Journal
JOURNAL OF BIOLOGICAL CHEMISTRY
Volume 282, Issue 38, Pages 28106-28116Publisher
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
DOI: 10.1074/jbc.M704326200
Keywords
-
Categories
Funding
- NCRR NIH HHS [S10RR020932] Funding Source: Medline
- NIGMS NIH HHS [GM 50380, GM61791] Funding Source: Medline
Ask authors/readers for more resources
Our crystallographic studies have shown that two active center loops (an inner loop formed by residues 401-413 and outer loop formed by residues 541-557) of the El component of the Escherichia coli pyruvate dehydrogenase complex become organized only on binding a substrate analog that is capable of forming a stable thiamin diphosphate-bound covalent intermediate. We showed that residue His-407 on the inner loop has a key role in the mechanism, especially in the reductive acetylation of the E. coli dihydrolipoamide transacetylase component, whereas crystallographic results showed a role of this residue in a disorder-order transformation of these two loops, and the ordered conformation gives rise to numerous new contacts between the inner loop and the active center. We present mapping of the conserved residues on the inner loop. Kinetic, spectroscopic, and crystallographic studies on some inner loop variants led us to conclude that charged residues flanking His-407 are important for stabilization/ordering of the inner loop thereby facilitating completion of the active site. The results further suggest that a disorder to order transition of the dynamic inner loop is essential for substrate entry to the active site, for sequestering active site chemistry from undesirable side reactions, as well as for communication between the El and E2 components of the E. coli pyruvate dehydrogenase multienzyme complex.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available