2Q7A

Crystal structure of the cell surface heme transfer protein Shp

2Q7A の概要

• エントリーDOI: 10.2210/pdb2q7a/pdb
• 分子名称: Cell surface heme-binding protein, PROTOPORPHYRIN IX CONTAINING FE, GLYCEROL, ... (4 entities in total)
• 機能のキーワード: beta sandwich, heme binding protein
• 由来する生物種: Streptococcus pyogenes
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 36533.97

構造登録者

Aranda IV, R.,Worley, C.E.,Bitto, E.,Phillips Jr., G.N. (登録日: 2007-06-06, 公開日: 2007-09-18, 最終更新日: 2024-02-21)

主引用文献

Aranda IV, R.,Worley, C.E.,Liu, M.,Bitto, E.,Cates, M.S.,Olson, J.S.,Lei, B.,Phillips Jr., G.N.
Bis-methionyl coordination in the crystal structure of the heme-binding domain of the streptococcal cell surface protein Shp.
J.Mol.Biol., 374:374-383, 2007

PubMed Abstract: Surface proteins Shr, Shp, and the ATP-binding cassette (ABC) transporter HtsABC are believed to make up the machinery for heme uptake in Streptococcus pyogenes. Shp transfers its heme to HtsA, the lipoprotein component of HtsABC, providing the only experimentally demonstrated example of direct heme transfer from a surface protein to an ABC transporter in Gram-positive bacteria. To understand the structural basis of heme transfer in this system, the heme-binding domain of Shp (Shp(180)) was crystallized, and its structure determined to a resolution of 2.1 A. Shp(180) exhibits an immunoglobulin-like beta-sandwich fold that has been recently found in other pathogenic bacterial cell surface heme-binding proteins, suggesting that the mechanisms of heme acquisition are conserved. Shp shows minimal amino acid sequence identity to these heme-binding proteins and the structure of Shp(180) reveals a unique heme-iron coordination with the axial ligands being two methionine residues from the same Shp molecule. A negative electrostatic surface of protein structure surrounding the heme pocket may serve as a docking interface for heme transfer from the more basic outer cell wall heme receptor protein Shr. The crystal structure of Shp(180) reveals two exogenous, weakly bound hemins, which form a large interface between the two Shp(180) molecules in the asymmetric unit. These "extra" hemins form a stacked pair with a structure similar to that observed previously for free hemin dimers in aqueous solution. The propionates of the protein-bound heme coordinate to the iron atoms of the exogenous hemin dimer, contributing to the stability of the protein interface. Gel filtration and analytical ultracentrifugation studies indicate that both full-length Shp and Shp(180) are monomeric in dilute aqueous solution.

PubMed: 17920629
DOI: 10.1016/j.jmb.2007.08.058

実験手法

X-RAY DIFFRACTION (2.1 Å)