, 2007; Mahmoud & Koval, 2010). This is also the case ALK inhibitor for the cytoskeletal MreB proteins, whose alteration does have a marked effect on the subsequent progression of the predatory cycle, but not upon the initial invasion of prey (Fenton et al., 2010). The question as to whether cytoskeletal proteins or peptidoglycan interactions are key to allowing B. bacteriovorus cells to be dragged into prey by pilus retraction remains open. Our results suggest that while Ccrp in B. bacteriovorus does not contribute to the vibroid cell shape, it significantly contributes to the smoothness of the B. bacteriovorus cell shape by acting as an internal protein scaffold. We thank C.J. Wagner for her
initial identification of a coiled-coil containing protein in Bdellovibrio, Cezar Khusugaria for advice and assistance with Ferroptosis phosphorylation the cryoelectron microscopy on the Tecnai Polara TEM and Marilyn Whitworth for technical assistance. This study was funded by a BBSRC PhD Studentship for A.K.F. to R.E.S., HFSP grant RGP57/2005 to
R.E.S. for L.H. and NIH core funding to S.S. for C.B. A.K.F. carried out the majority of the experiments, designed parts of the experimental programme including the mTFP fusions and coauthored the paper. L.H. constructed the Bd2345∷Kn B. bacteriovorus control strain, assisted with TEM analysis and critically read the manuscript. C.B. and A.K.F. carried out cryoelectron microscopic analysis under the supervision of S.S., and R.E.S. designed the experimental programme, supervised the research, coauthored and revised the paper. “
“The main steps in the biosynthesis of complex secondary metabolites such as the antibiotic kirromycin are catalyzed by modular polyketide synthases (PKS) and/or nonribosomal peptide synthetases (NRPS). During antibiotic assembly, the biosynthetic intermediates ADP ribosylation factor are attached to carrier protein domains of these megaenzymes via a phosphopantetheinyl arm. This functional group of the carrier proteins is attached
post-translationally by a phosphopantetheinyl transferase (PPTase). No experimental evidence exists about how such an activation of the carrier proteins of the kirromycin PKS/NRPS is accomplished. Here we report on the characterization of the PPTase KirP, which is encoded by a gene located in the kirromycin biosynthetic gene cluster. An inactivation of the kirP gene resulted in a 90% decrease in kirromycin production, indicating a substantial role for KirP in the biosynthesis of the antibiotic. In enzymatic assays, KirP was able to activate both acyl carrier protein and petidyl carrier domains of the kirromycin PKS/NRPS. In addition to coenzyme A (CoA), which is the natural substrate of KirP, the enzyme was able to transfer acyl-phosphopantetheinyl groups to the apo forms of the carrier proteins.