Disease relevance of cvaB

• Extracellular secretion of the peptide antibiotic colicin V (ColV) in Escherichia coli is mediated by a dedicated exporter system consisting of host TolC protein and the products of two specific genes, cvaA and cvaB, the latter being a member of the ATP binding cassette (ABC) superfamily [1].
• The three Erwinia protease export proteins can also export active ColV, and interference is seen when CvaA or CvaB is expressed along with the intact Prt exporter [2].

High impact information on cvaB

• The extracellular secretion of the antibacterial toxin colicin V is mediated via a signal sequence independent process which requires the products of two linked genes: cvaA and cvaB [3].
• The nucleotide sequence of cvaB reveals that its product is a member of a subfamily of proteins, involved in the export of diverse molecules, found in both eukaryotes and prokaryotes [3].
• Together with comparisons of the sequences of members of the cysteine protease family, these results indicate that Cys32 and His105 are the critical residues in the CvaB N-terminal domain for the calcium-dependent cysteine protease activity and secretion of colicin V [4].
• The cytoplasmic membrane protein CvaB, involved in colicin V secretion in Escherichia coli, belongs to the ABC-transporter family in which ATP hydrolysis is typically the driving force for substrate transport [5].
• These included sitABCD, genes of the aerobactin operon, hlyF, iss, genes of the salmochelin operon, and the 5' end of cvaB of the ColV operon [6].

Biological context of cvaB

• Nucleotide binding was shown to be critical for CvaB CTD dimerization [7].
• Interactions of dedicated export membrane proteins of the colicin V secretion system: CvaA, a member of the membrane fusion protein family, interacts with CvaB and TolC [8].
• Moreover, a point mutation (D654H) in CvaB that completely abolishes colicin V secretion severely impairs both GTPase and ATPase activities in the corresponding BCTD, indicating that the two activities are from the same enzyme [9].

Anatomical context of cvaB

• As a member of the membrane fusion protein family, CvaA is supposed to form a bridge that connects the inner and outer membranes via interaction with CvaB and TolC, respectively [8].

Associations of cvaB with chemical compounds

• Cys32 and His105 in the N-terminal domain of CvaB were identified as critical residues for both colicin V secretion and cysteine proteolytic activity [4].

Analytical, diagnostic and therapeutic context of cvaB

• Sequence alignment and homology modeling of the CvaB nucleotide-binding domain predicted that the aromatic stacking region of CvaB (Y501DSQ loop) had a role in the differential binding of nucleotides, and Ser503 and Gln504 provided potential hydrogen bonds to GTP but not to ATP [5].
• Different forms of the CvaB CTD were found during purification and identified as monomer, dimer, and oligomer forms by gel filtration and protein cross-linking [7].

References