Domains Required for Transcriptional Activation Show Conservation in the Mga Family of Virulence Gene Regulators

Vahling, Cheryl M.; McIver, Kevin S.

doi:10.1128/jb.188.3.863-873.2006

Cited by 22 publications

(23 citation statements)

References 29 publications

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“…Both helix-turn-helix domains are also present in the Mga (7) and AtxA (8) global response regulators. In Mga, such domains were shown to be required for DNA binding and transcriptional activation (28,29). …”

Section: Discussionmentioning

confidence: 99%

The pneumococcal MgaSpn virulence transcriptional regulator generates multimeric complexes on linear double-stranded DNA

Solano-Collado

Espinosa

Bravo

2013

Nucleic Acids Research

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The MgaSpn transcriptional regulator contributes to the virulence of Streptococcus pneumoniae. It is thought to be a member of the Mga/AtxA family of global regulators. MgaSpn was shown to activate in vivo the P1623B promoter, which is divergent from the promoter (Pmga) of its own gene. This activation required a 70-bp region (PB activation region) located between both promoters. In this work, we purified an untagged form of the MgaSpn protein, which formed dimers in solution. By gel retardation and footprinting assays, we analysed the binding of MgaSpn to linear double-stranded DNAs. MgaSpn interacted with the PB activation region when it was placed at internal position on the DNA. However, when it was positioned at one DNA end, MgaSpn recognized preferentially the Pmga promoter placed at internal position. In both cases, and on binding to the primary site, MgaSpn spread along the adjacent DNA regions generating multimeric protein–DNA complexes. When both MgaSpn-binding sites were located at internal positions on longer DNAs, electron microscopy experiments demonstrated that the PB activation region was the preferred target. DNA molecules totally or partially covered by MgaSpn were also visualized. Our results suggest that MgaSpn might recognize particular DNA conformations to achieve DNA-binding specificity.

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Section: Discussionmentioning

confidence: 99%

The pneumococcal MgaSpn virulence transcriptional regulator generates multimeric complexes on linear double-stranded DNA

Solano-Collado

Espinosa

Bravo

2013

Nucleic Acids Research

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“…Only WxL locus A encoded a protein with an LPxTG-like motif (Fms6), analogous to CscD (7). Locus A and locus C both are associated with Mga-like transcriptional regulators, which often are regulators of virulence genes important for colonization and immune evasion (38). Directly upstream of locus B is a LytR-family transcriptional regulator which has been shown to be involved in extracellular polysaccharide biosynthesis, fimbriation, expression of exoproteins, and cell autolysis (39).…”

Section: Resultsmentioning

confidence: 99%

The Identification and Functional Characterization of WxL Proteins from Enterococcus faecium Reveal Surface Proteins Involved in Extracellular Matrix Interactions

