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Genetic Analysis Identifies a Function for the queC(ybax)Gene Product at an Initial Step in the Queuosine Biosynthetic Pathway in Escherichia coli

Gaur, Rahul and Varshney, Umesh (2005) Genetic Analysis Identifies a Function for the queC(ybax)Gene Product at an Initial Step in the Queuosine Biosynthetic Pathway in Escherichia coli. In: Journal of Bacteriology, 187 (20). pp. 6893-6901.

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Abstract

Queuosine (Q), one of the most complex modifications occurring at the wobble position of tRNAs with GUN anticodons, is implicated in a number of biological, activities, including accuracy of decoding, virulence,and cellular differentiation. Despite these important implications, its biosynthetic pathway has remained unresolved. Earlier, we observed that a naturally occurring strain of Escherichia coli B105 lacked Q modification in the tRNAs. In the present study, we developed a genetic screen to map the defect in E. coli B105 to a single gene, queC (renamed from ybaX), predicted to code for a 231-amino-acid-long protein with a pI of 5.6. As analyzed by mobility of $tRNA^{Tyr}$ on acid urea gels and two-dimensional thin-layer chromatography of the modified nucleosides, expression of QueC from a plasmid-borne copy confers a $Q^{+}$ phenotype to E. coli B105. Further, analyses of $tRNA^{Tyr}$ from E.coli JE10651 (queA mutant), its derivative generated by deletion of chromosomal queC (queA \Delta queC), and E. coli JE7325, deficient in converting $preQ_{0}$ to $preQ_{1}$, have provided the first genetic evidence for the involvement of QueC at a step leading to production of $preQ_{0}$,the first known intermediate in the generally accepted pathway thatutilizes GTP as the starting molecule. In addition, we discuss thepossibilities of collaboration of QueC with other cellular proteins inthe production of $preQ_{0}$.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to American Society for Microbiology.
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 30 Nov 2005
Last Modified: 27 Aug 2008 11:35
URI: http://eprints.iisc.ernet.in/id/eprint/4229

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