Prokaryotic Development: Emerging Insights

Abstract

2The city of Quebec, Canada, was a splendid setting for the ASM Conference on Prokaryotic Development, which was convened on 10 to 14 July 2002. Approximately 220 participants were treated to 39 talks and 128 poster presentations describing the latest insights into developmental processes in a variety of bacteria. Scientific program organizers Y. Brun (Indiana University) and L. Shimkets (University of Georgia), together with their advisory committee (M. Bibb, Diversa; J. Errington, University of Oxford; J. Golden, Texas A&M University; H. Kaplan, University of Texas-Houston; and L. Shapiro, Stanford University), planned seven sessions of talks on the topics of differential gene expression, positional information, checkpoints, signaling, cell cycle control, morphogenesis, and multicellularity. This topical format was effective in emphasizing common themes that have emerged from studies of different organisms. Each session featured two speakers invited prior to abstract submission and three to five speakers selected from among those who submitted abstracts. This format provided a lively mix of speakers that included established and young principal investigators, postdocs, and graduate students. Participants were also invited to submit manuscripts related to their abstracts for review and possible inclusion in this issue of the Journal of Bacteriology.In this review, we describe highlights of the meeting, focusing mainly on the talks and to a lesser extent on related information from poster presentations. We generally follow the order of topics as presented at the meeting, but we have combined information from the sessions on signaling and multicellularity. Also, some talks presented in one session at the meeting are described here under a different topic. In keeping with the purpose of the meeting, we attempt to identify shared features of the molecular mechanisms that regulate and produce developmental change in different prokaryotes. Such features include networks of interacting regulators governing transcription, proteins that localize to a subcellular domain and then relocalize or rapidly oscillate to determine placement of a structure, proteolysis to activate or eliminate a key protein, self-assembling proteins that build structures inside cells to maintain shape or on the surface of cells for movement, adherence, or protection, and signaling between cells to coordinate movement and differentiation of the population. We also point out unique features of the developmental processes of different microbes and unanswered questions that make each worthy of continued study.

FtsZ Collaborates with Penicillin Binding Proteins To Generate Bacterial Cell Shape inEscherichia coli

“…Any model for the mechanism that creates bacterial shape must now take into account the role of PBP 5 (30,31), the involvement of peptidoglycan endopeptidases, the generation and mislocalization of patches of inert peptidoglycan (12,32), the participation of MreB (9,17,22,24), and the influence of FtsZ. So far, the data can be accommodated in a generalized morphological pathway in which FtsZ or an FtsZ-dependent process acts on the cell wall to synthesize metabolically inert peptidoglycan (iPG), whose spatial distribution would dictate the overall geometry of the growing cell (44).…”

“…On one hand, experiments suggest that peptidoglycan-synthesizing enzymes may be attached to internal filamentous scaffolds of MreB or Mbl proteins (9,17,22,24), whose geometric distribution determines the cylindrical form of the bacterium. How these cytoskeletons assume their own forms, how they transduce this information to the cell wall, and what determines the original size and shape of the cylinder are open questions.…”

patS Minigenes Inhibit Heterocyst Development of Anabaena sp. Strain PCC 7120

“…(17,20). Receptor molecules for these signals may be present either outside the cell or within the cytoplasm.…”

Helical Disposition of Proteins and Lipopolysaccharide in the Outer Membrane ofEscherichia coli

“…The MreB and Mbl proteins form such fibrils, or cables, in Bacillus subtilis (22) and Caulobacter crescentus (17) and may serve as internal scaffolds that position peptidoglycan-synthesizing enzymes, thereby defining the shape of the cell wall (17,29,33). The MinCD proteins oscillate from pole to pole along helical paths, inhibiting polymerization of the principal cell division protein FtsZ and helping to define the cell's center (56).…”