title: RNA-mediated interaction between the peptide-binding and GTPase domains of the signal recognition particle.
abstract: The signal recognition particle (SRP) targets nascent proteins to cellular membranes for insertion or secretion by recognizing polypeptides containing an N-terminal signal sequence as they emerge from the ribosome. GTP-dependent binding of SRP to its receptor protein leads to controlled release of the nascent chain into a membrane-spanning translocon pore. Here we show that the association of the SRP with its receptor triggers a marked conformational change in the complex, localizing the SRP RNA and the adjacent signal peptide-binding site at the SRP-receptor heterodimer interface. The orientation of the RNA suggests how peptide binding and GTP hydrolysis can be coupled through direct structural contact during cycles of SRP-directed protein translocation.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, California 94705, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Spanggord
authors.forename: Fai
authors.initials: F
authors.lastname: Siu
authors.forename: Ailong
authors.initials: A
authors.lastname: Ke
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Doudna
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D019281:Dimerization; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D010455:Peptides / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial; D012335:RNA, Ribosomal / Q000737:chemistry* / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism; D018000:Receptors, Peptide / Q000737:chemistry* / Q000378:metabolism; D018271:Signal Recognition Particle / Q000737:chemistry* / Q000378:metabolism
chemical_list: C409968:4.5S RNA; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C082931:Ffh protein, E coli; C087406:FtsY protein, Bacteria; D010455:Peptides; D012329:RNA, Bacterial; D012335:RNA, Ribosomal; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D018271:Signal Recognition Particle; C036318:signal peptide receptor; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases