Proceedings of the Korean Society for Bioinformatics Conference (한국생물정보학회:학술대회논문집)
- 2003.10a
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- Pages.277-287
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- 2003
Homology modeling of the structure of tobacco acetolactate synthase and examination of the model by site-directed mutagenesis
- Le, Dung Tien (School of Life Sciences, Chungbuk National University) ;
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Yoon, Moon-Young
(Department of Chemistry, Hanyang University) ;
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Kim, Young-Tae
(Department of Microbiology, Pukyong National University) ;
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Choi, Jung-Do
(School of Life Sciences, Chungbuk National University)
- Published : 2003.10.31
Abstract
Acetolactate synthase (ALS, EC 4.1.3.18; also referred to as acetohydroxy acid synthase) catalyzes the first common step in the biosynthesis of valine, leucine, and isoleucine in microorganisms and plants. Recently X-ray structure of yeast ALS was available. Pair-wise alignment of yeast and tobacco ALS sequences revealed 63% sequence similarity. Using Deep View and automatic modeling on Swiss model server, we have generated reliable models of tobacco ALS based on yeast ALS template with a calculated pair-wise RMSD of 0.86 Angstrom. Functional roles of four residues located on the subunit interface (H142, El43, M350, and R376) were examined by site-directed mutagenesis. Seven mutants were generated and purified, of which three mutants (H142T, M350V, and R376F) were found to be inactivated under various assay conditions. The H142k mutant showed moderately altered kinetic properties. The E143A mutant increased 10-fold in K
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