Mutants of the RNA-processing enzyme RNase E reverse the extreme slow-growth phenotype caused by a mutant translation factor EF-Tu.
Mol Microbiol
; 70(5): 1194-209, 2008 Dec.
Article
en En
| MEDLINE
| ID: mdl-18990188
ABSTRACT
Salmonella enterica with mutant EF-Tu (Gln125Arg) has a low level of EF-Tu, a reduced rate of protein synthesis and an extremely slow growth rate. Eighty independent suppressor mutations were selected that restored normal growth. In some cases (n= 7) suppression was due to mutations in tufA but, surprisingly, in most cases (n= 73) to mutations in rne, the gene coding for RNase E. These rne mutations alone had only modest effects on growth rate. Fifty different suppressor mutations were isolated in rne, all located in or close to the N-terminal endonucleolytic half of RNase E. Steady state levels of several mRNAs were lower in the mutant tuf strain but restored to wild-type levels in the tuf-rne double mutant. In contrast, the half-lives of mRNAs were unaffected by the tuf mutation. We propose a model where the tuf mutation causes the ribosome following RNA polymerase to pause, possibly in a codon-specific manner, exposing unshielded nascent message to RNase E cleavage. Normal growth rate can be restored by increasing EF-Tu activity or by reducing RNase E activity. Accordingly, RNase E is suggested to act at two distinct stages in the life of mRNA early, on the nascent transcript; late, on the complete mRNA.
Texto completo:
1
Bases de datos:
MEDLINE
Asunto principal:
Salmonella typhimurium
/
Proteínas Bacterianas
/
Factor Tu de Elongación Peptídica
/
Endorribonucleasas
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Mol Microbiol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
MICROBIOLOGIA
Año:
2008
Tipo del documento:
Article
País de afiliación:
Suecia