Nucleic Acids Research Advance Access published online on October 25, 2007
Nucleic Acids Research, doi:10.1093/nar/gkm898
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Molecular Biology |
Domain I of ribosomal protein L1 is sufficient for specific RNA binding
1Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow region, Russia, 2Biocenter, Division of Medical Biochemistry, Innsbruck Medical University, Fritz-Pregl-Str. 3, 6020 Innsbruck, Austria, 3Angiogenesis Laboratory, Ludwig Institute for Cancer Research, PO Box 2008, Royal Melbourne Hospital, Parkville, VIC 3050 and 4CSIRO Molecular & Health Technologies 343 Royal Parade Parkville VIC 3052, Australia
* To whom correspondence should be addressed. Tel: +43 512 9003-70331; Fax: +43 512 9003-73110; Email: wolfgang.piendl{at}i-med.ac.at
Received August 9, 2007. Revised October 4, 2007. Accepted October 4, 2007.
Ribosomal protein L1 has a dual function as a ribosomal protein binding 23S rRNA and as a translational repressor binding its mRNA. L1 is a two-domain protein with N- and C-termini located in domain I. Earlier it was shown that L1 interacts with the same targets on both rRNA and mRNA mainly through domain I. We have suggested that domain I is necessary and sufficient for specific RNA-binding by L1. To test this hypothesis, a truncation mutant of L1 from Thermus thermophilus, representing domain I, was constructed by deletion of the central part of the L1 sequence, which corresponds to domain II. It was shown that the isolated domain I forms stable complexes with specific fragments of both rRNA and mRNA. The crystal structure of the isolated domain I was determined and compared with the structure of this domain within the intact protein L1. This comparison revealed a close similarity of both structures. Our results confirm our suggestion that in protein L1 its domain I alone is sufficient for specific RNA binding, whereas domain II stabilizes the L1-rRNA complex.