Galloway-Peña

Liang²,

Singh

et al. 2015

J Bacteriol

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fThe WxL domain recently has been identified as a novel cell wall binding domain found in numerous predicted proteins within multiple Gram-positive bacterial species. However, little is known about the function of proteins containing this novel domain. Here, we identify and characterize 6 Enterococcus faecium proteins containing the WxL domain which, by reverse transcription-PCR (RT-PCR) and genomic analyses, are located in three similarly organized operons, deemed WxL loci A, B, and C. Western blotting, electron microscopy, and enzyme-linked immunosorbent assays (ELISAs) determined that genes of WxL loci A and C encode antigenic, cell surface proteins exposed at higher levels in clinical isolates than in commensal isolates. Secondary structural analyses of locus A recombinant WxL domain-containing proteins found they are rich in ␤-sheet structure and disordered segments. Using Biacore analyses, we discovered that recombinant WxL proteins from locus A bind human extracellular matrix proteins, specifically type I collagen and fibronectin. Proteins encoded by locus A also were found to bind to each other, suggesting a novel cell surface complex. Furthermore, bile salt survival assays and animal models using a mutant from which all three WxL loci were deleted revealed the involvement of WxL operons in bile salt stress and endocarditis pathogenesis. In summary, these studies extend our understanding of proteins containing the WxL domain and their potential impact on colonization and virulence in E. faecium and possibly other Gram-positive bacterial species. Enterococcus faecium is one of the "no ESKAPE" pathogens responsible for a considerable percentage of nosocomial infections; its ability to cause life-threatening infections and resistance to antibiotics cause considerable difficulties for patients and physicians (1). To date, many of the potential virulence determinants that have been described in E. faecium are MSCRAMMs (microbial surface components recognizing adhesive matrix molecules); these include adhesins or pili anchored to the cell surface by an LPxTG-like motif and contain IgG-like folds (2). Our group previously performed a bioinformatic search for novel surface proteins that might be virulence factors in the E. faecium endocarditis strain TX16 (also known as DO) (3). During this search, we identified a locus which included predicted proteins possessing the previously described WxL domain colocated with a predicted LPxTG-like protein (Fms6) (3, 4).The WxL domain is comprised of several conserved residues along with a highly conserved YXXX(L/I/V)TWXLXXXP motif and a second WxL proximal motif in the last ϳ120 to 190 C-terminal residues of a protein (4,5). Genes encoding proteins with the WxL domain were first described in Lactobacillus plantarum as part of a novel gene cluster found in a subset of low-GϩC-content Gram-positive bacterial species, one of which is E. faecium (6, 7). Bioinformatics and transcriptome data in L. plantarum predicted these loci form cell surface protein complexes involved in ca...

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“…In Mga, two helix-turn-helix domains were mapped near the N terminus of the protein. Both of them are known to be required for DNA binding and transcriptional activation (24,36). In addition, Mga is known to bind to regions located upstream of its target promoters.…”

Section: Discussionmentioning

confidence: 99%

Activator Role of the Pneumococcal Mga-Like Virulence Transcriptional Regulator

2012

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Global transcriptional regulators that respond to specific environmental signals are crucial in bacterial pathogenesis. In the case of the Gram-positive pathogen Streptococcus pneumoniae (the pneumococcus), the sp1800 gene of the clinical isolate TIGR4 encodes a protein that exhibits homology to the Mga "stand-alone" response regulator of the group A Streptococcus. Such a pneumococcal protein was shown to play a significant role in both nasopharyngeal colonization and development of pneumonia in murine infection models. Moreover, it was shown to repress the expression of several genes located within the rlrA pathogenicity islet. The pneumococcal R6 strain, which derives from the D39 clinical isolate, lacks the rlrA islet but has a gene (here named mga Spn ) equivalent to the sp1800 gene. In this work, and using in vivo approaches, we have identified the promoter of the mga Spn gene (Pmga) and demonstrated that four neighboring open reading frames of unknown function (spr1623 to spr1626) constitute an operon. Transcription of this operon is under the control of two promoters (P1623A and P1623B) that are divergent from the Pmga promoter. Furthermore, we have shown that the Mga Spn protein activates the P1623B promoter in vivo. This activation requires sequences located around 50 to 120 nucleotides upstream of the P1623B transcription start site. By DNase I footprinting assays, we have also demonstrated that such a region includes an Mga Spn binding site. This is the first report on the activator role of the pneumococcal Mga-like protein.

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Domains Required for Transcriptional Activation Show Conservation in the Mga Family of Virulence Gene Regulators

Cited by 22 publications

References 29 publications

The pneumococcal MgaSpn virulence transcriptional regulator generates multimeric complexes on linear double-stranded DNA

The pneumococcal MgaSpn virulence transcriptional regulator generates multimeric complexes on linear double-stranded DNA

The Identification and Functional Characterization of WxL Proteins from Enterococcus faecium Reveal Surface Proteins Involved in Extracellular Matrix Interactions

Activator Role of the Pneumococcal Mga-Like Virulence Transcriptional Regulator

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