Open AccessA 1 H‐NMR study of the transcription factor 1 from Bacillus subtilis phage SPO1 by selective 2 H‐labeling
Author(s) -
REISMAN Joseph M.,
HSU Victor L.,
JARIELENCONTRE Isabelle,
LECOU Christian,
SAYRE Michael H.,
KEARNS David R.,
PARELLO Joseph
Publication year - 1993
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1993.tb17830.x
Subject(s) - bacillus subtilis , rotational correlation time , chemistry , nuclear overhauser effect , monomer , spin diffusion , nuclear magnetic resonance spectroscopy , crystallography , two dimensional nuclear magnetic resonance spectroscopy , stereochemistry , molecule , diffusion , physics , biology , genetics , organic chemistry , bacteria , polymer , thermodynamics
1 H‐NMR experiments have been performed on transcription factor 1 (TF1) encoded by Bacillus subtilis phage SPO1. To study this 22‐kDa homodimeric DNA‐binding protein, a selective 2 H‐labeling strategy has been employed. Complete sequence‐specific assignments of all the resonances from the five aromatic residues were determined by a modified standard sequential‐assignment procedure. The reduced contribution of spin diffusion upon the long‐mixing‐time nuclear‐Overhauser‐enhancement spectroscopy for the selectively 2 H‐labeled variants, as opposed to the fully 1 H‐containing protein, has allowed for the identification of the spin system and of the long‐range dipolar contacts between Phe28 and Phe47 protons in the protein core and between Phe61 and Phe97 protons. The latter suggests an interaction between the proposed ß‐ribbon DNA‐binding arm and the carboxy terminus of the paired monomer. A previously proposed TF1 structural model [Geiduschek, E. P., Schneider, G. J. & Sayre, M. H. (1990) J. Struct. Biol. 104 , 84–90)] has been modified using constrained‐energy‐minimization calculations incorporating the experimentally determined set of aromatic‐to‐aromatic contacts. This new model has been analyzed with regard to the relative mobility and the relative solvent accessibility of the aromatic residues which have been measured by the nonselective T 1 relaxation times of the aromatic resonances for the fully 1 H‐containing protein and the relaxation time enhancements upon selective 2 H‐labeling, respectively.