Nucleic Acids Research Advance Access published online on June 22, 2007
Nucleic Acids Research, doi:10.1093/nar/gkm462
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Nucleic Acid Enzymes |
YtqI from Bacillus subtilis has both oligoribonuclease and pAp-phosphatase activity
1Institut Pasteur, URA 2171, Unité de Génétique des Génomes Bactériens, 75724 Paris Cedex 15 and 2Institut Gustave Roussy, UMR 8126, Unité Interactions Moléculaires et Cancer, 94805 Villejuif, France
*To whom correspondence should be addressed. Tel: 33 140613870; Fax: 33 145688948; Email: umechold{at}pasteur.fr
Received April 2, 2007. Revised May 25, 2007. Accepted May 25, 2007.
Oligoribonuclease is the only RNase in Escherichia coli that is able to degrade RNA oligonucleotides five residues and shorter in length. Firmicutes including Bacillus subtilis do not have an Oligoribonuclease (Orn) homologous protein and it is not yet understood which proteins accomplish the equivalent function in these organisms. We had previously identified oligoribonucleases Orn from E. coli and its human homolog Sfn in a screen for proteins that are regulated by 3'-phosphoadenosine 5'-phosphate (pAp). Here, we identify YtqI as a potential functional analog of Orn through its interaction with pAp. YtqI degrades RNA oligonucleotides in vitro with preference for 3-mers. In addition, YtqI has pAp-phosphatase activity in vitro. In agreement with these data, YtqI is able to complement both orn and cysQ mutants in E. coli. An ytqI mutant in B. subtilis shows impairment of growth in the absence of cysteine, a phenotype resembling that of a cysQ mutant in E. coli. Phylogenetic distribution of YtqI, Orn and CysQ supports bifunctionality of YtqI.