Transcriptional analysis of the gene encoding peptidyl-tRNA hydrolase in Escherichia coli.
Gene pth encodes peptidyl-tRNA hydrolase (Pth), an enzyme that cleaves peptidyl-tRNAs released abortively from ribosomes during protein synthesis. In the Escherichia coli chromosome, pth is flanked by ychH and ychF, two genes of unknown function. Pth is essential for cell viability, especially under conditions leading to overproduction of peptidyl-tRNA. In an attempt to unveil the elements that affect pth expression, the transcriptional features of the pth region were investigated. Northern blot experiments showed that both pth and ychF, the 3'-proximal gene, are cotranscribed in a bicistronic transcript. However, transcripts containing each of the individual messages were also detected. Accordingly, two transcriptional promoters were identified by primer extension experiments: one located upstream of pth, which presumably gives rise to both the mono and bicistronic pth transcripts, and the other, preceding ychF, which generates its monocistronic message. Deletion analysis indicates that pth transcript stability depends on ychF integrity. Also, a defect in RNase E activity resulted in Pth overproduction. It is proposed that RNase E processing within ychF in the bicistronic message limits pth expression.
Cruz-Vera
L Rogelio
LR
Departamento de Genética y Biologı́a Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, México DF 07000, Mexico1.
Galindo
José Manuel
JM
Departamento de Genética y Biologı́a Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, México DF 07000, Mexico1.
Guarneros
Gabriel
G
Departamento de Genética y Biologı́a Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, México DF 07000, Mexico1.
D001483:Base Sequence; D015152:Blotting, Northern; D002265:Carboxylic Ester Hydrolases / Q000096:biosynthesis / Q000235:genetics*; D004269:DNA, Bacterial / Q000032:analysis; D004722:Endoribonucleases / Q000378:metabolism / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D020871:RNA Stability; D012329:RNA, Bacterial / Q000032:analysis; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D012329:RNA, Bacterial; D004722:Endoribonucleases; D002265:Carboxylic Ester Hydrolases; C019674:aminoacyl-tRNA hydrolase; C022537:ribonuclease E