Oh So-Young, Lunderberg J Mark, Chateau Alice, Schneewind Olaf, Missiakas Dominique
Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA, and Department of Microbiology, University of Chicago, Chicago, Illinois, USA.
Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA, and Department of Microbiology, University of Chicago, Chicago, Illinois, USA
J Bacteriol. 2016 Dec 13;199(1). doi: 10.1128/JB.00613-16. Print 2017 Jan 1.
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.
The secondary cell wall polysaccharide (SCWP) is essential for Bacillus anthracis growth, cell shape, and division. SCWP is comprised of trisaccharide repeats (→4)-β-ManNAc-(1→4)-β-GlcNAc-(1→6)-α-GlcNAc-(1→) with α-Gal and β-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.
人们认为次生细胞壁多糖（SCWP）对于炭疽芽孢杆菌的营养生长和表面（S）层组装至关重要；然而，其具有三糖重复结构的组装的遗传决定因素尚不清楚。在此，我们报告WpaA（BAS0847）和WpaB（BAS5274）与参与革兰氏阴性菌O抗原脂多糖组装的膜蛋白具有共同特征，并提出WpaA和WpaB有助于炭疽芽孢杆菌中SCWP的组装。炭疽芽孢杆菌wpaA突变体的营养形式显示细胞链长度增加，这是一种细胞分离缺陷，归因于与S层相关的胞壁质水解酶BslO、BslS和BslT的定位错误。wpaB突变体在对数生长早期的营养复制中存在缺陷，并形成较小的菌落。wpaA和wpaB这两个基因的缺失不会产生有活力的杆菌，并且当wpaA和wpaB都被耗尽时，炭疽芽孢杆菌无法维持细胞形状、支持营养生长或组装SCWP。我们提出WpaA和WpaB履行重叠的糖基转移酶功能，即要么聚合重复单元，要么在LCP介导的多糖与肽聚糖锚定之前将SCWP聚合物转移到连接单元上。
次生细胞壁多糖（SCWP）对于炭疽芽孢杆菌的生长、细胞形状和分裂至关重要。SCWP由三糖重复序列（→4）-β-甘露糖胺-（1→4）-β-葡萄糖胺-（1→6）-α-葡萄糖胺-（1→）组成，并带有α-半乳糖和β-半乳糖取代；然而，SCWP合成的遗传决定因素和酶尚不清楚。在此，我们鉴定出WpaA和WpaB，并报告这些因子的耗尽会影响营养生长、细胞形状和S层组装。我们假设WpaA和WpaB在将这种聚合物转移到肽聚糖之前参与SCWP的组装。
