Premium
Enhanced internal dynamics of a membrane transport protein during substrate translocation
Author(s) -
Döring KLAUS,
Surrey Thomas,
Grünewald Sylvia,
John Edgar,
Jähnig Fritz
Publication year - 2000
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.9.11.2246
Subject(s) - protein dynamics , substrate (aquarium) , biophysics , lactose permease , chemistry , nanosecond , conformational change , membrane transport protein , protein structure , dynamics (music) , chemical physics , crystallography , membrane protein , membrane , stereochemistry , biochemistry , biology , physics , ecology , laser , acoustics , optics
Conformational changes are essential for the activity of many proteins. If, or how fast, internal fluctuations are related to slow conformational changes that mediate protein function is not understood. In this study, we measure internal fluctuations of the transport protein lactose permease in the presence and absence of substrate by tryptophan fluorescence spectroscopy. We demonstrate that nanosecond fluctuations of α‐helices are enhanced when the enzyme transports substrate. This correlates with previously published kinetic data from transport measurements showing that millisecond conformational transitions of the substrate‐loaded carrier are faster than those in the absence of substrate. These findings corroborate the hypothesis of the hierarchical model of protein dynamics that predicts that slow conformational transitions are based on fast, thermally activated internal motions.