title: Conservation of RNA chaperone activity of the human La-related proteins 4, 6 and 7.
abstract: The La module is a conserved tandem arrangement of a La motif and RNA recognition motif whose function has been best characterized in genuine La proteins. The best-characterized substrates of La proteins are pre-tRNAs, and previous work using tRNA mediated suppression in Schizosaccharomyces pombe has demonstrated that yeast and human La enhance the maturation of these using two distinguishable activities: UUU-3'OH-dependent trailer binding/protection and a UUU-3'OH independent activity related to RNA chaperone function. The La module has also been identified in several conserved families of La-related proteins (LARPs) that engage other RNAs, but their mode of RNA binding and function(s) are not well understood. We demonstrate that the La modules of the human LARPs 4, 6 and 7 are also active in tRNA-mediated suppression, even in the absence of stable UUU-3'OH trailer protection. Rather, the capacity of these to enhance pre-tRNA maturation is associated with RNA chaperone function, which we demonstrate to be a conserved activity for each hLARP in vitro. Our work reveals insight into the mechanisms by which La module containing proteins discriminate RNA targets and demonstrates that RNA chaperone activity is a conserved function across representative members of the La motif-containing superfamily.
authors.affiliation: Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada.
authors.forename: Rawaa H
authors.initials: RH
authors.lastname: Hussain
authors.forename: Mariam
authors.initials: M
authors.lastname: Zawawi
authors.forename: Mark A
authors.initials: MA
authors.lastname: Bayfield
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001324:Autoantigens / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D012322:RNA Precursors / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000737:chemistry / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism; D016415:Sequence Alignment; D000097585:SS-B Antigen
chemical_list: D001324:Autoantigens; D012322:RNA Precursors; D012343:RNA, Transfer; D012261:Ribonucleoproteins; D000097585:SS-B Antigen; C528908:Larp7 protein, human