Abstract:
:Cysteine residues introduced by site-directed mutagenesis have been used to probe the conformation and dynamics of two receptors in the E. coli chemotaxis pathway. (a) Thermal motions of the polypeptide backbone were investigated in the periplasmic D-galactose and D-glucose receptor, a globular protein of known structure. Disulfide bond formation between pairs of engineered sulfhydryls were used to trap collisions during the relative motions of surface alpha-helices I and X. Motions with amplitudes ranging from 4.5 to 15.2 A were detected on timescales ranging from 10(-4) to 10(-1) s, respectively. These results suggest that thermal backbone motions may have larger amplitudes than previously thought. (b) Conformational features of the transmembrane aspartate transducer have been investigated. Engineered sulfhydryls were used to ascertain the location and orientations of two putative transmembrane alpha-helices in the primary structure, to investigate the packing of these helices, to determine the oligomer and surface structures, and to detect thermal and ligand-induced dynamics of the polypeptide backbone. A model for the folded conformation of the transducer oligomer is reviewed.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Careaga CL,Falke JJdoi
10.1016/S0006-3495(92)81806-4subject
Has Abstractpub_date
1992-04-01 00:00:00pages
209-16; discussion 217-9issue
1eissn
0006-3495issn
1542-0086pii
S0006-3495(92)81806-4journal_volume
62pub_type
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