Affiliation:
1. Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA, and Department of Microbiology, University of Chicago, Chicago, Illinois, USA
Abstract
ABSTRACT
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)-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.
Funder
HHS | NIH | National Institute of Allergy and Infectious Diseases
HHS | NIH | National Institute of General Medical Sciences
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
17 articles.
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