Premium
Inter‐domain orientation and motions in VAT‐N explored by residual dipolar couplings and 15 N backbone relaxation
Author(s) -
Deshmukh Mandar V.,
John Michael,
Coles Murray,
Peters Jürgen,
Baumeister Wolfgang,
Kessler Horst
Publication year - 2006
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1837
Subject(s) - chemistry , relaxation (psychology) , crystallography , residual , domain (mathematical analysis) , orientation (vector space) , substrate (aquarium) , residual dipolar coupling , dipole , chemical physics , stereochemistry , geometry , nuclear magnetic resonance spectroscopy , algorithm , psychology , social psychology , mathematical analysis , oceanography , mathematics , organic chemistry , computer science , geology
The N ‐terminal domain of VAT (Valosine‐containing protein‐like ATPase of Thermoplasma acidophilum ), VAT‐N (20.5 kDa), is considered to be the primary substrate‐recognition site of the complex. The solution structure of VAT‐N derived in our laboratory using conventionally obtained NMR restraints shows the existence of two equally sized sub‐domains, VAT‐Nn and VAT‐Nc, together forming a kidney‐shaped overall structure. The putative substrate‐binding site of VAT‐N involves free loops and a highly charged groove located on the surface of the protein. Alternatively, the opening of the cleft between the domains to accommodate substrate has been proposed to be part of the functional mechanism. We have used the residual dipolar couplings (RDCs) obtained in a bicelle medium to refine the structure of VAT‐N. The long‐range information available from RDCs both defines the sub‐domain orientation and probes possible inter‐domain motions. In addition, 15 N backbone relaxation data were obtained and analysed within the model‐free framework. Together, the data provides a refined structure with improved local geometry, but with the overall kidney shape intact. Further, the protein is rigid overall, with no evidence of inter‐domain motions. Copyright © 2006 John Wiley & Sons, Ltd.