Time-resolved fluorescence studies on the dihydrolipoyl transacetylase (E 2) component of the pyruvate dehydrogenase complex from Azotobacter vinelandii

Abstract

The dihydrolipoyl transacetylase (E 2) component of A. vinelandii PDC and its lipoyl domain shows similar dynamic properties as revealed with fluorescence anisotropy decay of lipoyl-bound IAANS. The lipoyl domain (32.6 kDa), containing three almost identical subdomains shows a mode of rotation characteristic for a protein of about 30 kDa. A similar rotation is found in E 2, indicating an independent rotational mobility of the whole domain in the multimeric E 2 core (1.6MDa). No independent rotation of a single lipoyl subdomain (10 kDa) is observed. The E 1 component, in contrast to the E 3 component, shows interaction with the lipoyl domain.