1MUC

STRUCTURE OF MUCONATE LACTONIZING ENZYME AT 1.85 ANGSTROMS RESOLUTION

「1MLE」から置き換えられました

1MUC の概要

• エントリーDOI: 10.2210/pdb1muc/pdb
• 分子名称: MUCONATE LACTONIZING ENZYME, MANGANESE (II) ION (3 entities in total)
• 機能のキーワード: muconate lactonizing enzyme, isomerase
• 由来する生物種: Pseudomonas putida
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 80820.22

構造登録者

Helin, S.,Kahn, P.C.,Guha, B.H.L.,Mallows, D.J.,Goldman, A. (登録日: 1995-09-20, 公開日: 1996-07-11, 最終更新日: 2024-02-14)

主引用文献

Helin, S.,Kahn, P.C.,Guha, B.L.,Mallows, D.G.,Goldman, A.
The refined X-ray structure of muconate lactonizing enzyme from Pseudomonas putida PRS2000 at 1.85 A resolution.
J.Mol.Biol., 254:918-941, 1995

PubMed Abstract: We report here the refined X-ray crystal structure of muconate lactonizing enzyme (MLE) from Pseudomonas putida PRS2000 at a resolution of 1.85 A with an R-factor of 16.8%. An enzyme from the beta-ketoadipate pathway, MLE catalyses the conversion of cis,cis-muconate to muconolactone. It is a homo-octamer, one monomer consisting of 373 amino acid residues. MLE has two large domains and a C-terminal subdomain: an alpha + beta domain, an alpha beta-barrel domain and a C-terminal meandering subdomain. The alpha beta-barrel domain is highly irregular. Its structure is (beta/alpha)7 beta, with the structural role of the last alpha-helix being replaced by both the C-terminal subdomain and part of the N-terminal domain. The fifth, seventh and eighth barrel strands are unusual because they have left-handed twist about their axes. The strand crossing angles also vary enormously, from +9 degrees to -69 degrees; the first and last strands, which close the barrel, cross at an angle of -69 degrees, making extensive strand-strand hydrogen bonding impossible. The first barrel strand is also unusual because it starts in the N-terminal domain and forms hydrogen bonds to the C-terminal subdomain beta-sheet as well as to its neighbouring strands in the barrel. It thus cements the whole protein together. As in other alpha beta-barrel proteins, the active site of MLE, present in each subunit is at the C-terminal ends of the barrel beta-strands. The active site cleft contains an essential manganese ion, is lined with charged and other polar residues, and contains many of the crystallographic water molecules. The manganese ion is octahedrally co-ordinated to three side-chain carboxylate groups and three water molecules, and is at the centre of a radiating web of ionic and hydrogen-bonding interactions. Additionally, two water molecules are buried in the centre of the barrel and two hydrophilic side-chains (Lys167 and Arg196) make both hydrophobic and hydrophilic packing interactions with much of the barrel interior. The barrel interior is thus also unusual because it is so hydrophilic; the dominating force appears to be the need to solvate the metal ion effectively. This might account for the irregularity of the barrel. The catalytic mechanism has been investigated by docking both substrate and product in the active site with the C-COO- of muconolactone superimposed on the corresponding atoms of cis,cis-muconate. In agreement with earlier kinetic and spectroscopic results, the manganese ion does not interact directly with substrate or product.(ABSTRACT TRUNCATED AT 400 WORDS)

PubMed: 7500361
DOI: 10.1006/jmbi.1995.0666

実験手法

X-RAY DIFFRACTION (1.85 Å)