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Discovery of a novel type IIb RelBE toxin‐antitoxin system in Mycobacterium tuberculosis defined by co‐regulation with an antisense RNA
Author(s) -
Dawson Clinton C.,
Cummings Jason E.,
Starkey Julie M.,
Slayden Richard A.
Publication year - 2022
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14917
Subject(s) - biology , antitoxin , rnase p , mycobacterium tuberculosis , antisense rna , rna , transcription (linguistics) , microbiology and biotechnology , toxin , genetics , gene , tuberculosis , medicine , linguistics , philosophy , pathology
Toxin‐antitoxin loci regulate adaptive responses to stresses associated with the host environment and drug exposure. Phylogenomic studies have shown that Mycobacterium tuberculosis encodes a naturally expanded type II toxin‐antitoxin system, including ParDE/RelBE superfamily members. Type II toxins are presumably regulated exclusively through protein–protein interactions with type II antitoxins. However, experimental observations in M. tuberculosis indicated that additional control mechanisms regulate RelBE2 type II loci under host‐associated stress conditions. Herein, we describe for the first time a novel antisense RNA, termed asRelE2, that co‐regulates RelE2 production via targeted processing by the Mtb RNase III, Rnc. We find that convergent expression of this coding‐antisense hybrid TA locus, relBE2‐asrelE2 , is controlled in a cAMP‐dependent manner by the essential cAMP receptor protein transcription factor, Crp, in response to the host‐associated stresses of low pH and nutrient limitation. Ex vivo survival studies with relE2 and asrelE2 knockout strains showed that RelE2 contributes to Mtb survival in activated macrophages and low pH to nutrient limitation. To our knowledge, this is the first report of a novel tripartite type IIb TA loci and antisense post‐transcriptional regulation of a type II TA loci.