1fi1
From Proteopedia
(New page: 200px<br /><applet load="1fi1" size="450" color="white" frame="true" align="right" spinBox="true" caption="1fi1, resolution 2.90Å" /> '''FhuA in complex with...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:1fi1.gif|left|200px]]<br /><applet load="1fi1" size=" | + | [[Image:1fi1.gif|left|200px]]<br /><applet load="1fi1" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1fi1, resolution 2.90Å" /> | caption="1fi1, resolution 2.90Å" /> | ||
'''FhuA in complex with lipopolysaccharide and rifamycin CGP4832'''<br /> | '''FhuA in complex with lipopolysaccharide and rifamycin CGP4832'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: FhuA, an integral membrane protein of Escherichia coli, actively transports ferrichrome and the structurally related antibiotic | + | BACKGROUND: FhuA, an integral membrane protein of Escherichia coli, actively transports ferrichrome and the structurally related antibiotic albomycin across the outer membrane. The transport is coupled to the proton motive force, which energizes FhuA through the inner-membrane protein TonB. FhuA also transports the semisynthetic rifamycin derivative CGP 4832, although the chemical structure of this antibiotic differs markedly from that of ferric hydroxamates. RESULTS: X-ray crystallography revealed that rifamycin CGP 4832 occupies the same ligand binding site as ferrichrome and albomycin, thus demonstrating a surprising lack of selectivity. However, the binding of rifamycin CGP 4832 is deviant from the complexes of FhuA with hydroxamate-type ligands in that it does not result in the unwinding of the switch helix but only in its destabilization, as reflected by increased B factors. Unwinding of the switch helix is proposed to be required for efficient binding of TonB to FhuA and for coupling the proton motive force of the cytoplasmic membrane with energy-dependent ligand transport. The transport data from cells expressing mutant FhuA proteins indicated conserved structural and mechanistic requirements for the transport of both types of compounds. CONCLUSIONS: We conclude that the binding of rifamycin CGP 4832 destabilizes the switch helix and promotes the formation of a transport-competent FhuA-TonB complex, albeit with lower efficiency than ferrichrome. Active transport of this rifamycin derivative explains the 200-fold increase in potency as compared to rifamycin, which is not a FhuA-specific ligand and permeates across the cell envelope by passive diffusion only. |
==About this Structure== | ==About this Structure== | ||
| - | 1FI1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with PO4, NI, NA, MG, FTT, DPO, RIF and DDQ as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 1FI1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=NI:'>NI</scene>, <scene name='pdbligand=NA:'>NA</scene>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=FTT:'>FTT</scene>, <scene name='pdbligand=DPO:'>DPO</scene>, <scene name='pdbligand=RIF:'>RIF</scene> and <scene name='pdbligand=DDQ:'>DDQ</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FI1 OCA]. |
==Reference== | ==Reference== | ||
| Line 15: | Line 15: | ||
[[Category: Boes, C.]] | [[Category: Boes, C.]] | ||
[[Category: Braun, V.]] | [[Category: Braun, V.]] | ||
| - | [[Category: Coulton, J | + | [[Category: Coulton, J W.]] |
[[Category: Diederichs, K.]] | [[Category: Diederichs, K.]] | ||
| - | [[Category: Ferguson, A | + | [[Category: Ferguson, A D.]] |
[[Category: Koedding, J.]] | [[Category: Koedding, J.]] | ||
[[Category: Walker, G.]] | [[Category: Walker, G.]] | ||
| Line 31: | Line 31: | ||
[[Category: outer membrane protein; tonb-dependent receptor; fhua; siderophore receptor; integral membrane protein; lipopolysaccharide; rifamycin cgp 4832; beta-barrel; antibiotic]] | [[Category: outer membrane protein; tonb-dependent receptor; fhua; siderophore receptor; integral membrane protein; lipopolysaccharide; rifamycin cgp 4832; beta-barrel; antibiotic]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:38:53 2008'' |
Revision as of 10:38, 21 February 2008
|
FhuA in complex with lipopolysaccharide and rifamycin CGP4832
Overview
BACKGROUND: FhuA, an integral membrane protein of Escherichia coli, actively transports ferrichrome and the structurally related antibiotic albomycin across the outer membrane. The transport is coupled to the proton motive force, which energizes FhuA through the inner-membrane protein TonB. FhuA also transports the semisynthetic rifamycin derivative CGP 4832, although the chemical structure of this antibiotic differs markedly from that of ferric hydroxamates. RESULTS: X-ray crystallography revealed that rifamycin CGP 4832 occupies the same ligand binding site as ferrichrome and albomycin, thus demonstrating a surprising lack of selectivity. However, the binding of rifamycin CGP 4832 is deviant from the complexes of FhuA with hydroxamate-type ligands in that it does not result in the unwinding of the switch helix but only in its destabilization, as reflected by increased B factors. Unwinding of the switch helix is proposed to be required for efficient binding of TonB to FhuA and for coupling the proton motive force of the cytoplasmic membrane with energy-dependent ligand transport. The transport data from cells expressing mutant FhuA proteins indicated conserved structural and mechanistic requirements for the transport of both types of compounds. CONCLUSIONS: We conclude that the binding of rifamycin CGP 4832 destabilizes the switch helix and promotes the formation of a transport-competent FhuA-TonB complex, albeit with lower efficiency than ferrichrome. Active transport of this rifamycin derivative explains the 200-fold increase in potency as compared to rifamycin, which is not a FhuA-specific ligand and permeates across the cell envelope by passive diffusion only.
About this Structure
1FI1 is a Single protein structure of sequence from Escherichia coli with , , , , , , and as ligands. Full crystallographic information is available from OCA.
Reference
Active transport of an antibiotic rifamycin derivative by the outer-membrane protein FhuA., Ferguson AD, Kodding J, Walker G, Bos C, Coulton JW, Diederichs K, Braun V, Welte W, Structure. 2001 Aug;9(8):707-16. PMID:11587645
Page seeded by OCA on Thu Feb 21 12:38:53 2008
Categories: Escherichia coli | Single protein | Boes, C. | Braun, V. | Coulton, J W. | Diederichs, K. | Ferguson, A D. | Koedding, J. | Walker, G. | Welte, W. | DDQ | DPO | FTT | MG | NA | NI | PO4 | RIF | Outer membrane protein; tonb-dependent receptor; fhua; siderophore receptor; integral membrane protein; lipopolysaccharide; rifamycin cgp 4832; beta-barrel; antibiotic
