Pressure-induced changes in the solution structure of the GB1 domain of protein G.
The solution structure of the GB1 domain of protein G at a pressure of 2 kbar is presented. The structure was calculated as a change from an energy-minimised low-pressure structure using (1)H chemical shifts. Two separate changes can be characterised: a compression/distortion, which is linear with pressure; and a stabilisation of an alternative folded state. On application of pressure, linear chemical shift changes reveal that the backbone structure changes by about 0.2 A root mean square, and is compressed by about 1% overall. The alpha-helix compresses, particularly at the C-terminal end, and moves toward the beta-sheet, while the beta-sheet is twisted, with the corners closest to the alpha-helix curling up towards it. The largest changes in structure are along the second beta-strand, which becomes more twisted. This strand is where the protein binds to IgG. Curved chemical shift changes with pressure indicate that high pressure also populates an alternative structure with a distortion towards the C-terminal end of the helix, which is likely to be caused by insertion of a water molecule.
Wilton
David J
DJ
Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, United Kingdom.
Tunnicliffe
Richard B
RB
Kamatari
Yuji O
YO
Akasaka
Kazuyuki
K
Williamson
Mike P
MP
D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics*; D008969:Molecular Sequence Data; D011312:Pressure; D011485:Protein Binding / Q000235:genetics; D011487:Protein Conformation; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics
D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus