The Escherichia coli transcription factor NikR is responsible for nickel-mediated repression of the nik operon. The crystal structure of NikR in complex with its operator sequence provided insight into the mechanistic details of nickel-activated NikR-DNA complex formation. The crystal structure revealed that the α3 helix and its preceding loop (residues 63-79) in two of the metal-binding domains—which become structurally ordered after high-affinity nickel binding—make non-specific contacts with the DNA phosphodiester backbone. The proposed mechanism of NikR binding to DNA suggests that the non-specific interactions between the DNA phosphodiester backbone and the positively-charged residues Lys64 and Arg65 anchor NikR to the DNA, thereby allowing the protein to initiate a one-dimensional search for its recognition sequence. The DNA-binding studies presented here strongly support an important role for Lys64 and Arg65 in NikR-DNA complex formation which is in agreement with the proposed model of NikR binding to DNA.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/32475 |
| Date | 20 July 2012 |
| Creators | Krecisz, Sandra |
| Contributors | Zamble, Deborah |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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