4dmg

Publication Abstract from PubMed

Methylation of cytidines at carbon-5 is a com-mon posttranscriptional RNA modification encountered across all domains of life. Here, we characterize the modifications of C1942 and C1962 in Thermus thermophilus 23S rRNA as 5-methylcytidines (m5C) and identify the two associated methyltransferases. The methyltransferase modifying C1942, named RlmO, has not been characterized previously. RlmO modifies naked 23S rRNA, but not the assembled 50S subunit or 70S ribosomes. The X-ray crystal structure of this enzyme in complex with the S-adenosyl-L-methionine cofactor at 1.7 A resolution confirms that RlmO is structurally related to other m5C rRNA methyltransferases. Key residues in the active site are located similar to the further distant 5-methyluridine methyltransferase RlmD, suggestive of a similar enzymatic mechanism. RlmO homologues are primarily found in mesophilic bacteria related to Thermus thermophilus. In accordance, we find that growth of the T. thermophilus strain with an inactivated C1942-methyltransferase gene is not compromised at non-optimal temperatures.

Identification and characterization of the Thermus thermophilus m5C methyltransferase modifying 23S rRNA base C1942.,Larsen LH, Rasmussen A, Giessing AM, Jogl G, Kirpekar F J Biol Chem. 2012 Jun 18. PMID:22711535^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.