Open AccessStructure of Thermotoga maritima TM0439: implications for the mechanism of bacterial GntR transcription regulators with Zn 2+ ‐binding FCD domains
Author(s) -
Zheng Meiying,
Cooper David R.,
Grossoehme Nickolas E.,
Yu Minmin,
Hung LiWei,
Cieslik Marcin,
Derewenda Urszula,
Lesley Scott A.,
Wilson Ian A.,
Giedroc David P.,
Derewenda Zygmunt S.
Publication year - 2009
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s0907444909004727
Subject(s) - thermotoga maritima , structural genomics , biology , genome , corynebacterium glutamicum , escherichia coli , recombinant dna , transcription (linguistics) , biochemistry , genetics , computational biology , gene , protein structure , linguistics , philosophy
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‐α‐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 n M . 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.