Protein Family Models

SsrA-binding protein SmpB, together with SsrA RNA, mediates trans-translation in prokaryotes for translational surveillance and ribosome rescue

Date:

2023-06-01

Binds to ssrA RNA (tmRNA) and is required for its successful binding to ribosomes; also appears to function in the trans-translation step by promoting accommodation of tmRNA into the ribosomal A site; both the tmRNA and SmpB are regulated in cell cycle-dependent manner; functions in release of stalled ribosomes from damaged mRNAs and targeting proteins for degradation

Gene:

smpB

Date:

2021-07-22

This model describes the SsrA-binding protein, also called tmRNA binding protein, small protein B, and SmpB. The small, stable RNA SsrA (also called tmRNA or 10Sa RNA) recognizes stalled ribosomes such as occur during translation from message that lacks a stop codon. It becomes charged with Ala like a tRNA, then acts as mRNA to resume translation started with the defective mRNA. The short C-terminal peptide tag added by the SsrA system marks the abortively translated protein for degradation. SmpB binds SsrA after its aminoacylation but before the coupling of the Ala to the nascent polypeptide chain and is an essential part of the SsrA peptide tagging system. SmpB has been associated with the survival of bacterial pathogens in conditions of stress. It is universal in the first 100 sequenced bacterial genomes.

Gene:

smpB

Date:

2021-04-27