The structure and function of HPr

Authors
Citation
Eb. Waygood, The structure and function of HPr, BIOC CELL B, 76(2-3), 1998, pp. 359-367
Citations number
53
Categorie Soggetti
Cell & Developmental Biology
Journal title
BIOCHEMISTRY AND CELL BIOLOGY-BIOCHIMIE ET BIOLOGIE CELLULAIRE
ISSN journal
08298211 → ACNP
Volume
76
Issue
2-3
Year of publication
1998
Pages
359 - 367
Database
ISI
SICI code
0829-8211(1998)76:2-3<359:TSAFOH>2.0.ZU;2-T
Abstract
Histidine-containing phosphocarrier protein, HPr, was one of the early prot ein tertiary structures determined by two-dimensional H-1-NMR. Tertiary str uctures for HPrs from Escherichia coli, Bacillus subtilis, and Staphylococc us aureus have been obtained by H-1 NMR and the overall folding pattern of HPr is highly conserved, a beta alpha beta beta alpha beta alpha arrangemen t of three alpha-helices overlaying a four-stranded beta-sheet. High-resolu tion structures for HPrs from E. coli and B. subtilis have been obtained us ing N-15- and C-13-labeled proteins. The first application of NMR to the un derstanding of the structure and function of HPr was to describe the phosph ohistidine isomer, N-delta 1-P-histidine in S. aureus phospho-HPr, and the unusual pK(a)s of the His-15 side chain. The pK(a) values for the His-15 im idazole from more recent studies are 5.4 for HPr and 7.8 for phospho-HPr fr om E. coli, for example. A consensus description of the active site is prop osed for HPr and phospho-HPr. In HPr, His-15 has a defined conformation and N-caps helix A, and is thus affected by the helix dipole. His-15 undergoes a small conformational change upon phosphorylation, a movement to allow th e phosphoryl group to be positioned such that it forms hydrogen bonds with the main chain amide nitrogens of residue 16 (not conserved) and Arg-17. In teractions between residue I:! side chain (not conserved: asparagine, serin e, and threonine) and His-15, and between the Arg-17 guanidinium group and the phosphoryl group, are either weak or transitory.