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Glutamine‐rich toxic proteins GrtA, GrtB and GrtC together with the antisense RNA AsgR constitute a toxin–antitoxin‐like system in Corynebacterium glutamicum
Author(s) -
Maeda Tomoya,
Tanaka Yuya,
Inui Masayuki
Publication year - 2018
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.13951
Subject(s) - corynebacterium glutamicum , biology , antisense rna , transcription (linguistics) , rnase p , microbiology and biotechnology , ribonuclease iii , rna , untranslated region , gene , antitoxin , gene expression , toxin , biochemistry , rna interference , linguistics , philosophy
Summary The Corynebacterium glutamicum R grtA (cgR_2936), grtB (cgR_2934) and grtC (cgR_2933) genes were identified as paralogs encoding glutamine‐rich toxic proteins. We also identified a new antisense small RNA AsgR (antisense sRNA for grtA ) that overlaps the 3′ end of the grtA gene. Single over‐expressions of grtA , grtB and grtC resulted in complete inhibition of Escherichia coli cell growth. This growth was rescued by co‐expression of AsgR. Similar effects were observed in C. glutamicum , although the toxicities of these proteins were moderate. Inhibition of AsgR transcription resulted in increased levels and prolonged half‐lives of grtA , grtB and grtC mRNAs. We also found that the expression levels of grtA , grtB and grtC were increased in an RNase III deletion mutant. Primer extension analysis revealed the RNase III cleavage site to be in the 3′ untranslated region (3′‐UTR) of the grtA mRNA. The expression levels of grtA , grtB and grtC were increased after exposure to several stresses, including heat shock, treatment with penicillin G, lysozyme or H 2 O 2 . The deletions of grtABC and asgR genes resulted in decreased survival rate under several stresses. These results indicate that GrtABC and AsgR constitute a type I toxin–antitoxin‐like system in C. glutamicum .