Ribosomal protein L7a binds RNA through two distinct RNA-binding domains.
The human ribosomal protein L7a is a component of the major ribosomal subunit. We previously identified three nuclear-localization-competent domains within L7a, and demonstrated that the domain defined by aa (amino acids) 52-100 is necessary, although not sufficient, to target the L7a protein to the nucleoli. We now demonstrate that L7a interacts in vitro with a presumably G-rich RNA structure, which has yet to be defined. We also demonstrate that the L7a protein contains two RNA-binding domains: one encompassing aa 52-100 (RNAB1) and the other encompassing aa 101-161 (RNAB2). RNAB1 does not contain any known nucleic-acid-binding motif, and may thus represent a new class of such motifs. On the other hand, a specific region of RNAB2 is highly conserved in several other protein components of the ribonucleoprotein complex. We have investigated the topology of the L7a-RNA complex using a recombinant form of the protein domain that encompasses residues 101-161 and a 30mer poly(G) oligonucleotide. Limited proteolysis and cross-linking experiments, and mass spectral analyses of the recombinant protein domain and its complex with poly(G) revealed the RNA-binding region.
Russo
Giulia
G
Dipartimento di Biochimica e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5 Napoli, I-80131 Italy.
Cuccurese
Monica
M
Monti
Gianluca
G
Russo
Annapina
A
Amoresano
Angela
A
Pucci
Pietro
P
Pietropaolo
Concetta
C
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017124:Conserved Sequence; D003432:Cross-Linking Reagents; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012342:RNA, Small Nuclear / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000378:metabolism*; D013379:Substrate Specificity; D014357:Trypsin / Q000378:metabolism
D003432:Cross-Linking Reagents; D012342:RNA, Small Nuclear; D016601:RNA-Binding Proteins; C057838:RPL7A protein, human; D012269:Ribosomal Proteins; C405482:U4 small nuclear RNA; D012313:RNA; D014357:Trypsin