1abf
From Proteopedia
SUBSTRATE SPECIFICITY AND AFFINITY OF A PROTEIN MODULATED BY BOUND WATER MOLECULES
Structural highlights
Function[ARAF_ECOLI] Involved in the high-affinity L-arabinose membrane transport system. Binds with high affinity to arabinose, but can also bind D-galactose (approximately 2-fold reduction) and D-fucose (approximately 40-fold reduction). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedWater molecules influence molecular interactions in all biological systems, yet it is extremely difficult to understand their effects in precise atomic detail. Here we present evidence, based on highly refined atomic structures of the complexes of the L-arabinose-binding protein with L-arabinose, D-fucose and D-galactose, that bound water molecules, coupled with localized conformational changes, can govern substrate specificity and affinity. The atoms common to the three sugars are identically positioned in the binding site and the same nine strong hydrogen bonds are formed in all three complexes. Two hydrogen-bonded water molecules in the site contribute further to tight binding of L-arabinose but create an unfavourable interaction with the methyl group of D-fucose. Equally tight binding of D-galactose is attained by the replacement of one of the hydrogen-bonded water molecules by its--CH2OH group, coordinated with localized structural changes which include a shift and redirection of the hydrogen-bonding interactions of the other water molecule. These observations illustrate how ordered water molecules can contribute directly to the properties of proteins by influencing their interaction with ligands. Substrate specificity and affinity of a protein modulated by bound water molecules.,Quiocho FA, Wilson DK, Vyas NK Nature. 1989 Aug 3;340(6232):404-7. PMID:2818726[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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