Structure analysis of PH1161 protein, a transcriptional activator TenA homologue from the hyperthermophilic archaeon Pyrococcus horikoshii

The crystal structure of the Bacillus subtilis TenA‐homologue protein PH1161 from the hyperthermophilic archaebacterium Pyrococcus horikoshii was determined. TenA is known to belong to a new family of activators that stimulate the production of extracellular proteases in B. subtilis . A sequence‐similarity search revealed that TenA‐homologue proteins are widespread in bacteria and archaea, suggesting that this family of proteins plays an essential role in these organisms. In the present study, the first three‐dimensional structure of a member of the TenA family of proteins was determined, unexpectedly revealing that the protein has a fold identical to that of haem oxygenase‐1. Analysis has also shown that the protein has a unique ligand‐binding pocket. Electron density of a bound ligand molecule was observed in this pocket. These results provide a valuable insight into the functional understanding of the TenA family of proteins.