Affiliation:
1. Department of Genetics, University of Georgia, Athens, Georgia, USA
2. Department of Microbiology University of Georgia, Athens, Georgia, USA
Abstract
ABSTRACT
RNase PH, encoded by the
rph
gene, is a 3′→5′ exoribonuclease that in
E. coli
participates primarily in the 3′ maturation of pre-tRNAs and the degradation of rRNA in stationary-phase cells. Interestingly, the routinely used laboratory strains of MG1655 and W3110 have naturally acquired the
rph-1
allele, encoding a truncated catalytically inactive RNase PH protein which is widely assumed to be benign. Contrary to this assumption, we show that the
rph-1
-encoded Rph-1 protein inhibits RNase P-mediated 5′-end maturation of primary pre-tRNAs with leaders of <5 nucleotides in the absence of RppH, an RNA pyrophosphohydrolase. In contrast, RppH is not required for 5′-end maturation of endonucleolytically generated pre-tRNAs in the
rph-1
strain and for any tRNAs in Δ
rph
mutant or
rph
+
strains. We propose that the Rph-1 protein bound to the 3′ end of the substrate creates a steric hindrance that in the presence of a triphosphate at the 5′ end reduces the ability of RNase P to bind to the pre-tRNA.
IMPORTANCE
In this paper, we demonstrate that the
rph-1
mutation found in commonly used
E. coli
strains leads to the synthesis of a truncated functionally inactive RNase PH protein that interferes with the 5′-end maturation of specific tRNAs with short 5′ leaders by RNase P in the absence of RppH, an RNA pyrophosphohydrolase that converts primary 5′ triphosphates into 5′ monophosphates. The data presented indicate that the presence of the triphosphate interferes with RNase P binding to the pre-tRNA.
Funder
HHS | National Institutes of Health
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
7 articles.
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