The FtsJ/RrmJ heat shock protein of Escherichia coli is a 23 S ribosomal RNA methyltransferase.
Ribosomal RNAs undergo several nucleotide modifications including methylation. We identify FtsJ, the first encoded protein of the ftsJ-hflB heat shock operon, as an Escherichia coli methyltransferase of the 23 S rRNA. The methylation reaction requires S-adenosylmethionine as donor of methyl groups, purified FtsJ or a S(150) supernatant from an FtsJ-producing strain, and ribosomes from an FtsJ-deficient strain. In vitro, FtsJ does not efficiently methylate ribosomes purified from a strain producing FtsJ, suggesting that these ribosomes are already methylated in vivo by FtsJ. FtsJ is active on ribosomes and on the 50 S ribosomal subunit, but is inactive on free rRNA, suggesting that its natural substrate is ribosomes or a pre-ribosomal ribonucleoprotein particle. We identified the methylated nucleotide as 2'-O-methyluridine 2552, by reverse phase high performance liquid chromatography analysis, boronate affinity chromatography, and hybridization-protection experiments. In view of its newly established function, FtsJ is renamed RrmJ and its encoding gene, rrmJ.
Caldas
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Biochimie Génétique, Institut Jacques Monod, Université Paris 7, 2, place Jussieu, 75005 Paris, France.
Binet
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Bouloc
P
P
Costa
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Desgres
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J
Richarme
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G
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D017931:DNA Primers; D004926:Escherichia coli / Q000378:metabolism*; D008780:Methyltransferases / Q000737:chemistry / Q000378:metabolism*
D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D017931:DNA Primers; D008780:Methyltransferases; C102247:rlmE protein, E coli; C035181:rRNA (adenosine-O-2'-)methyltransferase