G673 could be a novel mutational hot spot for intragenic suppressors of pheS5 lesion in Escherichia coli

MicrobiologyOpen

Thangaraj Ponmani¹ 

[1] Department of Molecular Biology, School of Biological Sciences, Centre for Excellence in Genomic Sciences, Centre for Advanced Studies in functional and organismal Genomics, Madurai Kamaraj University [University with Potential for Excellence], Madurai, India

关键词: Escherichia coli;    hot spot;    intragenic suppressor;    PheRS enzyme;    pheS5.;   

DOI  :  10.1002/mbo3.161

来源: Wiley

【 摘 要 】

Abstract

The pheS5 Ts mutant of Escherichia coli defined by a G₂₉₃ → A₂₉₃ transition, which is responsible for thermosensitive Phenylalanyl-tRNA synthetase has been well studied at both biochemical and molecular level but genetic analyses pertaining to suppressors of pheS5 were hard to come by. Here we have systematically analyzed a spectrum of Temperature-insensitive derivatives isolated from pheS5 Ts mutant and identified two intragenic suppressors affecting the same base pair coordinate G₆₇₃ (pheS19 defines G₆₇₃ → T₆₇₃; Gly₂₂₅ → Cys₂₂₅ and pheS28 defines G₆₇₃ → C₆₇₃; Gly₂₂₅ → Arg₂₂₅). In fact in the third derivative, the intragenic suppressor originally named pheS43 (G₆₇₃ → C₆₇₃transversion) is virtually same as pheS28. In the fourth case, the very pheS5 lesion itself has got changed from A₂₉₃ → T₂₉₃ (named pheS40). Cloning of pheS⁺, pheS5, pheS5-pheS19, pheS5-pheS28 alleles into pBR322 and introduction of these clones into pheS5 mutant revealed that excess of double mutant protein is not at all good for the survival of cells at 42°C. These results clearly indicate a pivotal role for Gly₂₂₅ in the structural/functional integrity of alpha subunit of E. coli PheRS enzyme and it is proposed that G₆₇₃ might define a hot spot for intragenic suppressors of pheS5.

【 授权许可】

CC BY   
© 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

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