The 5S rRNA maturase, ribonuclease M5, is a Toprim domain family member.
The maturation of 5S ribosomal RNA in low G+C Gram-positive bacteria is catalyzed by a highly conserved, approximately 190 residue, enzyme, called ribonuclease M5 (RNase M5). Sequence alignment had predicted that the N-terminal half of RNase M5 would consist of a Toprim domain, a protein fold found in type IA and type II topoisomerases, DnaG-like primases, OLD family nucleases and RecR proteins [L. Aravind, D. D. Leipe and E. V. Koonin (1998) Nucleic Acids Res., 26, 4205-4213]. Here, we present structural modelling data and a mutational analysis of RNase M5 that confirms this hypothesis. The N-terminal half of RNase M5 can be fitted to the Toprim domain of the DnaG catalytic core. Mutation of amino acid residues highly conserved among RNase M5 enzymes and members of the Toprim domain family showed that alteration of residues critical for topoisomerase and primase activity also had a dramatic effect on the cleavage of 5S rRNA precursor by RNase M5 both in vivo and in vitro. This suggests that the mechanisms of double-stranded RNA cleavage by RNase M5 and double-stranded DNA cleavage by members of the topoisomerase family are related.
Allemand
Frédéric
F
UPR 9073, Université de Paris 7-Denis Diderot, Institut de Biologie Physico-Chimique 13 rue Pierre et Marie Curie, 75005 Paris, France.
Mathy
Nathalie
N
Brechemier-Baey
Dominique
D
Condon
Ciarán
C
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology*; D019915:DNA Primase / Q000737:chemistry; D026942:DNA Topoisomerases / Q000737:chemistry; D004722:Endoribonucleases / Q000737:chemistry* / Q000145:classification* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary; D012341:RNA, Ribosomal, 5S / Q000378:metabolism*; D016415:Sequence Alignment; D014357:Trypsin / Q000378:metabolism
D000596:Amino Acids; D012341:RNA, Ribosomal, 5S; D019915:DNA Primase; D004722:Endoribonucleases; C027761:ribonuclease M5; D014357:Trypsin; D026942:DNA Topoisomerases