Sequence‐specific 1H‐NMR assignments and secondary structure of the lipoyl domain of the Bacillus stearothermophilus pyruvate dehydrogenase multienzyme complex.

Abstract

The lipoyl domain (residues 1–85) of the lipoate‐acetyltransferase polypeptide chain of the pyruvate dehydrogenase multienzyme complex of Bacillus stearothermophilus has been subjected to detailed structural analysis by means of two‐dimensional (2D) 1H‐NMR spectroscopy at 400 MHz. Sequence‐specific proton resonance assignments were made, but at this field strength not all of the side‐chain protons could be assigned, especially from complex spin systems like those of leucine, proline and lysine residues. Measurement of short‐range interproton distances identified two extensive regions of β‐sheet, each containing four anti‐parallel peptide strands. The lipoyl‐lysine residue (Lys42) is located in a tight turn at a corner of one sheet, the N‐terminal and C‐terminal residues of the domain are close together in two adjacent β‐strands in the other. The lipoylated and unlipoylated forms of the domain have almost identical spectra, indicating that there is little, if any, conformational change in the protein as a result of the post‐translational modification. Copyright © 1991, Wiley Blackwell. All rights reserved