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2j0p
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Bacteria rely on their environment and/or host to acquire iron and have | + | 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== | ==About this Structure== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Yersinia enterocolitica]] | [[Category: Yersinia enterocolitica]] | ||
| - | [[Category: Barker, P | + | [[Category: Barker, P D.]] |
[[Category: Paoli, M.]] | [[Category: Paoli, M.]] | ||
[[Category: Schneider, S.]] | [[Category: Schneider, S.]] | ||
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[[Category: transport]] | [[Category: transport]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:58:06 2008'' |
Revision as of 15:58, 21 February 2008
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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
2J0P is a Single protein structure of sequence from Yersinia enterocolitica with , , and as ligands. Known structural/functional Site: . 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 Thu Feb 21 17:58:06 2008
Categories: Single protein | Yersinia enterocolitica | Barker, P D. | Paoli, M. | Schneider, S. | Sharp, K. | 12P | HEM | MLI | PEG | Conformational changes | Haem | Haem-binding protein | Ion transport | Iron | Iron transport | Proteobacteria | Transport
