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Publication Abstract from PubMed

Programmed cell death in prokaryotes is frequently found as postsegregational killing. It relies on antitoxin/toxin systems that secure stable inheritance of low and medium copy number plasmids during cell division and kill cells that have lost the plasmid. The broad-host-range, low-copy-number plasmid pSM19035 from Streptococcus pyogenes carries the genes encoding the antitoxin/toxin system epsilon/zeta and antibiotic resistance proteins, among others. The crystal structure of the biologically nontoxic epsilon(2)zeta(2) protein complex at a 1.95-A resolution and site-directed mutagenesis showed that free zeta acts as phosphotransferase by using ATPGTP. In epsilon(2)zeta(2), the toxin zeta is inactivated because the N-terminal helix of the antitoxin epsilon blocks the ATPGTP-binding site. To our knowledge, this is the first prokaryotic postsegregational killing system that has been entirely structurally characterized.

Crystal structure of the plasmid maintenance system epsilon/zeta: functional mechanism of toxin zeta and inactivation by epsilon 2 zeta 2 complex formation.,Meinhart A, Alonso JC, Strater N, Saenger W Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):1661-6. Epub 2003 Feb 5. PMID:12571357^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.