Structural analysis of the transcriptional regulator homolog protein from Pyrococcus horikoshii OT3

Okada, Ui; Sakai, Naoki; Yao, Min; Watanabe, Nobuhisa; Tanaka, Isao

Structural analysis of the transcriptional regulator homolog protein from Pyrococcus horikoshii OT3

2006

Okada, Ui | Sakai, Naoki | Yao, Min | Watanabe, Nobuhisa | Tanaka, Isao

PH1061 is a hypothetical protein of 100 residues (11.4 kDa) from the 1hyperthermophilic archaebacterium, Pyrococcus horikoshii OT3 , and is conserved among many archaeal and bacterial organisms. Although the functions in these 2organisms are still unknown, a Pfam database search revealed that PH1061 has a helix-turn-helix (HTH) motif (“HTH_5 motif” in the Pfam database), and suggested that 3it is a DNA-binding protein, like members of the ArsR family . ArsR is a transcriptional repressor of the arsenic resistance operon in Escherichia coli and other members of this 4family involve zinc-sensing transcriptional repressors, such as CzrA from 5Staphylococcus aureus and SmtB from Synechococcus pcc7942. The primary sequence similarities to PH1061 are 20%, 21%, and 6.6% with ArsR, CzrA, and SmtB, respectively. There are 10 proteins with the HTH_5 motif in P. horikoshii, but none of their functions are known. For structure-based functional analysis, the three-dimensional structure of PH1061 was determined at a resolution of 2.05 A using the multi-wavelength anomalous diffraction (MAD) method.

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