Structural insights into operator recognition by BioQ in the Mycobacterium smegmatis biotin synthesis pathway

Biochimica Et Biophysica Acta. General Subjects
Ling YanJin He

Abstract

Biotin is an essential cofactor in living organisms. The TetR family transcriptional regulator (TFTR) BioQ is the main regulator of biotin synthesis in Mycobacterium smegmatis. BioQ represses the expression of its target genes by binding to a conserved palindromic DNA sequence (the BioQ operator). However, the mechanism by which BioQ recognizes this DNA element has not yet been fully elucidated. We solved the crystal structures of the BioQ homodimer in its apo-form and in complex with its specific operator at 2.26 Å and 2.69 Å resolution, respectively. BioQ inserts the N-terminal recognition helix of each protomer into the corresponding major grooves of its operator and stabilizes the formation of the complex via electrostatic interactions and hydrogen bonding to induce conformational changes in both the DNA and BioQ. The DNA interface of BioQ is rich in positively charged residues, which help BioQ stabilize DNA binding. We elucidated the structural basis of DNA recognition by BioQ for the first time and identified the amino acid residues responsible for DNA binding via further site-directed mutagenesis. Our findings clearly elucidate the mechanism by which BioQ recognizes its operator in the biotin synthesis pathway and reveal...Continue Reading

Citations

Sep 10, 2020·Proceedings of the National Academy of Sciences of the United States of America·Zhe Hu, John E Cronan
Jan 12, 2021·FEMS Microbiology Reviews·Chaiyos Sirithanakorn, John E Cronan

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