Complete genome sequence of Caulobacter crescentus

Abstract

The complete genome sequence of Caulobacter crescentus was determined to be 4,016,942 base pairs in a single circular chromosome encoding 3,767 genes. This organism, which grows in a dilute aquatic environment, coordinates the cell division cycle and multiple cell differentiation events. With the annotated genome sequence, a full description of the genetic network that controls bacterial differentiation, cell growth, and cell cycle progression is within reach. Two-component signal transduction proteins are known to play a significant role in cell cycle progression. Genome analysis revealed that the C. crescentus genome encodes a significantly higher number of these signaling proteins (105) than any bacterial genome sequenced thus far. Another regulatory mechanism involved in cell cycle progression is DNA methylation. The occurrence of the recognition sequence for an essential DNA methylating enzyme that is required for cell cycle regulation is severely limited and shows a bias to intergenic regions. The genome contains multiple clusters of genes encoding proteins essential for survival in a nutrient poor habitat. Included are those involved in chemotaxis, outer membrane channel function, degradation of aromatic ring compounds, and the breakdown of plant-derived carbon sources, in addition to many extracytoplasmic function sigma factors, providing the organism with the ability to respond to a wide range of environmental fluctuations. C. crescentus is, to our knowledge, the first free-living α-class proteobacterium to be sequenced and will serve as a foundation for exploring the biology of this group of bacteria, which includes the obligate endosymbiont and human pathogen Rickettsia prowazekii , the plant pathogen Agrobacterium tumefaciens , and the bovine and human pathogen Brucella abortus .

Genetic Analysis of a Novel Pathway for d -Xylose Metabolism in Caulobacter crescentus

“…The gene in which this insertion is located, designated "xylX" by Meisenzahl et al (18) and later "CC0823" in the C. crescentus genome annotation (19), does not closely resemble any gene of known function. xylX is the first gene in a xylose-inducible operon (CC0823-CC0819) (12), referred to here as the xyl operon.…”

“…The xylA gene product was annotated by the C. crescentus genome project as a "short-chain aldehyde dehydrogenase," while the xylB product was annotated as an "oxidoreductase" (19). To determine whether XDH activity is attributable to one of these gene products, the PCR-amplified coding regions were cloned separately into the pCR-CT-T7-Topo expression vector to allow production of C-terminal His-tagged proteins in E. coli strain BL21( DE3) pLysS (Invitrogen).…”

“…Roughly 20,000 Kan r isolates were screened. Using chromosomal DNA as the template and primers derived from the Tn5 sequence, mutants with growth defects were analyzed by cycle sequencing to determine the location of the transposon insertion in comparison with that of the C. crescentus genome sequence (19). Strains unable to use glucose but unaffected in xylose utilization had mutations in genes previously implicated in glucose catabolism (12), including components of the Entner-Doudoroff (E-D) pathway ( Fig.…”

Isolation and characterization of Caulobacter mutants impaired in adaptation to stationary phase

“…The recombinant plasmids were used for automatic DNA sequencing with BigDye terminators on a ABI Prism 377 sequencer (AP Biosystems). The insertion site was determined by comparison to the complete C. crescentus genome sequence (19).…”

“…crescentus is an aquatic bacterium belonging to the alpha subfamily of the proteobacteria, and no homolog of σ S was identified in the genome sequence (19), suggesting that the regulation of stationary phase genes could be carried out by a different system. A previous work showed that when in late stationary phase Caulobacter undergoes a morphological change and display increased resistance to stress (29).…”