title: The trans-acting flagellar regulatory proteins, FliX and FlbD, play a central role in linking flagellar biogenesis and cytokinesis in Caulobacter crescentus.
abstract: The FliX/FlbD-dependent temporal transcription of late flagellar genes in Caulobacter crescentus requires the assembly of an early, class II-encoded flagellar structure. Class II flagellar-mutant strains exhibit a delay in the completion of cell division, with the accumulation of filamentous cells in culture. It is shown here that this cell-division defect is attributable to an arrest in the final stages of cell separation. Normal cell morphology could be restored in class II mutants by gain-of-function alleles of FliX or FlbD, suggesting that the timely completion of cell division requires these trans-acting factors. In synchronized cultures, inhibition of cell division by depleting FtsZ resulted in normal initial expression of the late, FlbD-dependent fliK gene; however, the cell cycle-regulated cessation of transcription was delayed, indicating that cell division may be required to negatively regulate FlbD activity. Interestingly, prolonged depletion of FtsZ resulted in an eventual loss of FlbD activity that could be bypassed by a constitutive mutant of FlbD, but not of FliX, suggesting the possible existence of a second cell cycle-dependent pathway for FlbD activation.
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, CA 90095-1569, USA.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Muir
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, CA 90095-1569, USA.
authors.forename: Jesse
authors.initials: J
authors.lastname: Easter
authors.affiliation: Department of Chemistry and Biochemistry and Molecular Biology Institute, University of California, Los Angeles, CA 90095-1569, USA.
authors.forename: James W
authors.initials: JW
authors.lastname: Gober
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000166:cytology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D002455:Cell Division; D048749:Cytokinesis; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; C089631:FlbD protein, Caulobacter crescentus; C111943:FliX protein, Caulobacter crescentus; C071525:FtsZ protein, Bacteria; D008565:Membrane Proteins