Regulation of Asymmetry and Polarity During the
            <i>Caulobacter</i>
            Cell Cycle

The highly conserved SMC (Structural Maintenance of Chromosomes) proteins function in chromosome condensation, segregation, and other aspects of chromosome dynamics in both eukaryotes and prokaryotes. A null mutation in the Caulobacter crescentus smc gene is conditionally lethal and causes a cell cycle arrest at the predivisional cell stage. Chromosome segregation in wild-type and smc null mutant cells was examined by monitoring the intracellular localization of the replication origin and terminus by using f luorescence in situ hybridization. In wild-type cells, the origin is located at the f lagellated pole of swarmer cells and, immediately after the initiation of DNA replication in stalked cells, one of the origins moves to the opposite pole, giving a bipolar localization of the origins. The terminus moves from the end of the swarmer cell opposite the origin to midcell. A subpopulation of the smc null mutant cells had mislocalized origins or termini, showing that the smc null mutation gives DNA segregation defects. Nucleoid morphology was also abnormal. Thus, we propose that the Caulobacter chromosomal origins have specific cellular addresses and that the SMC protein plays important roles in maintaining chromosome structure and in partitioning. The specific cell cycle arrest in the smc null mutant indicates the presence of a cell cycle checkpoint that senses perturbations in chromosome organization or segregation.

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Isolation and characterization of a xylose-dependent promoter from Caulobacter crescentus

Meisenzahl

1997

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An inducible promoter is a useful tool for the controlled expression of a given gene. Accordingly, we identified, cloned, and sequenced a chromosomal locus, xylX, from Caulobacter crescentus which is required for growth on xylose as the sole carbon source and showed that transcription from a single site is dependent on the presence of xylose in the growth medium. P xylX promoter activity was determined as a function of the composition of the growth medium both in single copy and on a plasmid using different reporter genes. One hundred micromolar exogenously added xylose was required for maximal induction of P xylX in a strain that is unable to metabolize xylose. P xylX activity was induced immediately after the addition of xylose and repressed almost completely when xylose was removed from the growth medium. In addition to the strong transcriptional control, the expression of xylX is also regulated on the translational level.

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Regulation of Asymmetry and Polarity During the Caulobacter Cell Cycle

Cited by 4 publications

References 161 publications

Bacterial cells: The migrating kinase and the master regulator

Bacterial cells: The migrating kinase and the master regulator

The Caulobacter crescentus smc gene is required for cell cycle progression and chromosome segregation

Isolation and characterization of a xylose-dependent promoter from Caulobacter crescentus

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