Bacillus anthracis SlaQ Promotes S-Layer Protein Assembly

Nguyen-Mau, Sao-Mai; Oh, So-Young; Schneewind, Daphne I.; Missiakas, Dominique; Schneewind, Olaf

doi:10.1128/jb.00492-15

Cited by 9 publications

(12 citation statements)

References 55 publications

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“…Mutations that abrogate expression of sap cause B. anthracis to form elongated chains owing to the mislocalization of the murein hydrolase BslO (64). Screening libraries of mutant bacilli for variants with increased chain length led to the identification of three genes: secA2 , slaP , and slaQ (102, 103). These genes are located immediately adjacent to the S-layer gene cluster ( csaA-csaB-sap-eag ) (103) (Figure 2).…”

Section: Secretion and Assembly Of S-layer Proteinsmentioning

confidence: 99%

“…Screening libraries of mutant bacilli for variants with increased chain length led to the identification of three genes: secA2 , slaP , and slaQ (102, 103). These genes are located immediately adjacent to the S-layer gene cluster ( csaA-csaB-sap-eag ) (103) (Figure 2). Mutations in all three genes diminish the abundance of Sap and EA1 in the bacterial S-layer but do not affect the secretion of other products (102).…”

Section: Secretion and Assembly Of S-layer Proteinsmentioning

confidence: 99%

“…Mutations in all three genes diminish the abundance of Sap and EA1 in the bacterial S-layer but do not affect the secretion of other products (102). Mutations in secA2 and slaP , but not in slaQ , diminish the secretion of mCherry hybrids fused to the N-terminal signal peptide and SLH domains of Sap (103). In contrast, mutations in slaQ affect only the secretion of mCherry hybrids fused to full-length Sap including the C-terminal crystallization domain (103).…”

Section: Secretion and Assembly Of S-layer Proteinsmentioning

confidence: 99%

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Assembly and Function of the Bacillus anthracis S-Layer

Missiakas

Schneewind

2017

Annu. Rev. Microbiol.

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Bacillus anthracis, the anthrax agent, is a member of the Bacillus cereus sensu lato group, which includes invasive pathogens of mammals or insects as well as nonpathogenic environmental strains. The genes for anthrax pathogenesis are located on two large virulence plasmids. Similar virulence plasmids have been acquired by other B. cereus strains and enable the pathogenesis of anthrax-like diseases. Among the virulence factors of B. anthracis is the S-layer-associated protein BslA, which endows bacilli with invasive attributes for mammalian hosts. BslA surface display and function are dependent on the bacterial S-layer, whose constituents assemble by binding to the secondary cell wall polysaccharide (SCWP) via S-layer homology (SLH) domains. B. anthracis and other pathogenic B. cereus isolates harbor genes for the secretion of S-layer proteins, for S-layer assembly, and for synthesis of the SCWP. We review here recent insights into the assembly and function of the S-layer and the SCWP.

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Section: Secretion and Assembly Of S-layer Proteinsmentioning

confidence: 99%

Section: Secretion and Assembly Of S-layer Proteinsmentioning

confidence: 99%

Section: Secretion and Assembly Of S-layer Proteinsmentioning

confidence: 99%

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Assembly and Function of the Bacillus anthracis S-Layer

Missiakas

Schneewind

2017

Annu. Rev. Microbiol.

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“…The ketal-pyruvyl-modified SCWP is a ligand for the S-layer homology (SLH) domains of native B. anthracis proteins. These include the S-layer proteins Sap and EA1, which assemble into a paracrystalline S-layer (22)(23)(24), as well as B. anthracis S-layer-associated proteins (BSLs) that fulfill the specific functions of host cell adhesion (25), nutrient transport (26), and cell separation and chain length determination (27). To identify the genetic determinants for SCWP synthesis, we combined experimental and bioinformatic approaches and identified two factors, WpaA and WpaB, that belong to the heretofore-uncharacterized PF13425 family; PF13425 is one of five protein families in CL0499, a clan that also includes bacterial membrane proteins involved in the assembly of O-antigen lipopolysaccharide (LPS).…”

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confidence: 99%

Genes Required for Bacillus anthracis Secondary Cell Wall Polysaccharide Synthesis

Lunderberg

Château

et al. 2017

J Bacteriol

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The secondary cell wall polysaccharide (SCWP) is thought to be essential for vegetative growth and surface (S)-layer assembly in Bacillus anthracis; however, the genetic determinants for the assembly of its trisaccharide repeat structure are not known. Here, we report that WpaA (BAS0847) and WpaB (BAS5274) share features with membrane proteins involved in the assembly of O-antigen lipopolysaccharide in Gram-negative bacteria and propose that WpaA and WpaB contribute to the assembly of the SCWP in B. anthracis. Vegetative forms of the B. anthracis wpaA mutant displayed increased lengths of cell chains, a cell separation defect that was attributed to mislocalization of the S-layer-associated murein hydrolases BslO, BslS, and BslT. The wpaB mutant was defective in vegetative replication during early logarithmic growth and formed smaller colonies. Deletion of both genes, wpaA and wpaB, did not yield viable bacilli, and when depleted of both wpaA and wpaB, B. anthracis could not maintain cell shape, support vegetative growth, or assemble SCWP. We propose that WpaA and WpaB fulfill overlapping glycosyltransferase functions of either polymerizing repeat units or transferring SCWP polymers to linkage units prior to LCP-mediated anchoring of the polysaccharide to peptidoglycan. IMPORTANCE The secondary cell wall polysaccharide (SCWP) is essential for Bacillus anthracis growth, cell shape, and division. SCWP is comprised of trisaccharide repeats (¡4)-␤-ManNAc-(1¡4)-␤-GlcNAc-(1¡6)-␣-GlcNAc-(1¡) with ␣-Gal and ␤-Gal substitutions; however, the genetic determinants and enzymes for SCWP synthesis are not known. Here, we identify WpaA and WpaB and report that depletion of these factors affects vegetative growth, cell shape, and S-layer assembly. We hypothesize that WpaA and WpaB are involved in the assembly of SCWP prior to transfer of this polymer onto peptidoglycan.KEYWORDS Bacillus anthracis, S-layers, Wzy repeat polymerase, cell wall polysaccharide, envelope assembly T he peptidoglycan cell wall of Gram-positive microbes is a determinant of bacterial shape and integrity (1, 2). Peptidoglycan also serves as a scaffold for the attachment of secondary polymers, which support specific cell cycle functions of bacteria (3, 4). Some Gram-positive bacteria, for example, Bacillus subtilis and Staphylococcus aureus, attach wall teichoic acid (WTA) to peptidoglycan, thereby positioning peptidoglycan synthesis enzymes, division septa, and murein hydrolases for cell growth and division (5-7). Other microbes, including Streptococcus species and Bacillus cereus, attach a secondary cell wall polysaccharide (SCWP) to peptidoglycan, and these polymers presumably fulfill functions similar to that of WTA during the bacterial cell cycle (8, 9). While WTA synthesis has been studied in detail (10), little is known about the genetic determinants and assembly reactions for SCWP synthesis.

