Structure of Thermotoga maritima TM0439: implications for the mechanism of bacterial GntR transcription regulators with Zn2+-binding FCD domains.Zheng, M., Cooper, D.R., Grossoehme, N.E., Yu, M., Hung, L.W., Cieslik, M., Derewenda, U., Lesley, S.A., Wilson, I.A., Giedroc, D.P., Derewenda, Z.S.
(2009) Acta Crystallogr D Biol Crystallogr 65: 356-365
- PubMed: 19307717
- DOI: 10.1107/S0907444909004727
- Structures With Same Primary Citation
- PubMed Abstract:
The GntR superfamily of dimeric transcription factors, with more than 6200 members encoded in bacterial genomes, are characterized by N-terminal winged-helix DNA-binding domains and diverse C-terminal regulatory domains which provide a basis for the ...
The GntR superfamily of dimeric transcription factors, with more than 6200 members encoded in bacterial genomes, are characterized by N-terminal winged-helix DNA-binding domains and diverse C-terminal regulatory domains which provide a basis for the classification of the constituent families. The largest of these families, FadR, contains nearly 3000 proteins with all-alpha-helical regulatory domains classified into two related Pfam families: FadR_C and FCD. Only two crystal structures of FadR-family members, those of Escherichia coli FadR protein and LldR from Corynebacterium glutamicum, have been described to date in the literature. Here, the crystal structure of TM0439, a GntR regulator with an FCD domain found in the Thermotoga maritima genome, is described. The FCD domain is similar to that of the LldR regulator and contains a buried metal-binding site. Using atomic absorption spectroscopy and Trp fluorescence, it is shown that the recombinant protein contains bound Ni(2+) ions but that it is able to bind Zn(2+) with K(d) < 70 nM. It is concluded that Zn(2+) is the likely physiological metal and that it may perform either structural or regulatory roles or both. Finally, the TM0439 structure is compared with two other FadR-family structures recently deposited by structural genomics consortia. The results call for a revision in the classification of the FadR family of transcription factors.
Department of Molecular Physiology and Biological Physics, Integrated Center for Structure-Function Innovation, University of Virginia, Charlottesville, VA 22908-0736, USA.