Abstract
NMR studies have revealed the mechanism of a functional switch in the Escherichia coli Ada protein, which converts the DNA methyltransferase to a transcriptional regulator. The Ada protein acquires its ability to bind specific DNA sequences after an irreversible methyl transfer to its own cysteine residue (Cys69) from methyl-phosphotriesters within the alkylated DNA. NMR analysis have revealed that the segment from residues 102 to 123 forms a helix-turn-helix structure, and a site-directed mutagenesis study has identified the second helix to play a crucial role in specific recognition of DNA. NMR experiments on the methylated protein-DNA complex showed that although the major contacts are made by residues within the recognition helix, the S-methyl group at Cys69 come into direct contact with the cognate DNA. Therefore, the direct contact of this region after methylation is the “switch” which converts the Ada protein from a nonspecific DNA binding form to a transcription factor.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
