Affiliation:
1. Institute for Advanced Studies in Biological Process Technology, University of Minnesota, St. Paul 55108.
Abstract
The structural gene coding for the lysine-sensitive aspartokinase II of the methylotrophic thermotolerant Bacillus sp. strain MGA3 was cloned from a genomic library by complementation of an Escherichia coli auxotrophic mutant lacking all three aspartokinase isozymes. The nucleotide sequence of the entire 2.2-kb PstI fragment was determined, and a single open reading frame coding for the aspartokinase II enzyme was found. Aspartokinase II was shown to be an alpha 2 beta 2 tetramer (M(r) 122,000) with the beta subunit (M(r) 18,000) encoded within the alpha subunit (M(r) 45,000) in the samea reading frame. The enzyme was purified, and the N-terminal sequences of the alpha and beta subunits were identical with those predicted from the gene sequences. The predicted amino acid sequence was 76% identical with the sequence of the Bacillus subtilis aspartokinase II. The transcription initiation site was located approximately 350 bp upstream of the translation start site, and putative promoter regions at -10 (TATGCT) and -35 (ATGACA) were identified. A 300-nucleotide intervening sequence between the transcription initiation and translational start sites suggests a possible attenuation mechanism for the regulation of transcription of this enzyme in the presence of lysine.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
23 articles.
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