1DCN

INACTIVE MUTANT H162N OF DELTA 2 CRYSTALLIN WITH BOUND ARGININOSUCCINATE

1DCN の概要

• エントリーDOI: 10.2210/pdb1dcn/pdb
• 分子名称: DELTA 2 CRYSTALLIN, ARGININOSUCCINATE (3 entities in total)
• 機能のキーワード: eye lens protein, delta 2 crystallin, argininosuccinate lyase
• 由来する生物種: Anas platyrhynchos
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 198293.46

構造登録者

Vallee, F.,Turner, M.A.,Lindley, P.,Howell, P.L. (登録日: 1998-10-29, 公開日: 1999-04-27, 最終更新日: 2024-10-02)

主引用文献

Vallee, F.,Turner, M.A.,Lindley, P.L.,Howell, P.L.
Crystal structure of an inactive duck delta II crystallin mutant with bound argininosuccinate.
Biochemistry, 38:2425-2434, 1999

PubMed Abstract: Delta-crystallin, the major soluble protein component of avian and reptilian eye lenses, is highly homologous to the urea cycle enzyme, argininosuccinate lyase (ASL). In duck lenses, there are two highly homologous delta crystallins, delta I and delta II, that are 94% identical in amino acid sequence. While delta II crystallin has been shown to exhibit ASL activity in vitro, delta I is enzymatically inactive. The X-ray structure of a His to Asn mutant of duck delta II crystallin (H162N) with bound argininosuccinate has been determined to 2.3 A resolution using the molecular replacement technique. The overall fold of the protein is similar to other members of the superfamily to which this protein belongs, with the active site located in a cleft formed by three different monomers in the tetramer. The active site of the H162N mutant structure reveals that the side chain of Glu 296 has a different orientation relative to the homologous residue in the H91N mutant structure [Abu-Abed et al. (1997) Biochemistry 36, 14012-14022]. This shift results in the loss of the hydrogen bond between His 162 and Glu 296 seen in the H91N and turkey delta I crystallin structures; this H-bond is believed to be crucial for the catalytic mechanism of ASL/delta II crystallin. Argininosuccinate was found to be bound to residues in each of the three monomers that form the active site. The fumarate moiety is oriented toward active site residues His 162 and Glu 296 and other residues that are part of two of the three highly conserved regions of amino acid sequence in the superfamily, while the arginine moiety of the substrate is oriented toward residues which belong to either domain 1 or domain 2. The analysis of the structure reveals that significant conformational changes occur on substrate binding. The comparison of this structure with the inactive turkey delta I crystallin reveals that the conformation of domain 1 is crucial for substrate affinity and that the delta I protein is almost certainly inactive because it can no longer bind the substrate.

PubMed: 10029536
DOI: 10.1021/bi982149h

実験手法

X-RAY DIFFRACTION (2.3 Å)