Changing nucleotide specificity of the DEAD-box helicase Hera abrogates communication between the Q-motif and the P-loop

2011 | journal article. A publication with affiliation to the University of Göttingen.

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​Changing nucleotide specificity of the DEAD-box helicase Hera abrogates communication between the Q-motif and the P-loop​
Strohmeier, J.; Hertel, I.; Diederichsen, U. ; Klostermeier, D. & Rudolph, M. G.​ (2011) 
Biological Chemistry392(4) pp. 357​-369​.​ DOI: https://doi.org/10.1515/bc.2011.034 

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Authors
Strohmeier, Julian; Hertel, Ines; Diederichsen, Ulf ; Klostermeier, Dagmar; Rudolph, Markus Georg
Abstract
DEAD-box proteins disrupt or remodel RNA and protein/ RNA complexes at the expense of ATP. The catalytic core is composed of two flexibly connected RecA-like domains. The N-terminal domain contains most of the motifs involved in nucleotide binding and serves as a minimalistic model for helicase/nucleotide interactions. A single conserved glutamine in the so-called Q-motif has been suggested as a conformational sensor for the nucleotide state. To reprogram the Thermus thermophilus RNA helicase Hera for use of oxo- ATP instead of ATP and to investigate the sensor function of the Q-motif, we analyzed helicase activity of Hera Q28E. Crystal structures of the Hera N-terminal domain Q28E mutant (TthDEAD_Q28E) in apo- and ligand-bound forms show that Q28E does change specificity from adenine to 8- oxoadenine. However, significant structural changes accompany the Q28E mutation, which prevent the P-loop from adopting its catalytically active conformation and explain the lack of helicase activity of Hera_Q28E with either ATP or 8-oxo-ATP as energy sources. 8-Oxo-adenosine, 8-oxo-AMP, and 8-oxo-ADP weakly bind to TthDEAD_Q28E but in noncanonical modes. These results indicate that the Q-motif not only senses the nucleotide state of the helicase but could also stabilize a catalytically competent conformation of the Ploop and other helicase signature motifs.
Issue Date
2011
Status
published
Publisher
Walter De Gruyter & Co
Journal
Biological Chemistry 
Organization
Fakultät für Chemie 
ISSN
1437-4315; 1431-6730
Language
English
Sponsor
Swiss National Science Foundation
Notes
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.

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