Structure and mechanism of a bacterial t6A biosynthesis system.
Nucleic Acids Res
; 46(3): 1395-1411, 2018 02 16.
Article
em En
| MEDLINE
| ID: mdl-29309633
ABSTRACT
The universal N(6)-threonylcarbamoyladenosine (t6A) modification at position 37 of ANN-decoding tRNAs is central to translational fidelity. In bacteria, t6A biosynthesis is catalyzed by the proteins TsaB, TsaC/TsaC2, TsaD and TsaE. Despite intense research, the molecular mechanisms underlying t6A biosynthesis are poorly understood. Here, we report biochemical and biophysical studies of the t6A biosynthesis system from Thermotoga maritima. Small angle X-ray scattering analysis reveals a symmetric 22 stoichiometric complex of TsaB and TsaD (TsaB2D2), as well as 222 complex (TsaB2D2E2), in which TsaB acts as a dimerization module, similar to the role of Pcc1 in the archaeal system. The TsaB2D2 complex is the minimal platform for the binding of one tRNA molecule, which can then accommodate a single TsaE subunit. Kinetic data demonstrate that TsaB2D2 alone, and a TsaB2D2E1 complex with TsaE mutants deficient in adenosine triphosphatase (ATPase) activity, can catalyze only a single cycle of t6A synthesis, while gel shift experiments provide evidence that the role of TsaE-catalyzed ATP hydrolysis occurs after the release of product tRNA. Based on these results, we propose a model for t6A biosynthesis in bacteria.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
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Biossíntese de Proteínas
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RNA de Transferência
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Adenosina
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Thermotoga maritima
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Ligases
Idioma:
En
Revista:
Nucleic Acids Res
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Estados Unidos