2j0r
From Proteopedia
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'''STRUCTURE OF THE HAEM-CHAPERONE PROTEOBACTERIA-PROTEIN HEMS''' | '''STRUCTURE OF THE HAEM-CHAPERONE PROTEOBACTERIA-PROTEIN HEMS''' | ||
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[[Category: Schneider, S.]] | [[Category: Schneider, S.]] | ||
[[Category: Sharp, K.]] | [[Category: Sharp, K.]] | ||
| - | [[Category: | + | [[Category: Conformational change]] |
| - | [[Category: | + | [[Category: Haem]] |
| - | [[Category: | + | [[Category: Haem-binding protein]] |
| - | [[Category: | + | [[Category: Ion transport]] |
| - | [[Category: | + | [[Category: Iron]] |
| - | [[Category: | + | [[Category: Iron transport]] |
| - | [[Category: | + | [[Category: Proteobacteria]] |
| - | [[Category: | + | [[Category: Transport]] |
| - | [[Category: | + | [[Category: Transport protein]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 08:10:55 2008'' | |
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Revision as of 05:10, 4 May 2008
STRUCTURE OF THE HAEM-CHAPERONE PROTEOBACTERIA-PROTEIN HEMS
Overview
Bacteria rely on their environment and/or host to acquire iron and have evolved specialized systems to sequester and transport heme. The heme uptake system HemRSTUV is common to proteobacteria, and a major challenge is to understand the molecular mechanism of heme binding and transfer between the protein molecules that underlie this heme transport relay process. In the Gram-negative pathogen Yersinia enterocolitica, the HemRSTUV system culminates with the cytoplasmic recipient HemS, which stores and delivers heme for cellular needs. HemS belongs to a family of proteins essential and unique to proteobacteria. Here we report on the binding mechanism of HemS based on structural data from its apo- and ligand-loaded forms. This heme carrier protein associates with its cargo through a novel, partly preformed binding pocket, formed between a large beta-sheet dome and a three-helix subdomain. In addition to a histidine interacting with the iron, the complex is stabilized by a distal non-coordinating arginine that packs along the porphyrin plane and extensive electrostatic contacts that firmly anchor the heme propionate groups within the protein. Comparison of apo- and ligand-bound HemS crystal structures reveals striking conformational changes that underlie a "heme-induced fit" binding mechanism. Local shifts in amino acid positions combine with global, rigid body-like domain movements, and together, these bring about a switch from an open, apo-form to a closed, bound state. This is the first report in which both liganded and unliganded forms of a heme transport protein are described, thus providing penetrating insights into its mechanism of heme binding and release.
About this Structure
2J0R is a Single protein structure of sequence from Yersinia enterocolitica. Full crystallographic information is available from OCA.
Reference
An induced fit conformational change underlies the binding mechanism of the heme transport proteobacteria-protein HemS., Schneider S, Sharp KH, Barker PD, Paoli M, J Biol Chem. 2006 Oct 27;281(43):32606-10. Epub 2006 Aug 30. PMID:16943192 Page seeded by OCA on Sun May 4 08:10:55 2008
