Functional Analysis of Glucan Binding Protein B from
            <i>Streptococcus mutans</i>

Mattos-Graner, Renata O.; Porter, Kristen A.; Smith, Daniel J.; Hosogi, Yumiko; Duncan, Marilyn J.

doi:10.1128/jb.01845-05

Cited by 51 publications

(73 citation statements)

References 51 publications

(56 reference statements)

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“…Changes in the pH of the growth medium are known to induce complex regulatory networks, as well as differential expression of multiple genes, including those involved with metabolism of sugars (26). It was previously shown that expression of gbpB, which encodes glucan-binding protein B, is altered under low-pH conditions (29). Expression of gbpC was reduced at low pH, comparable to gbpB expression in strain UA159.…”

Section: Vol 189 2007 Gbpc Expression In S Mutans 6527mentioning

confidence: 74%

Regulation of gbpC Expression in Streptococcus mutans

2007

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Streptococcus mutans, the principal causative agent of dental caries, produces four glucan-binding proteins (Gbp) that play major roles in bacterial adherence and pathogenesis. One of these proteins, GbpC, is an important cell surface protein involved in biofilm formation. GbpC is also important for cariogenesis, bacteremia, and infective endocarditis. In this study, we examined the regulation of gbpC expression in S. mutans strain UA159. We found that gbpC expression attains the maximum level at mid-exponential growth phase, and the half-life of the transcript is less than 2 min. Expression from PgbpC was measured using a PgbpC-gusA transcriptional fusion reporter and was analyzed under various stress conditions, including thermal, osmotic, and acid stresses. Expression of gbpC is induced under conditions of thermal stress but is repressed during growth at low pH, whereas osmotic stress had no effect on expression from PgbpC. The results from the expression analyses were further confirmed using semiquantitative reverse transcription-PCR analysis. Our results also reveal that CovR, a global response regulator in many Streptococcus spp., represses gbpC expression at the transcriptional level. We demonstrated that purified CovR protein binds directly to the promoter region of PgbpC to repress gbpC expression. Using a DNase I protection assay, we showed that CovR binds to DNA sequences surrounding PgbpC from bases ؊68 to 28 (where base 1 is the start of transcription). In summary, our results indicate that various stress conditions modulate the expression of gbpC and that CovR negatively regulates the expression of the gbpC gene by directly binding to the promoter region.

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Section: Vol 189 2007 Gbpc Expression In S Mutans 6527mentioning

confidence: 74%

Regulation of gbpC Expression in Streptococcus mutans

2007

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“…Monocistronic expression was previously reported for gbpB Smu , which is the pcsB homologue in S. mutans (37). Recently, it was proposed that GbpB Smu is not a cell division protein at all but rather coordinates exopolysaccharide biofilm formation with cell growth and surface biogenesis (14).…”

Section: Discussionmentioning

confidence: 99%

The Requirement for Pneumococcal MreC and MreD Is Relieved by Inactivation of the Gene Encoding PBP1a

2011

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Three basic patterns of peptidoglycan (PG) synthesis have emerged from the study of rod-shaped (bacillus), spherical (coccus), and ellipsoid (ovococcus) bacteria (reviewed in references 12, 71, and 72). In rod-shaped bacteria, like Escherichia coli, Bacillus subtilis, and Caulobacter crescentus, PG synthesis occurs at two locations catalyzed by distinct sets of proteins (12,35,36,71). Lateral PG synthesis elongates the side walls of these bacteria and results in their rod shape (12,35,71). Lateral PG synthesis is mediated by actin-like MreB paralogue proteins, which form filamentous helical structures in spirals over the length of cells (12,35,66). MreB is thought to organize the MreC and MreD proteins, which in turn recruit specific penicillin-binding proteins (PBPs) and other division proteins that catalyze lateral PG formation (26,54,55,70). Septal PG synthesis is organized by FtsZ ring formation, followed by the orderly assembly of the divisome complex, which includes a set of PBPs different from those involved in lateral PG synthesis (16,22,23). The mutational interruption of lateral or septal PG synthesis of rod-shaped bacteria generally results in the formation of spherical or elongated cells, respectively (3, 4, 9, 31). Although useful, this two-state model is obviously an oversimplification (35), and recent results reveal that MreB, MreC, MreD, and specific PBPs also form annular rings adjacent to FtsZ rings at the septa of dividing E. coli cells (67). Moreover, some PBPs and division regulators, such as PBP1 and GpsB of B. subtilis, shuttle between the lateral and septal PG synthesis machineries (9).Much less is known about the mechanisms of PG synthesis in coccus and ovococcus species. In spherical species, such as Staphylococcus aureus, only a septal PG synthesis machinery seems to be present (20,47,72), although S. aureus still encodes homologues of proteins like MreC and MreD that mediate lateral PG synthesis in rod-shaped bacteria (35). In contrast, ovococcus species, such as Streptococcus pneumoniae and Lactococcus lactis, form American football-shaped cells by a combination of peripheral sidewall and septal PG synthesis that occurs in the midcell regions of dividing cells (Fig. 1) (11,42). Ovococcus species lack an MreB homologue, and peripheral and septal PG synthesis are likely coordinated with and organized by FtsZ ring formation (64,65,72). Because two modes of PG biosynthesis are required to form ellipsoidshaped bacteria, models have been proposed for two different PG synthesis machineries (18,21,33,72). Based on the composition of the complexes in rod-shaped cells, it has been hypothesized that specific sets of homologous cell division proteins mediate peripheral (MreC, MreD, RodA, and PBP2b) and septal (FtsZ, EzrA, PBP2x, FtsW, and DivIB/FtsL/DivIC) PG synthesis in ovococcus bacteria (72). A recent study correlating the effects of mutations or antibiotic treatments to changes in cell shapes supports the idea that the PBP2x and PBP2b class B transpeptidases are associated with septal and p...

