Volume 78, Issue 3 pp. 705-713
Research Article

Structure of the ribosome associating GTPase HflX

Hao Wu

Hao Wu

Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands

National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

Protein Studies Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma

Hao Wu, Lei Sun, and Fabian Blombach contributed equally to this work.

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Lei Sun

Lei Sun

Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands

National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

Hao Wu, Lei Sun, and Fabian Blombach contributed equally to this work.

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Fabian Blombach

Fabian Blombach

Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands

Hao Wu, Lei Sun, and Fabian Blombach contributed equally to this work.

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Stan J.J. Brouns

Stan J.J. Brouns

Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands

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Ambrosius P. L. Snijders

Ambrosius P. L. Snijders

Department of Chemical and Process Engineering, University of Sheffield, Sheffield S1 3JD, UK

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Kristina Lorenzen

Kristina Lorenzen

Department of Biomolecular Mass Spectrometry, Utrecht University, Utrecht, The Netherlands

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Robert H. H. van den Heuvel

Robert H. H. van den Heuvel

Department of Biomolecular Mass Spectrometry, Utrecht University, Utrecht, The Netherlands

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Albert J. R. Heck

Albert J. R. Heck

Department of Biomolecular Mass Spectrometry, Utrecht University, Utrecht, The Netherlands

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Sheng Fu

Sheng Fu

National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

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Xuemei Li

Xuemei Li

National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

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Xuejun C. Zhang

Xuejun C. Zhang

National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

Protein Studies Research Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma

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Zihe Rao

Zihe Rao

National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China

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John van der Oost

Corresponding Author

John van der Oost

Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands

Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands===Search for more papers by this author
First published: 27 August 2009
Citations: 18

Abstract

The HflX-family is a widely distributed but poorly characterized family of translation factor-related guanosine triphosphatases (GTPases) that interact with the large ribosomal subunit. This study describes the crystal structure of HflX from Sulfolobus solfataricus solved to 2.0-Å resolution in apo- and GDP-bound forms. The enzyme displays a two-domain architecture with a novel “HflX domain” at the N-terminus, and a classical G-domain at the C-terminus. The HflX domain is composed of a four-stranded parallel β-sheet flanked by two α-helices on either side, and an anti-parallel coiled coil of two long α-helices that lead to the G-domain. The cleft between the two domains accommodates the nucleotide binding site as well as the switch II region, which mediates interactions between the two domains. Conformational changes of the switch regions are therefore anticipated to reposition the HflX-domain upon GTP-binding. Slow GTPase activity has been confirmed, with an HflX domain deletion mutant exhibiting a 24-fold enhanced turnover rate, suggesting a regulatory role for the HflX domain. The conserved positively charged surface patches of the HflX-domain may mediate interaction with the large ribosomal subunit. The present study provides a structural basis to uncover the functional role of this GTPases family whose function is largely unknown. Proteins 2010. © 2009 Wiley-Liss, Inc.

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