Strohmeier, JulianJulianStrohmeierHertel, InesInesHertelDiederichsen, UlfUlfDiederichsenKlostermeier, DagmarDagmarKlostermeierRudolph, Markus GeorgMarkus GeorgRudolph2013-02-272021-10-272013-02-272021-10-272011https://resolver.sub.uni-goettingen.de/purl?gro-2/91690DEAD-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.enGoescholarhttps://goescholar.uni-goettingen.de/licensecrystal structure; Hera; hydrogen bond network; nucleotide specificity; 8-oxo-adenosine; ribosome biogenesis.journal_article10.1515/bc.2011.03421391900000288317600010578736https://resolver.sub.uni-goettingen.de/purl?gs-1/8571openAccess