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| Subject Categories: RNA | Proteins |
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| The EMBO Journal
(2008) 27, 840–851, doi:10.1038/emboj.2008.20 Published online 21 February 2008 |
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| Role of 16S ribosomal RNA methylations in translation initiation in Escherichia coli |
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| Gautam Das, Dinesh Kumar Thotala, Suman Kapoor, Sheelarani Karunanithi, Suman S Thakur1, N Sadananda Singh and Umesh Varshney |
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Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, Karnataka, India To whom correspondence should be addressed Umesh Varshney, Department of Microbiology and Cell Biology, Indian Institute of Science, CNR Rao Circle, Bangalore, Karnataka 560012, India. Tel.: +91 80 2293 2686; Fax: +91 80 2360 2697; E-mail: varshney@mcbl.iisc.ernet.in 1 Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India Received 16 August 2007; Accepted 18 January 2008; Published online 21 February 2008. |
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| Abstract |
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| Translation initiation from the ribosomal P-site is the specialty of the initiator tRNAs (tRNAfMet). Presence of the three consecutive G-C base pairs (G29-C41, G30-C40 and G31-C39) in their anticodon stems, a highly conserved feature of the initiator tRNAs across the three kingdoms of life, has been implicated in their preferential binding to the P-site. How this feature is exploited by ribosomes has remained unclear. Using a genetic screen, we have isolated an Escherichia coli strain, carrying a G122D mutation in folD, which allows initiation with the tRNAfMet containing mutations in one, two or all the three G-C base pairs. The strain shows a severe deficiency of methionine and S-adenosylmethionine, and lacks nucleoside methylations in rRNA. Targeted mutations in the methyltransferase genes have revealed a connection between the rRNA modifications and the fundamental process of the initiator tRNA selection by the ribosome. |
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| Keywords: S-adenosyl-L-methionine, 5,10 methylene tetrahydrofolate dehydrogenase, methyltransferase, modified nucleoside, folD |
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