Summary:
"DNA-binding protein under anaerobic conditions," Dan [1], formerly TtdR or YgiP, is an LysR-type transcriptional regulator for L-tartrate fermentation. Dan belongs to the same family of growth phase-specific nucleoid proteins as Fis, Dps, HU, IHF, and H-NS [1]. More specifically, Dan belongs to the group II nucleoid proteins, which include Fis, Rob (CbpB), CbpA, and IciA and show irregular distribution within the nucleoid [1]. Dan may have a functional dichotomy, controlling both the structure and function of the nucleoid [1].
In the presence of L- and meso-tartrate, Dan stimulates expression of the divergently transcribed ttdABT operon, encoding L-tartrate dehydratase and the L-tartrate:succinate antiporter [2, 4].
The ttd pathway for L-tartate fermentation and the dcu pathway for general C4-dicarboxylate metabolism interact at the regulatory level [2].
Expression of
ttdR (
dan gene) is positively autoregulated in response to L-tartrate
[2, 4] and activated by the two-component system DcuSR in the presence of L-tartrate,
meso-tartrate, D-malate or fumarate
[2].
ttdR (
dan gene) is repressed by FNR and the nitrate and nitrite two-component systems NarXL and NarPQ
[2].
In an electrophoretic mobility shift assay it was shown that Dan binds to the
ttdA-ttdR intergenic region
[2].
Based on genomic SELEX analysis, of a total of 688 Dan-binding sites, 504 were located within intergenic noncoding regions and 184 were within coding regions
[1].
Dan is a DNA-binding protein with recognition preference for the GTTNATT sequence. This motif suggests a role for Dan in resistance to a metal, as with Dps against iron
[1]. Dan contains two sets of Cys-Cys pairs: one consisting of Cys170 and Cys193, and other of Cys288 and Cys296
[1].
Dan is highly expressed in cells grown under hypoxic or anaerobic conditions, and it plays a role in local folding of DNA
[1].
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