1gvn: Difference between revisions

[[Image:1gvn.jpg|left|200px]]

'''CRYSTAL STRUCTURE OF THE PLASMID MAINTENANCE SYSTEM EPSILON/ZETA: MEACHNISM OF TOXIN INACTIVATION AND TOXIN FUNCTION'''

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.

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 18:04:00 2008''