Role of D-aminoacyl-tRNA deacylase beyond chiral proofreading as a cellular defense against glycine mischarging by AlaRS

Strict L-chiral rejection through Gly- Pro motif during chiral proofreading underlies the inability of D-aminoacyl-tRNA deacylase (DTD) to discriminate between D-amino acids and achiral glycine. The consequent Gly-tRNA 'misediting paradox' is resolved by EF-Tu in the cell. Here, we show th...

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Veröffentlicht in:eLife 2017-03, Vol.6
Hauptverfasser: Pawar, Komal Ishwar, Suma, Katta, Seenivasan, Ayshwarya, Kuncha, Santosh Kumar, Routh, Satya Brata, Kruparani, Shobha P, Sankaranarayanan, Rajan
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Sprache:eng
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Zusammenfassung:Strict L-chiral rejection through Gly- Pro motif during chiral proofreading underlies the inability of D-aminoacyl-tRNA deacylase (DTD) to discriminate between D-amino acids and achiral glycine. The consequent Gly-tRNA 'misediting paradox' is resolved by EF-Tu in the cell. Here, we show that DTD's active site architecture can efficiently edit mischarged Gly-tRNA species four orders of magnitude more efficiently than even AlaRS, the only ubiquitous cellular checkpoint known for clearing the error. Also, DTD knockout in AlaRS editing-defective background causes pronounced toxicity in even at low-glycine levels which is alleviated by alanine supplementation. We further demonstrate that DTD positively selects the universally invariant tRNA -specific G3•U70. Moreover, DTD's activity on non-cognate Gly-tRNA is conserved across all bacteria and eukaryotes, suggesting DTD's key cellular role as a glycine deacylator. Our study thus reveals a hitherto unknown function of DTD in cracking the universal mechanistic dilemma encountered by AlaRS, and its physiological importance.
ISSN:2050-084X
2050-084X
DOI:10.7554/eLife.24001