title: Bacillus anthracis SlaQ Promotes S-Layer Protein Assembly.
abstract: Bacillus anthracis vegetative forms assemble an S-layer comprised of two S-layer proteins, Sap and EA1. A hallmark of S-layer proteins are their C-terminal crystallization domains, which assemble into a crystalline lattice once these polypeptides are deposited on the bacterial surface via association between their N-terminal S-layer homology domains and the secondary cell wall polysaccharide. Here we show that slaQ, encoding a small cytoplasmic protein conserved among pathogenic bacilli elaborating S-layers, is required for the efficient secretion and assembly of Sap and EA1. S-layer protein precursors cosediment with SlaQ, and SlaQ appears to facilitate Sap assembly. Purified SlaQ polymerizes and when mixed with purified Sap promotes the in vitro formation of tubular S-layer structures. A model is discussed whereby SlaQ, in conjunction with S-layer secretion factors SecA2 and SlaP, promotes localized secretion and S-layer assembly in B. anthracis.
  
  
  OBJECTIVE
  S-layer proteins are endowed with the propensity for self-assembly into crystalline arrays. Factors promoting S-layer protein assembly have heretofore not been reported. We identified Bacillus anthracis SlaQ, a small cytoplasmic protein that facilitates S-layer protein assembly in vivo and in vitro.
authors.affiliation: Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA.
authors.forename: Sao-Mai
authors.initials: SM
authors.lastname: Nguyen-Mau
authors.affiliation: Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Oh
authors.affiliation: Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA.
authors.forename: Daphne I
authors.initials: DI
authors.lastname: Schneewind
authors.affiliation: Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA.
authors.forename: Dominique
authors.initials: D
authors.lastname: Missiakas
authors.affiliation: Howard Taylor Ricketts Laboratory, Argonne National Laboratory, Lemont, Illinois, USA Department of Microbiology, University of Chicago, Chicago, Illinois, USA oschnee@bsd.uchicago.edu.
authors.forename: Olaf
authors.initials: O
authors.lastname: Schneewind
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial; D001408:Bacillus anthracis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D011232:Chemical Precipitation; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D011817:Rabbits; D000097573:Red Fluorescent Protein
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D000097573:Red Fluorescent Protein; C055764:S-layer proteins