Suppression by enhanced RpoE activity of the temperature-sensitive phenotype of a degP ssrA double mutant in Escherichia coli

• Published in: Genes & Genetic Systems Vol. 84; no. 1; pp. 15 - 24
• Main Authors: Ono, K.(Okayama Univ. (Japan)), Kutsukake, K, Abo, T
• Format: Journal Article
• Language: English
• Published: Japan The Genetics Society of Japan 2009; Japan Science and Technology Agency
• Subjects: Amino Acid Substitution; ARN MENSAJERO; ARN MESSAGER; DegP; ESCHERICHIA COLI; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; EXPRESION GENICA; EXPRESSION DES GENES; GENE EXPRESSION; GENETIC DISORDERS; HEAT TOLERANCE; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Hot Temperature; MESSENGER RNA; MUTACION; MUTANT; MUTANTES; MUTANTS; MUTATION; Mutation, Missense; NUCLEOTIDE SEQUENCE; Periplasmic Proteins - genetics; Periplasmic Proteins - metabolism; Phenotype; RNA, Bacterial - genetics; RNA, Bacterial - metabolism; RpoE; SECUENCIA NUCLEOTIDICA; SEQUENCE NUCLEOTIDIQUE; Serine Endopeptidases - genetics; Serine Endopeptidases - metabolism; Sigma Factor - genetics; Sigma Factor - metabolism; SsrA; Stress, Physiological - physiology; TEMPERATURA; TEMPERATURE; TOLERANCE A LA CHALEUR; TOLERANCIA AL CALOR; trans-translation; TRASTORNOS GENETICOS; TROUBLE GENETIQUE
• ISSN: 1341-7568; 1880-5779
• DOI: 10.1266/ggs.84.15

SsrA is a small RNA playing a crucial role in trans-translation, which leads to rescue of stalled ribosomes on or at the end of mRNA and addition of the degradation tag to a growing polypeptide. The lack of SsrA has been shown to enhance the temperature-sensitive (ts) phenotype of an E. coli strain defective in the degP gene, which encodes one of the periplasmic proteases. This severe ts phenotype was relieved only partially by an SsrADD variant, which can lead to ribosome rescue but adds a protease-resistant tag instead of the degradation tag, suggesting that accumulation of polypeptides programmed by truncated mRNAs is responsible for growth defect of the ssrA degP mutant. Expression of an S210A-mutant DegP protein, which lacks the protease activity but retains the chaperone activity, could relieve the ts phenotype of the double mutant, suggesting that the chaperone activity but not the protease activity of DegP is required for growth of the ssrA-deficient cells at high temperature. Overexpression of the rpoE gene, which encodes σE responsible for the expression of factors involved in extracellular stress response, also suppressed the ts phenotype of the ssrA degP mutant. This suggests that the stress-responsing pathway(s) may be involved in the enhancement of ts phenotype of degP mutant in the absence of SsrA.