Premium
The functional importance of structural differences between the mannitol‐specific IIA mannitol and the regulatory IIA nitrogen
Author(s) -
Van Montfort Rob L. M.,
Dijkstra Bauke W.
Publication year - 1998
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 - 10.1002/pro.5560071019
Subject(s) - active site , biochemistry , enzyme , chemistry , escherichia coli , phosphotransferase , residue (chemistry) , binding site , pep group translocation , stereochemistry , biology , gene
The three‐dimensional structures of the IIA domain of the mannitol‐specific phosphoenol‐pyruvate dependent phos‐photransferase system (PTS) of Escherichia coli and the regulatory IIA ntr enzyme have been compared. The enzymes are 20% identical in sequence and contain the sequence motif specific for IIA proteins belonging to the mannitol‐fructose family of the PTS. The fold of the enzymes is nearly identical, which confirms their evolution from a common ancestor. Moreover, the phosphorylation site of IIA mtl (His65) and one of the observed conformations of the active site Arg49 are extremely similar to their equivalents (His73 and Arg57) in IIA ntr . In contrast, His l20, the equivalent of the second active site His111 of IIA mtl , is not located in the active site of IIA ntr but points into the solvent on the other side of the molecule. The different position of His120 makes it unlikely that this residue assists in phosphoryl transfer in the regulatory IIA ntr s. As His120 is conserved in all IIA ntr enzymes, it could have an essential role in the recognition of the target protein of IIA ntr .