Phylogenetic analysis of tmRNA genes within a bacterial subgroup reveals a specific structural signature.
Bacterial tmRNA mediates a trans-translation reaction, which permits the recycling of stalled ribosomes and probably also contributes to the regulated expression of a subset of genes. Its action results in the addition of a small number of C-terminal amino acids to protein whose synthesis had stalled and these constitute a proteolytic recognition tag for the degradation of these incompletely synthesized proteins. Previous work has identified pseudoknots and stem-loops that are widely conserved in divergent bacteria. In the present work an alignment of tmRNA gene sequences within 13 beta-proteobacteria reveals an additional sub-structure specific for this bacterial group. This sub-structure is in pseudoknot Pk2, and consists of one to two additional stem-loop(s) capped by stable GNRA tetraloop(s). Three-dimensional models of tmRNA pseudoknot 2 (Pk2) containing various topological versions of the additional sub-structure suggest that the sub-structures likely point away from the core of the RNA, containing both the tRNA and the mRNA domains. A putative tertiary interaction has also been identified.
Department of Human Genetics, University of Utah, 15N 2030E Room 6250, Salt Lake City, UT 84112-5330, USA. bfelden@univrennes1.fr
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B
Felden
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Massire
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Westhof
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Atkins
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Gesteland
D001483:Base Sequence; D020562:Betaproteobacteria / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; C096222:tmRNA; D012343:RNA, Transfer