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Structural highlights

Function

CCDB_ECOLI Toxic component of a toxin-antitoxin (TA) module, functioning in plasmid maintainence. Responsible for the post-segregational killing (PSK) of plasmid-free cells, also referred to as a plasmid addiction system. Half-life of over 2 hours. Cell killing by CcdB is accompanied by filamentation, defects in chromosome and plasmid segregation, defects in cell division, formation of anucleate cells, decreased DNA synthesis and plasmid loss. Interferes with the activity of DNA gyrase, inducing it to form a covalent GyrA-DNA complex that cannot be resolved, thus promoting breakage of plasmid and chromosomal DNA. DNA breakage requires hydrolyzable ATP. Toxicity is inhibited by labile antitoxin CcdA, which blocks the activity of CcdB; CcdA also removes bound CcdB protein from the CcdB-GyrA complex by forming a CcdA-CcdB complex, a process termed rejuvenation. Also acts to inhibit partitioning of the chromosomal DNA. Functions as a transcriptional corepressor for the ccdAB operon, repression also requires CcdA.^{[1] [2] [3] [4] [5] [6]}

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

References

1. ↑ Miki T, Yoshioka K, Horiuchi T. Control of cell division by sex factor F in Escherichia coli. I. The 42.84-43.6 F segment couples cell division of the host bacteria with replication of plasmid DNA. J Mol Biol. 1984 Apr 25;174(4):605-25. PMID:6327993
2. ↑ Tam JE, Kline BC. Control of the ccd operon in plasmid F. J Bacteriol. 1989 May;171(5):2353-60. PMID:2651399
3. ↑ Ogura T, Hiraga S. Mini-F plasmid genes that couple host cell division to plasmid proliferation. Proc Natl Acad Sci U S A. 1983 Aug;80(15):4784-8. PMID:6308648
4. ↑ Tam JE, Kline BC. The F plasmid ccd autorepressor is a complex of CcdA and CcdB proteins. Mol Gen Genet. 1989 Oct;219(1-2):26-32. PMID:2615761
5. ↑ Bernard P, Couturier M. Cell killing by the F plasmid CcdB protein involves poisoning of DNA-topoisomerase II complexes. J Mol Biol. 1992 Aug 5;226(3):735-45. PMID:1324324
6. ↑ Maki S, Takiguchi S, Horiuchi T, Sekimizu K, Miki T. Partner switching mechanisms in inactivation and rejuvenation of Escherichia coli DNA gyrase by F plasmid proteins LetD (CcdB) and LetA (CcdA). J Mol Biol. 1996 Mar 1;256(3):473-82. PMID:8604132 doi:http://dx.doi.org/10.1006/jmbi.1996.0102