Homology modeling of the structure of bacterial acetohydroxy acid synthase and examination of the active site by site-directed mutagenesis

Biochemistry
M IbdahDavid M Chipman

Abstract

Acetohydroxy acid synthase (AHAS, EC 4.1.3.18) catalyzes the thiamin pyrophosphate (TPP)-dependent decarboxylation of pyruvate and condensation of the resulting two-carbon moiety with a second alpha-keto acid. It belongs to a family of homologous, TPP-dependent enzymes which catalyze different reactions which start from decarboxylation of alpha-keto acids. A model for the structure of Escherichia coli AHAS isozyme II, based on its homology with pyruvate oxidase and experimental testing of the model by site-directed mutagenesis, has been used here to study how AHAS controls the chemical fate of a decarboxylated keto acid. Because of the potential conformational freedom of the reacting substrates, residues interacting with the substrate could not be identified directly from the model of AHAS. Three residues were considered as candidates for involvement in the recognition of alpha-ketobutyrate, as the amino acids at these sites in a unique low-specificity AHAS are different from those in typical AHASs, which are highly specific for reaction with alpha-ketobutyrate as second substrate, in preference to pyruvate. These residues were altered in AHAS II by site-directed mutagenesis. Replacement of Trp464 lowers the specificity by at l...Continue Reading

References

Sep 1, 1992·Journal of Bacteriology·O WeinstockZ Barak
Sep 1, 1993·Journal of Bacteriology·C SellaD M Chipman

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Citations

Jul 10, 1998·Biochimica Et Biophysica Acta·D ChipmanJ V Schloss
Dec 6, 2000·The Biochemical Journal·Y Y Chang, J E Cronan
Mar 7, 2001·Applied and Environmental Microbiology·L SunM Q Xu
Jun 5, 2002·Annual Review of Biochemistry·Xuemei M He, Hung-Wen Liu
Jan 11, 2005·Proceedings of the National Academy of Sciences of the United States of America·Kai TittmannDavid M Chipman
May 18, 2005·Journal of Enzyme Inhibition and Medicinal Chemistry·Ronald G Duggleby
Feb 1, 2008·Plant Physiology and Biochemistry : PPB·Ronald G DugglebyLuke W Guddat
Jul 31, 2003·Biotechnology and Bioengineering·Stanislav EngelDavid M Chipman
Aug 28, 2007·Archives of Biochemistry and Biophysics·Kyoung-Jae ChoiMoon-Young Yoon
Apr 15, 2004·Biochemical and Biophysical Research Communications·Dung Tien LeJung-Do Choi
Dec 6, 2005·Biochimica Et Biophysica Acta·Valerie VinogradovDavid M Chipman
Aug 2, 2005·Current Opinion in Chemical Biology·David M ChipmanKai Tittmann
May 18, 2005·Trends in Biochemical Sciences·Jennifer A McCourt, Ronald G Duggleby
Aug 13, 2013·Enzyme and Microbial Technology·Irshad Ahmed BaigMoon-Young Yoon
Sep 1, 2016·Applied Microbiology and Biotechnology·Yadi LiuXiaoyuan Wang
Nov 1, 2015·Environmental Science and Pollution Research International·Ines PetricFabrice Martin-Laurent
Feb 20, 2020·International Journal of Molecular Sciences·Jun FangXiao Wang
Dec 24, 2002·The Journal of Biological Chemistry·Siew Siew PangRonald G Duggleby
Mar 21, 2002·Journal of Molecular Biology·Siew Siew PangLuke W Guddat
May 16, 2002·Plant Physiology·Miri LapidotMichal Shapira

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