Disease relevance of cbpA

• The cbpA chaperone gene function compensates for dnaJ in lambda plasmid replication during amino acid starvation of Escherichia coli [1].
• The mutational lesions characteristic of a dnaJ null mutant--namely, temperature sensitivity for growth and defects in lambda phage and mini-F DNA replication--were all restored upon introduction of the cbpA gene on a multicopy plasmid [2].
• The cbpA gene is in an operon with an open reading frame, yccD, which encodes a protein that has some homology to DafA of Thermus thermophilus [3].

High impact information on cbpA

• The cbpA gene functions as a multicopy suppressor for dnaJ mutations [2].
• An insertional mutant of cbpA was also isolated, which showed no noticeable phenotype, particularly with regard to temperature sensitivity for growth [2].
• The structure of this sigma s-dependent cbpA promoter was clarified by determining its transcription start site [4].
• The cbpA promoter region was found to contain an unusual DNA structure (i.e. DNA curvature) [4].
• Sequence analyses of the S. typhimurium scs genes and adjacent DNAs revealed that the scs locus is flanked by genes with high homology to the cbpA (predicted curved DNA-binding protein) and agp (acid glucose phosphatase) genes of E. coli located at 22.90 min (1,062.07 kb) and 22.95 min (1,064.8 kb) of the E. coli chromosome, respectively [5].

Biological context of cbpA

• In particular, the cbpA dnaJ double-null mutant was found to exhibit severe defects in cell growth, namely, a very narrow temperature range for growth, a defect in cell division, and susceptibility to killing by carbon starvation [6].
• To gain insight into the functions of CbpA as well as DnaJ, we isolated a multicopy suppressor gene that permits this dnaJ- cbpA- mutant to grow normally at low temperatures [7].
• A portion of the cbpA gene from Escherichia coli K-12 encoding a 24 amino acid proton-buffering peptide (Pbp) was cloned via the shuttle vector pJB99 into E. coli JM105 and subsequently into Zymomonas mobilis CP4 [8].

References