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Modulation of the protein environment in the hydrophilic pore of the ammonia transporter protein AmtB upon GlnK protein binding
Author(s) -
Ishikita Hiroshi
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.07.085
Subject(s) - chemistry , ammonia , plasma protein binding , ammonium , binding protein , atp binding cassette transporter , biochemistry , transporter , stereochemistry , gene , organic chemistry
The conduction of ammonia/ammonium (NH 3 / NH 4 +) through the channel protein AmtB is inhibited by the binding of the signal transduction protein GlnK. In the AmtB–GlnK binding interface, there exists anNH 3 / NH 4 +binding site – Am6. The calculated p K a values at the Am6 sites in both the AmtB–GlnK complex and isolated AmtB implies the dominance of an uncharged NH 3 state. The GlnK protein binding causes a significant downshift in the Am6 p K a value of the AmtB. However, this downshift is perfectly compensated by the reorientation of the protein backbone (carbonyl group of Cys312 from the AmtB part) upon AmtB–GlnK complex formation.