The operon in encodes key enzymes for the biosynthesis of branched-chain amino acids (L-isoleucine, L-leucine, and L-valine). This operon has been studied for quite a long time, and it is assumed that three hairpin mRNA structures can be formed in its regulatory region; however, their functionality and role in the attenuation mechanism of the operon are not completely clear. In the present work, we performed a mutational analysis of mRNA secondary structures in the regulatory region of the operon, which allowed us to propose a model of the regulation of its transcription involving three mRNA hairpins that essentially act as a transcription terminator, an antiterminator, and an antiantiterminator.
View Article and Find Full Text PDFThe unicellular non-N(2)-fixing cyanobacterium Gloeocapsa alpicola CALU 743 contains a bidirectional hydrogenase. Parts of all structural genes, encoding the hydrogenase, were identified, cloned and sequenced. When comparing the sequences with analogous sequences from other cyanobacteria the highest similarity was observed with hox genes from Synechocystis sp.
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