2VU1: Biosynthetic Thiolase From Z. Ramigera. Complex Of With O- Pantheteine-11-Pivalate

Citation:
Abstract
Thioesters are more reactive than oxoesters, and thioester chemistry is important for the reaction mechanisms of many enzymes, including the members of the thiolase superfamily, which play roles in both degradative and biosynthetic pathways. In the reaction mechanism of the biosynthetic thiolase, the thioester moieties of acetyl-CoA and the acetylated catalytic cysteine react with each other, forming the product acetoacetyl-CoA. Although a number of studies have been carried out to elucidate the thiolase reaction mechanism at the atomic level, relatively little is known about the factors determining the affinity of thiolases towards their substrates. We have carried out crystallographic studies on the biosynthetic thiolase from Zoogloea ramigera complexed with CoA and three of its synthetic analogues to compare the binding modes of these related compounds. The results show that both the CoA terminal SH group and the side chain SH group of the catalytic Cys89 are crucial for the correct positioning of substrate in the thiolase catalytic pocket. Furthermore, calorimetric assays indicate that the mutation of Cys89 into an alanine significantly decreases the affinity of thiolase towards CoA. Thus, although the sulfur atom of the thioester moiety is important for the reaction mechanism of thioester-dependent enzymes, its specific properties can also affect the affinity and competent mode of binding of the thioester substrates to these enzymes.
PDB ID: 2VU1Download
MMDB ID: 67579
PDB Deposition Date: 2008/5/19
Updated in MMDB: 2008/12
Experimental Method:
x-ray diffraction
Resolution: 1.51  Å
Source Organism:
Similar Structures:
Biological Unit for 2VU1: tetrameric; determined by author and by software (PISA)
Molecular Components in 2VU1
Label Count Molecule
Proteins (4 molecules)
4
Acetyl-coa Acetyltransferase
Molecule annotation
Chemicals (8 molecules)
1
2
2
1
3
5
* Click molecule labels to explore molecular sequence information.

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