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Structural plasticity of staphylococcal nuclease probed by perturbation with pressure and pH
Author(s) -
Kitahara Ryo,
Hata Kazumi,
Maeno Akihiro,
Akasaka Kazuyuki,
Chimenti Michael S.,
GarciaMoreno E. Bertrand,
Schroer Martin A.,
Jeworrek Christoph,
Tolan Metin,
Winter Roland,
Roche Julien,
Roumestand Christian,
Montet de Guillen Karine,
Royer Catherine A.
Publication year - 2011
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.22966
Subject(s) - nuclease , plasticity , chemistry , biophysics , biology , materials science , biochemistry , composite material , enzyme
Abstract The ionization of internal groups in proteins can trigger conformational change. Despite this being the structural basis of most biological energy transduction, these processes are poorly understood. Small angle X‐ray scattering (SAXS) and nuclear magnetic resonance (NMR) spectroscopy experiments at ambient and high hydrostatic pressure were used to examine how the presence and ionization of Lys‐66, buried in the hydrophobic core of a stabilized variant of staphylococcal nuclease, affect conformation and dynamics. NMR spectroscopy at atmospheric pressure showed previously that the neutral Lys‐66 affects slow conformational fluctuations globally, whereas the effects of the charged form are localized to the region immediately surrounding position 66. Ab initio models from SAXS data suggest that when Lys‐66 is charged the protein expands, which is consistent with results from NMR spectroscopy. The application of moderate pressure (<2 kbar) at pH values where Lys‐66 is normally neutral at ambient pressure left most of the structure unperturbed but produced significant nonlinear changes in chemical shifts in the helix where Lys‐66 is located. Above 2 kbar pressure at these pH values the protein with Lys‐66 unfolded cooperatively adopting a relatively compact, albeit random structure according to Kratky analysis of the SAXS data. In contrast, at low pH and high pressure the unfolded state of the variant with Lys‐66 is more expanded than that of the reference protein. The combined global and local view of the structural reorganization triggered by ionization of the internal Lys‐66 reveals more detectable changes than were previously suggested by NMR spectroscopy at ambient pressure. Proteins 2011. © 2011 Wiley‐Liss, Inc.