Cloning and Characterization of Acetohydroxyacid Synthase from Bacillus stearothermophilus

Five genes from the ilv-leu operon from Bacillus stearothermophilus have been sequenced. Acetohydroxyacid synthase (AHAS) and its subunits were separately cloned, purified, and characterized. This thermophilic enzyme resembles AHAS III of Escherichia coli, and regulatory subunits of AHAS III complement the catalytic subunit of the AHAS of B. stearothermophilus, suggesting that AHAS III is functionally and evolutionally related to the single AHAS of gram-positive bacteria