Nucleic Acids Research Advance Access originally published online on May 21, 2007
Nucleic Acids Research 2007 35(11):3752-3763; doi:10.1093/nar/gkm318
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Nucleic Acids Research, 2007, Vol. 35, No. 11 3752-3763
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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RNA chaperone activity of L1 ribosomal proteins: phylogenetic conservation and splicing inhibition
1Max F. Perutz Laboratories, Department of Biochemistry, University of Vienna, Dr Bohrgasse 9/5, A-1030 Vienna, Austria, 2Biocenter, Division of Medical Biochemistry, Innsbruck Medical University, Fritz-Pregl-Str. 3, A-6020 Innsbruck, Austria and 3Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia
*To whom correspondence should be addressed. Tel: +43-1-4277-54694; Fax: +43-1-4277-9522; Email: katharina.semrad{at}univie.ac.at
Received October 3, 2006. Revised April 16, 2007. Accepted April 16, 2007.
RNA chaperone activity is defined as the ability of proteins to either prevent RNA from misfolding or to open up misfolded RNA conformations. One-third of all large ribosomal subunit proteins from E. coli display this activity, with L1 exhibiting one of the highest activities. Here, we demonstrate via the use of in vitro trans- and cis-splicing assays that the RNA chaperone activity of L1 is conserved in all three domains of life. However, thermophilic archaeal L1 proteins do not display RNA chaperone activity under the experimental conditions tested here. Furthermore, L1 does not exhibit RNA chaperone activity when in complexes with its cognate rRNA or mRNA substrates. The evolutionary conservation of the RNA chaperone activity among L1 proteins suggests a functional requirement during ribosome assembly, at least in bacteria, mesophilic archaea and eukarya. Surprisingly, rather than facilitating catalysis, the thermophilic archaeal L1 protein from Methanococcus jannaschii (MjaL1) completely inhibits splicing of the group I thymidylate synthase intron from phage T4. Mutational analysis of MjaL1 excludes the possibility that the inhibitory effect is due to stronger RNA binding. To our knowledge, MjaL1 is the first example of a protein that inhibits group I intron splicing.