Zeta toxin protein domain explained

In molecular biology, the protein domain Zeta (ζ) toxin refers to a protein domain found in prokaryotes, which acts as a UDP-N-acetylglucosamine kinase.^[1] Its function is to inhibit cell wall biosynthesis and it may act as a bactericide in nature. It is also thought that Zeta toxin induces reversible protective dormancy and permeation to propidium iodide (PI).^[2]

Mechanism

This protein family entry consists of several bacterial zeta toxin proteins. Zeta toxin is thought to be part of a postsegregational killing (PSK) system involved in the killing of plasmid-free cells. 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.^[3]

Structure

The Zeta Toxin is folded like a phosphotransferase. This domain features an α/β structure and the central twisted β-sheet contains six β-strands. The first 5 strands are parallel but β-strand 6 is antiparallel and connected by a short loop to β-strand 5. α-Helices are inserted between and flank the β-strands.^[3]

Notes and References

1. A novel mechanism of programmed cell death in bacteria by toxin-antitoxin systems corrupts peptidoglycan synthesis . Mutschler, H., Gebhardt, M., Shoeman, R.L. and Meinhart, A. . PLOS Biol . 2011 . 9 . 3 .
   1. e1001033–e1001033
   . 21445328 . 10.1371/journal.pbio.1001033 . 3062530 . free .
2. Lioy VS, Machon C, Tabone M, Gonzalez-Pastor JE, Daugelavicius R, Ayora S, etal . The ζ toxin induces a set of protective responses and dormancy. . PLOS ONE . 2012 . 7 . 1 . e30282 . 22295078 . 10.1371/journal.pone.0030282 . 3266247 . 2012PLoSO...730282L . free .
3. Meinhart A, Alonso JC, Sträter N, Saenger W . Crystal structure of the plasmid maintenance system epsilon/zeta: functional mechanism of toxin zeta and inactivation by epsilon 2 zeta 2 complex formation . Proc. Natl. Acad. Sci. U.S.A. . 100 . 4 . 1661–6 . February 2003 . 12571357 . 149889 . 10.1073/pnas.0434325100 . free .