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| | {{STRUCTURE_2q7a| PDB=2q7a | SCENE= }} | | {{STRUCTURE_2q7a| PDB=2q7a | SCENE= }} |
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| - | '''Crystal structure of the cell surface heme transfer protein Shp'''
| + | ===Crystal structure of the cell surface heme transfer protein Shp=== |
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| - | ==Overview==
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| - | 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.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_17920629}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 17920629 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_17920629}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Beta sandwich]] | | [[Category: Beta sandwich]] |
| | [[Category: Heme binding protein]] | | [[Category: Heme binding protein]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 14:28:25 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 06:04:55 2008'' |
Revision as of 03:05, 28 July 2008
Template:STRUCTURE 2q7a
Crystal structure of the cell surface heme transfer protein Shp
Template:ABSTRACT PUBMED 17920629
About this Structure
2Q7A is a Single protein structure of sequence from Streptococcus pyogenes. Full crystallographic information is available from OCA.
Reference
Bis-methionyl coordination in the crystal structure of the heme-binding domain of the streptococcal cell surface protein Shp., Aranda R 4th, Worley CE, Liu M, Bitto E, Cates MS, Olson JS, Lei B, Phillips GN Jr, J Mol Biol. 2007 Nov 23;374(2):374-83. Epub 2007 Aug 31. PMID:17920629
Page seeded by OCA on Mon Jul 28 06:04:55 2008
