2now

An unusual twin-His arrangement in the pore of ammonia channels is essential for substrate conductance

spinqualitylabelsall models 2now, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2now is a 1 chain structure with sequence from "bacillus_coli"_migula_1895 "bacillus coli" migula 1895. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, GOL, SO4 Related: 1xqf, 1xqe, 1u7g, 2nmr, 2nop, 2npc, 2npd, 2npe, 2npg, 2npj, 2npk Gene: amtB ("Bacillus coli" Migula 1895) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [AMTB_ECOLI] Involved in the uptake of ammonia. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Amt proteins constitute a class of ubiquitous integral membrane proteins that mediate movement of ammonium across cell membranes. They are homotrimers, in which each subunit contains a narrow pore through which substrate transport occurs. Two conserved histidine residues in the pore have been proposed to be necessary for ammonia conductance. By analyzing 14 engineered polar and non-polar variants of these histidines, in Escherichia coli AmtB, we show that both histidines are absolutely required for optimum substrate conductance. Crystal structures of variants confirm that substitution of the histidine residues does not affect AmtB structure. In a subgroup of Amt proteins, found only in fungi, one of the histidines is replaced by glutamate. The equivalent substitution in E. coli AmtB is partially active, and the structure of this variant suggests that the glutamate side chain can make similar interactions to those made by histidine. An unusual twin-his arrangement in the pore of ammonia channels is essential for substrate conductance.,Javelle A, Lupo D, Zheng L, Li XD, Winkler FK, Merrick M J Biol Chem. 2006 Dec 22;281(51):39492-8. Epub 2006 Oct 12. PMID:17040913 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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