The SRP9/14 subunit of the human signal recognition particle binds to a variety of Alu-like RNAs and with higher affinity than its mouse homolog.
The heterodimeric subunit, SRP9/14, of the signal recognition particle (SRP) has previously been found to bind to scAlu and scB1 RNAs in vitro and to exist in large excess over SRP in anthropoid cells. Here we show that human and mouse SRP9/14 bind with high affinities to other Alu-like RNAs of different evolutionary ages including the neuron-specific BC200 RNA. The relative dissociation constants of the different RNA-protein complexes are inversely proportional to the evolutionary distance between the Alu RNA species and 7SL RNA. In addition, the human SRP9/14 binds with higher affinity than mouse SRP9/14 to all RNAs analyzed and this difference is not explained by the additional C-terminal domain present in the anthropoid SRP14. The conservation of high affinity interactions between SRP9/14 and Alu-like RNAs strongly indicates that these Alu-like RNPs exist in vivo and that they have cellular functions. The observation that human SRP9/14 binds better than its mouse counterpart to distantly related Alu RNAs, such as recently transposed elements, suggests that the anthropoid-specific excess of SRP9/14 may have a role in controlling Alu amplification rather than in compensating a defect in SRP assembly and functions.
Bovia
F
F
Département de Biologie Cellulaire, Université de Genève, Sciences III, CH-1211 Geneva 4, Switzerland.
Wolff
N
N
Ryser
S
S
Strub
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D003001:Cloning, Molecular; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D019143:Evolution, Molecular; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D020733:RNA, Small Cytoplasmic; D016601:RNA-Binding Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D018271:Signal Recognition Particle / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics
D020733:RNA, Small Cytoplasmic; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; C490326:SRP14 protein, human; D018271:Signal Recognition Particle; C490325:Srp14 protein, mouse; C503637:Srp72 protein, mouse; D012313:RNA