RESEARCH HIGHLIGHTS - RelEB3 toxin–antitoxin system of Salmonella Typhimurium

by Tengku Yasmin Yusof, Eugene Boon Beng Ong, Aik-Hong Teh

Bacteria contain toxin–antitoxin (TA) systems that help them manage stress. A toxin inhibits essential cellular pathways such as protein translation during stress, leading to rapid growth arrest and the formation of persister cells. The RelEB3 TA system of Salmonella Typhimurium consists of a RelE3 toxin which suppresses bacterial growth by degrading free RNA independently of the ribosome. Unlike typical antitoxins, however, the RelB3 antitoxin does not neutralise the toxin, although it does bind to a palindromic motif in the TA operon's promoter site to regulate their transcription. Nevertheless, RelB3 was found to contain a unique Pro14 which is conserved as Ala in most homologues, and mutating Pro14 to Ala enabled the antitoxin to bind to RelE3 and restored bacterial growth. The P14 RelB3 variant, which likely arose by a point mutation in a recent ancestor of S. Typhimurium and closely related serovars, could have possibly provided the bacteria with a faster response to stress.

Link:  https://www.sciencedirect.com/science/article/pii/S0141813022018475


CCB Ref.:  2022_RH_tah_02
Date :  16/12/2022