2IBJ

Structure of House Fly Cytochrome B5

2IBJ の概要

• エントリーDOI: 10.2210/pdb2ibj/pdb
• 関連するPDBエントリー: 1CYO 1EUE 1ICC
• 分子名称: Cytochrome b5, MAGNESIUM ION, PROTOPORPHYRIN IX CONTAINING FE, ... (4 entities in total)
• 機能のキーワード: fly cytochrome b5, heme, electron transport
• 由来する生物種: Musca domestica (house fly)
• 細胞内の位置: Endoplasmic reticulum membrane ; Single-pass membrane protein ; Cytoplasmic side : P49096
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 10756.14

構造登録者

Terzyan, S.,Zhang, X.C.,Benson, D.R.,Wang, L. (登録日: 2006-09-11, 公開日: 2007-02-27, 最終更新日: 2023-08-30)

主引用文献

Wang, L.,Cowley, A.B.,Terzyan, S.,Zhang, X.,Benson, D.R.
Comparison of cytochromes b(5) from insects and vertebrates.
Proteins, 67:293-304, 2007

PubMed Abstract: We report a 1.55 A X-ray crystal structure of the heme-binding domain of cytochrome b(5) from Musca domestica (house fly; HF b(5)), and compare it with previously published structures of the heme-binding domains of bovine microsomal cytochrome b(5) (bMc b(5)) and rat outer mitochondrial membrane cytochrome b(5) (rOM b(5)). The structural comparison was done in the context of amino acid sequences of all known homologues of the proteins under study. We show that insect b(5)s contain an extended hydrophobic patch at the base of the heme binding pocket, similar to the one previously shown to stabilize mammalian OM b(5)s relative to their Mc counterparts. The hydrophobic patch in insects includes a residue with a bulky hydrophobic side chain at position 71 (Met). Replacing Met71 in HF b(5) with Ser, the corresponding residue in all known mammalian Mc b(5)s, is found to substantially destabilize the holoprotein. The destabilization is a consequence of two related factors: (1) a large decrease in apoprotein stability and (2) extension of conformational disruption in the apoprotein beyond the empty heme binding pocket (core 1) and into the heme-independent folding core (core 2). Analogous changes have previously been shown to accompany replacement of Leu71 in rOM b(5) with Ser. That the stabilizing role of Met71 in HF b(5) is manifested primarily in the apo state is highlighted by the fact that its crystallographic Calpha B factor is modestly larger than that of Ser71 in bMc b(5), indicating that it slightly destabilizes local polypeptide conformation when heme is in its binding pocket. Finally, we show that the final unit of secondary structure in the cytochrome b(5) heme-binding domain, a 3(10) helix known as alpha6, differs substantially in length and packing interactions not only for different protein isoforms but also for given isoforms from different species.

PubMed: 17299762
DOI: 10.1002/prot.21250

実験手法

X-RAY DIFFRACTION (1.55 Å)