1gvn
From Proteopedia
Crystal Structure of the Plasmid Maintenance System epsilon/zeta: Meachnism of toxin inactivation and toxin function
Structural highlights
Function[EATX_STRPY] Antitoxin component of a toxin-antitoxin (TA) module. Neutralizes the toxic effect of cognate zeta toxin. Part of a postsegregational killing (PSK) system involved in the killing of plasmid-free cells. Continuous synthesis of the epsilon antitoxin is required to counteract the zeta toxin.[REFERENCE:7] [ZTOX_STRPY] Toxic component of a toxin-antitoxin (TA) module. Phosphorylates UDP-N-acetyl-D-glucosamine (UNAG) on the 3'-hydroxyl group of the N-acetyl-D-glucosamine moiety, yielding UNAG-3P. UNAG-3P inhibits MurA, the first committed step in cell wall synthesis, which is then blocked. Phosphorylation is inhibited by cognate epsilon antitoxin. Part of a postsegregational killing (PSK) system involved in the killing of plasmid-free cells. The zeta toxin induces programmed cell death.[REFERENCE:7] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedProgrammed 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. References
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