Inhibitory mechanism of Escherichia coli RelE-RelB toxin-antitoxin module involves a helix displacement near an mRNA interferase active site.

ABSTRACT: In Escherichia coli, RelE toxin participates in growth arrest and cell death by inducing mRNA degradation at the ribosomal A-site under stress conditions. The NMR structures of a mutant of E. coli RelE toxin, RelE(R81A/R83A), with reduced toxicity and its complex with an inhibitory peptide from RelB antitoxin, RelB(C) (Lys(47)-Leu(79)), have been determined. In the free RelE(R81A/R83A) structure, helix alpha4 at the C terminus adopts a closed conformation contacting with the beta-sheet core and adjacent loops. In the RelE(R81A/R83A)-RelB(C) complex, helix alpha3(*) of RelB(C) displaces alpha4 of RelE(R81A/R83A) from the binding site on the beta-sheet core. This helix replacement results in neutralization of a conserved positively charged cluster of RelE by acidic residues from alpha3(*) of

SUBMITTER: Li GY 

PROVIDER: S-EPMC2682910 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature