Stress Can Induce Transcription of Toxin-Antitoxin Systems without Activating Toxin.
Mol Cell
; 79(2): 280-292.e8, 2020 07 16.
Article
em En
| MEDLINE
| ID: mdl-32533919
ABSTRACT
Toxin-antitoxin (TA) systems are ubiquitous genetic elements in bacterial genomes, but their functions are controversial. Although they are frequently postulated to regulate cell growth following stress, few null phenotypes for TA systems have been reported. Here, we show that TA transcript levels can increase substantially in response to stress, but toxin is not liberated. We find that the growth of an Escherichia coli strain lacking ten TA systems encoding endoribonuclease toxins is not affected following exposure to six stresses that each trigger TA transcription. Additionally, using RNA sequencing, we find no evidence of mRNA cleavage following stress. Stress-induced transcription arises from antitoxin degradation and relief of transcriptional autoregulation. Importantly, although free antitoxin is readily degraded in vivo, antitoxin bound to toxin is protected from proteolysis, preventing release of active toxin. Thus, transcription is not a reliable marker of TA activity, and TA systems do not strongly promote survival following individual stresses.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Estresse Fisiológico
/
Toxinas Bacterianas
/
Transcrição Gênica
/
Regulação Bacteriana da Expressão Gênica
/
Proteínas de Escherichia coli
/
Escherichia coli
/
Sistemas Toxina-Antitoxina
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article