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“…4). On the other hand, Sap and EA1 are transported across the bacterial envelope by a unique secretory pathway, defined by-products of the secA2, slaP, and slaQ genes (39,50). Also, mutations that affect Sap S-layer protein expression impact the distribution of the other S-layer (EA1) and S-layer-associated proteins (BSLs) in the envelope; these observations imply that abundant secretion and assembly of Sap blocks sites on the SCWP that then cannot be occupied by other SLH domain proteins (the preferred seating model) (33).…”

Section: Discussionmentioning

confidence: 99%

Bacillus anthracis tagO Is Required for Vegetative Growth and Secondary Cell Wall Polysaccharide Synthesis

et al. 2015

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Bacillus anthracis elaborates a linear secondary cell wall polysaccharide (SCWP) that retains surface (S)-layer and associated proteins via their S-layer homology (SLH) domains. The SCWP is comprised of trisaccharide repeats [¡4)-␤-ManNAc-(1¡4)-␤-GlcNAc-(1¡6)-␣-GlcNAc-(1¡]and tethered via acid-labile phosphodiester bonds to peptidoglycan. Earlier work identified UDP-GlcNAc 2-epimerases GneY (BAS5048) and GneZ (BAS5117), which act as catalysts of ManNAc synthesis, as well as a polysaccharide deacetylase (BAS5051), as factors contributing to SCWP synthesis. Here, we show that tagO (BAS5050), which encodes a UDP-N-acetylglucosamine:undecaprenyl-P N-acetylglucosaminyl 1-P transferase, the enzyme that initiates the synthesis of murein linkage units, is required for B. anthracis SCWP synthesis and S-layer assembly. Similar to gneY-gneZ mutants, B. anthracis strains lacking tagO cannot maintain cell shape or support vegetative growth. In contrast, mutations in BAS5051 do not affect B. anthracis cell shape, vegetative growth, SCWP synthesis, or S-layer assembly. These data suggest that TagO-mediated murein linkage unit assembly supports SCWP synthesis and attachment to the peptidoglycan via acid-labile phosphodiester bonds. Further, B. anthracis variants unable to synthesize SCWP trisaccharide repeats cannot sustain cell shape and vegetative growth. IMPORTANCEBacillus anthracis elaborates an SCWP to support vegetative growth and envelope assembly. Here, we show that some, but not all, SCWP synthesis is dependent on tagO-derived murein linkage units and subsequent attachment of SCWP to peptidoglycan. The data implicate secondary polymer modifications of peptidoglycan and subcellular distributions as a key feature of the cell cycle in Gram-positive bacteria and establish foundations for work on the molecular functions of the SCWP and on inhibitors with antibiotic attributes.T he cell wall envelope of Bacillus anthracis, the causative agent of anthrax, is comprised of peptidoglycan and its attached secondary cell wall polysaccharide (SCWP) (1). The SCWP retains two surface (S)-layer proteins, surface array protein (Sap) and extractable antigen 1 (EA1) (2), as well as 22 S-layer-associated proteins whose S-layer homology (SLH) domains associate with ketal-pyruvylated SCWP (3, 4). Unlike nonpathogenic Bacillus spp., for example, Bacillus subtilis and Bacillus cereus AHU1030, B. anthracis does not synthesize wall teichoic acid (WTA) (5, 6). Nevertheless, B. anthracis expresses functional tagO and tagA genes, whose products provide for the synthesis of murein linkage units [P-GlcNAc-(4¡1)-␤-ManNAc-R] that are phosphodiester linked to the C 6 -hydroxyl of N-acetylmuramic acid in the repeating disaccharide of peptidoglycan [MurNAc(P-GlcNAc-ManNAc-R)-GlcNAc] (4). In B. subtilis, -R represents wall teichoic acid, i.e., either polyglycerol-phosphate or polyribitol-phosphate (7). Here, we test the hypothesis that in B. anthracis the SCWP is attached via the murine linkage unit and that the tagO gene is required for vegetati...

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Bacillus anthracis SlaQ Promotes S-Layer Protein Assembly

Cited by 9 publications

References 55 publications

Assembly and Function of the Bacillus anthracis S-Layer

Assembly and Function of the Bacillus anthracis S-Layer

Genes Required for Bacillus anthracis Secondary Cell Wall Polysaccharide Synthesis

Bacillus anthracis tagO Is Required for Vegetative Growth and Secondary Cell Wall Polysaccharide Synthesis

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