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“…The first is that AtlA can directly mediate intercellular adhesion. Notably, the glucan binding protein B (GbpB) of S. mutans was reported to share homology with a putative peptidoglycan hydrolase from group B streptococcus (14,49,50). The possession of the large repeat regions, such as those found in AtlA, is characteristic of surface proteins involved in ligand binding, and the peptidoglycan hydrolase domain may also mediate cell wall binding, possibly in a more complex manner.…”

Section: Discussionmentioning

confidence: 99%

The atlA Operon of Streptococcus mutans : Role in Autolysin Maturation and Cell Surface Biogenesis

Ahn

Burne

2006

J Bacteriol

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The Smu0630 protein (AtlA) was recently shown to be involved in cell separation, biofilm formation, and autolysis. Here, transcriptional studies revealed that atlA is part of a multigene operon under the control of at least three promoters. The morphology and biofilm-forming capacity of a nonpolar altA mutant could be restored to that of the wild-type strain by adding purified AtlA protein to the medium. A series of truncated derivatives of AtlA revealed that full activity required the C terminus and repeat regions. AtlA was cell associated and readily extractable from with sodium dodecyl sulfate. Of particular interest, the surface protein profile of AtlA-deficient strains was dramatically altered compared to the wild-type strain, as was the nature of the association of the multifunctional adhesin P1 with the cell wall. In addition, AtlA-deficient strains failed to develop competence as effectively as the parental strain. Mutation of thmA, which can be cotranscribed with atlA and encodes a putative pore-forming protein, resulted in a phenotype very similar to that of the AtlAdeficient strain. ThmA was also shown to be required for efficient processing of AtlA to its mature form, and treatment of the thmA mutant strain with full-length AtlA protein did not restore normal cell separation and biofilm formation. The effects of mutating other genes in the operon on cell division, biofilm formation, or AtlA biogenesis were not as profound. This study reveals that AtlA is a surface-associated protein that plays a critical role in the network connecting cell surface biogenesis, biofilm formation, genetic competence, and autolysis.Bacteria produce a variety of enzymes involved in the modification and degradation of peptidoglycan, including N-acetyglucosaminidases, N-acetylmuramidases, N-acetylmuramyl-Lalanine amidases, endopeptidases, and transglycosylases (31,54,71,80). Some of these enzymes are known as autolysins because they digest the cell wall when cells are exposed to unfavorable conditions (70,71,80). The presence of these enzymes may not be sufficient for lysis, and additional factors may be required to activate or regulate the activity of the autolysins (44), presumably to protect the cells from the lytic activity of the enzymes. Peptidoglycan hydrolases have also been demonstrated to play critical roles in cell wall turnover, cell growth, antibiotic resistance, cell-to-surface adhesion, genetic competence, and protein secretion (9,23,28,51,74), as well as contributing to virulence (8, 86). In many bacteria, a correlation of a lack of peptidoglycan hydrolase(s) activity and a failure in cell separation has been reported (35,60,77,87).An increasing number of peptidoglycan hydrolases have been identified in gram-positive bacteria, including Bacillus subtilis (37,39,48,59,74), Lactococcus lactis (11,12,22,34,75), Listeria monocytogenes (57, 79, 86), Staphylococcus aureus (19,36,53,78), Enterococcus faecalis (15,16,55,56,72,73), and Streptococcus pneumoniae (8,18,20,83). Recently, during a search for surface prote...

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Functional Analysis of Glucan Binding Protein B from Streptococcus mutans

Cited by 51 publications

References 51 publications

Regulation of gbpC Expression in Streptococcus mutans

Regulation of gbpC Expression in Streptococcus mutans

The Requirement for Pneumococcal MreC and MreD Is Relieved by Inactivation of the Gene Encoding PBP1a

The atlA Operon of Streptococcus mutans : Role in Autolysin Maturation and Cell Surface Biogenesis

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