title: Archease from Pyrococcus abyssi improves substrate specificity and solubility of a tRNA m5C methyltransferase.
abstract: Members of the archease superfamily of proteins are represented in all three domains of life. Archease genes are generally located adjacent to genes encoding proteins involved in DNA or RNA processing. Archease have therefore been predicted to play a modulator or chaperone role in selected steps of DNA or RNA metabolism, although the roles of archeases remain to be established experimentally. Here we report the function of one of these archeases from the hyperthermophile Pyrococcus abyssi. The corresponding gene (PAB1946) is located in a bicistronic operon immediately upstream from a second open reading frame (PAB1947), which is shown here to encode a tRNA m(5)C methyltransferase. In vitro, the purified recombinant methyltransferase catalyzes m(5)C formation at several cytosines within tRNAs with preference for C49. The specificity of the methyltransferase is increased by the archease. In solution, the archease exists as a monomer, trimer, and hexamer. Only the oligomeric states bind the methyltransferase and prevent its aggregation, in addition to hindering dimerization of the methyltransferase-tRNA complex. This P. abyssi system possibly reflects the general function of archeases in preventing protein aggregation and modulating the function of their accompanying proteins.
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France. Sylvie.Auxilien@lebs.cnrs-gif.fr
authors.forename: Sylvie
authors.initials: S
authors.lastname: Auxilien
authors.forename: Fatima
authors.initials: F
authors.lastname: El Khadali
authors.forename: Anette
authors.initials: A
authors.lastname: Rasmussen
authors.forename: Stephen
authors.initials: S
authors.lastname: Douthwaite
authors.forename: Henri
authors.initials: H
authors.lastname: Grosjean
mesh_terms: D003001:Cloning, Molecular; D003596:Cytosine / Q000378:metabolism; D008745:Methylation; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D011066:Poly C / Q000378:metabolism; D043903:Pyrococcus abyssi / Q000201:enzymology* / Q000235:genetics*; D019642:RNA, Archaeal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012995:Solubility; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013379:Substrate Specificity; D012359:tRNA Methyltransferases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D019642:RNA, Archaeal; D011066:Poly C; D003596:Cytosine; D012359:tRNA Methyltransferases