PDBsum entry 1b8g

Lyase

PDB id: 1b8g

Contents

Protein chains

421 a.a. *

Ligands

PLP ×2

Waters ×174

* Residue conservation analysis

PDB id:

1b8g

Name:

Lyase

Title:

1-aminocyclopropane-1-carboxylate synthase

Structure:

Protein (1-aminocyclopropane-1-carboxylate synthase). Chain: a, b. Synonym: acc synthase, s-adenosyl-l-methionine methylthioadenosine- lyase. Engineered: yes

Source:

Malus x domestica. Organism_taxid: 3750. Tissue: fruit cortical tissue. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PQS)

Resolution:

2.37Å R-factor: 0.179 R-free: 0.242

Authors:

G.Capitani,E.Hohenester,L.Feng,P.Storici,J.F.Kirsch,J.N.Jansonius

Key ref:

G.Capitani et al. (1999). Structure of 1-aminocyclopropane-1-carboxylate synthase, a key enzyme in the biosynthesis of the plant hormone ethylene. J Mol Biol, 294, 745-756. PubMed id: 10610793 DOI: 10.1006/jmbi.1999.3255

Date:

31-Jan-99 Release date: 26-Jan-00

Protein chains

P37821  (1A1C_MALDO) -  1-aminocyclopropane-1-carboxylate synthase from Malus domestica

Seq: 473 a.a.

Struc: 421 a.a.

Enzyme reactions

• Enzyme class 1: E.C.1.4.-.-
• Enzyme class 2: E.C.4.4.1.14 - 1-aminocyclopropane-1-carboxylate synthase.

Pathway:

• Reaction: S-adenosyl-L-methionine = 1-aminocyclopropane-1-carboxylate + S-methyl- 5'-thioadenosine + H⁺
• Cofactor: Pyridoxal 5'-phosphate

Pyridoxal 5'-phosphate (Bound ligand (Het Group name = PLP) matches with 93.75% similarity)

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

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

reference

DOI no: 10.1006/jmbi.1999.3255

J Mol Biol 294:745-756 (1999)

PubMed id: 10610793

Structure of 1-aminocyclopropane-1-carboxylate synthase, a key enzyme in the biosynthesis of the plant hormone ethylene.

G.Capitani, E.Hohenester, L.Feng, P.Storici, J.F.Kirsch, J.N.Jansonius.

ABSTRACT

The 2.4 A crystal structure of the vitamin B6-dependent enzyme 1-aminocyclopropane-1-carboxylate (ACC) synthase is described. This enzyme catalyses the committed step in the biosynthesis of ethylene, a plant hormone that is responsible for the initiation of fruit ripening and for regulating many other developmental processes. ACC synthase has 15 % sequence identity with the well-studied aspartate aminotransferase, and a completely different catalytic activity yet the overall folds and the active sites are very similar. The new structure together with available biochemical data enables a comparative mechanistic analysis that largely explains the catalytic roles of the conserved and non-conserved active site residues. An external aldimine reaction intermediate (external aldimine with ACC, i.e. with the product) has been modeled. The new structure provides a basis for the rational design of inhibitors with broad agricultural applications.

Selected figure(s)

Figure 3.
Figure 3. Active site views of ACC synthase. (a) Stereo view of the ACC synthase active site with the most import- ant residues labeled (prepared with the program O (Jones & Kjeldgaard, 1991)). Residues within a sphere of 11 Å of the cofactor are depicted in yellow and atom colors, and shown in each two alternative conformation. Tyr85, which is contributed by the neighboring subunit, is labeled with an asterisk. (b) Detailed stereo view of the ACC synthase active site (subunit B), showing the covalent linkage between the cofactor and Lys273. The final 2Fo - Fc map, con- toured at 1.2s, is superimposed on the atomic model. The model is depicted in yellow and atom colors. The unde- fined additional density in front of the cofactor and modeled as three water molecules (red spheres) is visible at the top right. Prepared with O.

Figure 4.
Figure 4. Stereo view of the superposition of the ACC synthase and AATase active sites. Residues within 11 Å of the cofactors are shown. ACC synthase is depicted in yellow, AATase in green. Residue labels for ACC synthase appear in gold, those for AATase residues in black. Tyr85 (ACC synthase) and Tyr70 and Arg292 (AATase) are con- tributed by the neighboring subunit and are labeled with an asterisk. Prepared with O.

The above figures are reprinted by permission from Elsevier: J Mol Biol (1999, 294, 745-756) copyright 1999.

Figures were selected by an automated process.