PDBsum entry 1m1t

Transferase

PDB id: 1m1t

Contents

Protein chains

392 a.a. *

Ligands

SO4 ×4

GOL ×4

Waters ×1177

* Residue conservation analysis

PDB id:

1m1t

Name:

Transferase

Title:

Biosynthetic thiolase, q64a mutant

Structure:

Acetyl-coa acetyltransferase. Chain: a, b, c, d. Synonym: acetoacetyl-coa thiolase. Biosynthetic thiolase. Engineered: yes. Mutation: yes

Source:

Zoogloea ramigera. Organism_taxid: 350. Expressed in: escherichia coli. Expression_system_taxid: 562

Biol. unit:

Tetramer (from PQS)

Resolution:

1.94Å R-factor: 0.201 R-free: 0.245

Authors:

P.Kursula,J.Ojala,A.-M.Lambeir,R.K.Wierenga

Key ref:

P.Kursula et al. (2002). The catalytic cycle of biosynthetic thiolase: a conformational journey of an acetyl group through four binding modes and two oxyanion holes. Biochemistry, 41, 15543-15556. PubMed id: 12501183 DOI: 10.1021/bi0266232

Date:

20-Jun-02 Release date: 29-Nov-02

Protein chains

P07097  (THIL_SHIZO) -  Acetyl-CoA acetyltransferase from Shinella zoogloeoides

Seq: 392 a.a.

Struc: 392 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.2.3.1.9 - acetyl-CoA C-acetyltransferase.
• Pathway: Mevalonate Biosynthesis
• Reaction: 2 acetyl-CoA = acetoacetyl-CoA + CoA

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1021/bi0266232

Biochemistry 41:15543-15556 (2002)

PubMed id: 12501183

The catalytic cycle of biosynthetic thiolase: a conformational journey of an acetyl group through four binding modes and two oxyanion holes.

P.Kursula, J.Ojala, A.M.Lambeir, R.K.Wierenga.

ABSTRACT

Biosynthetic thiolase catalyzes the formation of acetoacetyl-CoA from two molecules of acetyl-CoA. This is a key step in the synthesis of many biological compounds, including steroid hormones and ketone bodies. The thiolase reaction involves two chemically distinct steps; during acyl transfer, an acetyl group is transferred from acetyl-CoA to Cys89, and in the Claisen condensation step, this acetyl group is further transferred to a second molecule of acetyl-CoA, generating acetoacetyl-CoA. Here, new crystallographic data for Zoogloea ramigera biosynthetic thiolase are presented, covering all intermediates of the thiolase catalytic cycle. The high-resolution structures indicate that the acetyl group goes through four conformations while being transferred from acetyl-CoA via the acetylated enzyme to acetoacetyl-CoA. This transfer is catalyzed in a rigid cavity lined by mostly hydrophobic side chains, in addition to the catalytic residues Cys89, His348, and Cys378. The structures highlight the importance of an oxyanion hole formed by a water molecule and His348 in stabilizing the negative charge on the thioester oxygen atom of acetyl-CoA at two different steps of the reaction cycle. Another oxyanion hole, composed of the main chain nitrogen atoms of Cys89 and Gly380, complements a negative charge of the thioester oxygen anion of the acetylated intermediate, stabilizing the tetrahedral transition state of the Claisen condensation step. The reactivity of the active site may be modulated by hydrogen bonding networks extending from the active site toward the back of the molecule.