View source for 1yi1

[[Image:1yi1.gif|left|200px]]<br /><applet load="1yi1" size="350" color="white" frame="true" align="right" spinBox="true" 
caption="1yi1, resolution 2.90&Aring;" />
'''Crystal structure of Arabidopsis thaliana Acetohydroxyacid synthase In Complex With A Sulfonylurea Herbicide, Tribenuron methyl'''<br />

==Overview==
The sulfonylureas and imidazolinones are potent commercial herbicide families. They are among the most popular choices for farmers worldwide, because they are nontoxic to animals and highly selective. These herbicides inhibit branched-chain amino acid biosynthesis in plants by targeting acetohydroxyacid synthase (AHAS, EC 2.2.1.6). This report describes the 3D structure of Arabidopsis thaliana AHAS in complex with five sulfonylureas (to 2.5 A resolution) and with the imidazolinone, imazaquin (IQ; 2.8 A). Neither class of molecule has a structure that mimics the substrates for the enzyme, but both inhibit by blocking a channel through which access to the active site is gained. The sulfonylureas approach within 5 A of the catalytic center, which is the C2 atom of the cofactor thiamin diphosphate, whereas IQ is at least 7 A from this atom. Ten of the amino acid residues that bind the sulfonylureas also bind IQ. Six additional residues interact only with the sulfonylureas, whereas there are two residues that bind IQ but not the sulfonylureas. Thus, the two classes of inhibitor occupy partially overlapping sites but adopt different modes of binding. The increasing emergence of resistant weeds due to the appearance of mutations that interfere with the inhibition of AHAS is now a worldwide problem. The structures described here provide a rational molecular basis for understanding these mutations, thus allowing more sophisticated AHAS inhibitors to be developed. There is no previously described structure for any plant protein in complex with a commercial herbicide.

==About this Structure==
1YI1 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Arabidopsis_thaliana Arabidopsis thaliana] with <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=1TB:'>1TB</scene>, <scene name='pdbligand=NHE:'>NHE</scene>, <scene name='pdbligand=P22:'>P22</scene> and <scene name='pdbligand=FAD:'>FAD</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Acetolactate_synthase Acetolactate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.2.1.6 2.2.1.6] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1YI1 OCA]. 

==Reference==
Herbicide-binding sites revealed in the structure of plant acetohydroxyacid synthase., McCourt JA, Pang SS, King-Scott J, Guddat LW, Duggleby RG, Proc Natl Acad Sci U S A. 2006 Jan 17;103(3):569-73. Epub 2006 Jan 10. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16407096 16407096]
[[Category: Acetolactate synthase]]
[[Category: Arabidopsis thaliana]]
[[Category: Single protein]]
[[Category: Duggleby, R G.]]
[[Category: Guddat, L W.]]
[[Category: King-Scott, J.]]
[[Category: McCourt, J A.]]
[[Category: Pang, S S.]]
[[Category: 1TB]]
[[Category: FAD]]
[[Category: MG]]
[[Category: NHE]]
[[Category: P22]]
[[Category: acetohydroxyacid synthase]]
[[Category: acetolactate synthase]]
[[Category: ches]]
[[Category: cysteine-s-dioxide]]
[[Category: fad]]
[[Category: herbicide]]
[[Category: inhibitor]]
[[Category: sulfonylurea]]
[[Category: thiamin diphosphate]]
[[Category: tribenuron methyl]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:05:30 2008''