A histidine protein kinase is involved in polar organelle development in Caulobacter crescentus.

Abstract

Mutations having pleiotropic effects on polar organelle development (pod) in Caulobacter crescentus have been identified and shown to occur in at least 13 genes scattered throughout the genome. Mutations at each locus affect a unique combination of polar traits, suggesting that complex interactions occur among these genes. The DNA sequence of one of these genes, pkeC, indites that it is homologous to members of the family of histidine protein kinase genes. Members of this family include the sensor components of the bacterial twocomponent regulatory systems. Furthermore, in vitro experiments demonstrated that the PleC protein was capable of autophosphorylation. These results suggest that the PieC protein (and perhaps the proteins encoded by the other pod genes as well) regulates the expes of genes involved in polar organelle development through the phosphorylation of key regulatory proteins. The use of a phosphorelay system cued to internal changes in the cell would provide a mechanis for coordinating major changes in gene expression with the completion of specific cell cycle events.Differentiation in Caulobacter crescentus is observed as an ordered series of events at the poles of the cell. Each cell division results in two cell types, a stalked cell like the parent and a motile swarmer cell. The two new poles formed at cell division lack polar organelles, while the older poles contain polar organelles produced during previous rounds of differentiation. After cell division, DNA replication is initiated immediately in the stalked progeny cell, followed by the assembly of a set of polar organelles including a flagellum, pili, and phage receptors at the newly created pole. The resulting predivisional cell has a different set of organelles at each pole, the original stalk at one end and the flagellum, pili, and phage receptors at the other.After a period of motility, the swarmer cell releases the flagellum into the culture medium, and the remainder of the polar organelles are replaced by a stalk. An exception is the holdfast material, which is found at the base of the flagellum.

Isolation and characterization of multiple adenylate cyclase genes from the cyanobacterium Anabaena sp. strain PCC 7120

“…The histidine kinase-like domain of CyaC (Leu-511 to Leu-729) is similar to the transmitter domain of histidine kinase proteins. This region of CyaC shows 27.9% identity to the LemA protein of Pseudomonas syringae (23), 32.4% identity to the PhoR protein of Shigella dysenteriae (30), 26.0% identity to the RcsC protein of E. coli (24), and 33.3% identity to the PleC protein of Caulobacter crescentus (50). The highly conserved histidine residue of histidine kinase proteins and the aspartate residue of response regulator proteins, both of which are responsible for protein phosphorylation, exist in regions of CyaC (His-524, Asp-59, and Asp-847).…”

A membrane metalloprotease participates in the sequential degradation of a Caulobacter polarity determinant

“…Synchronization and bacteriophage FCr30-mediated generalized transductions were performed as described (Evinger and Agabian, 1977;Ely, 1991). Rosette formation was determined by phase contrast microscopy in CB15 derivatives, chemotaxis was assayed on PYE and M2-glucose (M2G) semisolid media, and the presence of pili was assessed by sensitivity to bacteriophage FCbK, as previously described (Wang et al, 1993;Viollier et al, 2002a). Escherichia coli strains were grown at 30 or 37∞C in Luria-Bertani (LB) medium (Miller, 1972) or M9 minimal medium (Ausubel et al, 1988), with the appropriate antibiotics: ampicillin (100 mg ml -1 ), carbenicillin (50 mg ml -1 ), chloramphenicol (20 mg ml -1 ), kanamycin (50 mg ml -1 ), spectinomycin (50 mg ml -1 ), and/or oxytetracycline (12 mg ml -1 ).…”

Rapid diversification of coevolving marine Synechococcus and a virus

“…LPS is also involved in bacteriophage attachment in WH7803 (36). The two additional mutations were found in genes encoding a glycosyltransferase, which could be involved in LPS biosynthesis (37), and a histidine kinase, which could regulate proteins exposed outside the cell wall to which viruses attach (38) (Table S3).…”