Induced ectopic expression of HigB toxin in Mycobacterium tuberculosis results in growth inhibition, reduced abundance of a subset of mRNAs and cleavage of tmRNA.
In Mycobacterium tuberculosis, the genes Rv1954A-Rv1957 form an operon that includes Rv1955 and Rv1956 which encode the HigB toxin and the HigA antitoxin respectively. We are interested in the role and regulation of this operon, since toxin-antitoxin systems have been suggested to play a part in the formation of persister cells in mycobacteria. To investigate the function of the higBA locus, effects of toxin expression on mycobacterial growth and transcript levels were assessed in M. tuberculosis H37Rv wild type and in an operon deletion background. We show that expression of HigB toxin in the absence of HigA antitoxin arrests growth and causes cell death in M. tuberculosis. We demonstrate HigB expression to reduce the abundance of IdeR and Zur regulated mRNAs and to cleave tmRNA in M. tuberculosis, Escherichia coli and Mycobacterium smegmatis. This study provides the first identification of possible target transcripts of HigB in M. tuberculosis.
Division of Mycobacterial Research, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.
Dorothée L
DL
Schuessler
Teresa
T
Cortes
Amanda S
AS
Fivian-Hughes
Kathryn E A
KE
Lougheed
Evelyn
E
Harvey
Roger S
RS
Buxton
Elaine O
EO
Davis
Douglas B
DB
Young
D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D015870:Gene Expression; D050296:Microbial Viability; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000254:growth & development; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development*; D020871:RNA Stability; D012329:RNA, Bacterial / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism
D001427:Bacterial Toxins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012097:Repressor Proteins; C096222:tmRNA