets. Conclusions metaFunction is a powerful tool in accurate profiling functions in a metagenomic sample.
    PLoS ONE 09/2014; 9(9):e106588. DOI:10.1371/journal.pone.0106588 · 3.53 Impact Factor

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