Jonathan M. Budzik

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The cell wall envelope of Gram-positive bacteria can be thought of as a surface organelle for the assembly of macromolecular structures that enable the unique lifestyle of each microorganism. Sortases - enzymes that cleave the sorting signals of secreted proteins to form isopeptide (amide) bonds between the secreted proteins and peptidoglycan or(More)
Vegetative forms of Bacillus cereus are reported to form pili, thin protein filaments that protrude up to 1 mum from the bacterial surface. Pili are assembled from two precursor proteins, BcpA and BcpB, in a manner requiring a pilus-associated sortase enzyme (SrtD). Pili are also formed on the surface of Bacillus anthracis expressing bcpA-srtD-bcpB. BcpA is(More)
Gram-positive bacteria elaborate pili and do so without the participation of folding chaperones or disulfide bond catalysts. Sortases, enzymes that cut pilin precursors, form covalent bonds that link pilin subunits and assemble pili on the bacterial surface. We determined the x-ray structure of BcpA, the major pilin subunit of Bacillus cereus. The BcpA(More)
There is increasing evidence that bacterial biofilms play a role in a variety of ocular infections. Bacterial growth is characterized as a biofilm when bacteria attach to a surface and/or to each other. This is distinguished from a planktonic or free-living mode of bacterial growth where these interactions are not present. Biofilm formation is a genetically(More)
Bacillus cereus G9241 causes an anthrax-like respiratory illness in humans; however, the molecular mechanisms of disease pathogenesis are not known. Genome sequencing identified two putative virulence plasmids proposed to provide for anthrax toxin (pBCXO1) and/or capsule expression (pBC218). We report here that B. cereus G9241 causes anthrax-like disease in(More)
Assembly of pili in Gram-positive bacteria and their attachment to the cell wall envelope are mediated by sortases. In Bacillus cereus and its close relative Bacillus anthracis, the major pilin protein BcpA is cleaved between the threonine and the glycine of its C-terminal LPXTG motif sorting signal by the pilin-specific sortase D. The resulting acyl enzyme(More)
Pilin precursors are the building blocks of pili on the surface of Gram-positive bacteria; however, the assembly mechanisms of these adhesive fibers are unknown. Here, we describe the chemical bonds that assemble BcpA pilin subunits on the surface of Bacillus cereus. Sortase D cleaves BcpA precursor between the threonine (T) and the glycine (G) residues of(More)
Bacillus cereus and other Gram-positive bacteria elaborate pili via a sortase D-catalyzed transpeptidation mechanism from major and minor pilin precursor substrates. After cleavage of the LPXTG sorting signal of the major pilin, BcpA, sortase D forms an amide bond between the C-terminal threonine and the amino group of lysine within the YPKN motif of(More)
Bacillus cereus strains elaborate pili on their surface using a mechanism of sortase-mediated cross-linking of major and minor pilus components. Here we used a combination of electron microscopy and atomic force microscopy to visualize these structures. Pili occur as single, double or higher order assemblies of filaments formed from monomers of the major(More)
BACKGROUND Nocardia farcinica is a gram-positive, partially acid-fast, methenamine silver-positive aerobic actinomycete. Nocardia spp. are opportunistic pathogens, and N. farcinica is the least common species of clinical importance. METHODS Review of the recent literature and description of a immunocompetent patient with no known risk factors who(More)