title: The scaffolding and signalling functions of a localization factor impact polar development.
abstract: In the differentiating alphaproteobacterium Caulobacter crescentus, organelle synthesis at cell poles is critical to forming different progeny after cell division. Co-ordination of polar organelle synthesis, including pili and holdfast, and flagellum ejection, is mediated in part by the scaffolding protein PodJ. At the time of cell division, PodJ undergoes regulated processing to a short form that persists at the flagellar pole of swarmer cells. This study analyses how PodJ's role in structural and signalling protein localization impacts organelle synthesis. A PodJ mutant with an internal deletion exhibits reduced sensitivity to pili-tropic phage ΦCbK, resulting from reduced pilA gene expression, which can be linked to altered signalling protein localization. The phage sensitivity defect of a ΔpodJ mutant can be partially suppressed by ectopic pilA expression. Induction of PodJ processing, by manipulation of podJ itself or controlled perP expression, resulted in decreased pilus biogenesis and, when coupled with a podJ mutation that reduced pilA expression, led to complete loss of phage sensitivity. As a whole, the results show that PodJ's scaffolding role for structural and signalling proteins both contribute to flagellar pole organelle development.
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Curtis
authors.forename: Ellen M
authors.initials: EM
authors.lastname: Quardokus
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Lawler
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Guo
authors.forename: David
authors.initials: D
authors.lastname: Klein
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Chen
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Arnold
authors.forename: Yves V
authors.initials: YV
authors.lastname: Brun
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001435:Bacteriophages / Q000254:growth & development; D016935:Caulobacter crescentus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division; D010861:Fimbriae, Bacterial / Q000502:physiology*; D015870:Gene Expression; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D017384:Sequence Deletion; D013489:Suppression, Genetic
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C120058:podj protein, Caulobacter crescentus