Crystal Structure of the Archaeal Heat Shock Regulator from Pyrococcus furiosus: A Molecular Chimera Representing Eukaryal and Bacterial Features

• Published in: Journal of molecular biology 2007-06, Vol.369 (2), p.474-488
• Main Authors: Liu, Wei, Vierke, Gudrun, Wenke, Ann-Kathrin, Thomm, Michael, Ladenstein, Rudolf
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Archaea; Archaeal Proteins - chemistry; Archaeal Proteins - genetics; Archaeal Proteins - metabolism; Bacteria; Base Sequence; Crystallography, X-Ray; Dimerization; Evolution, Molecular; Gene Expression Regulation, Archaeal; heat shock; Heat-Shock Proteins - chemistry; Heat-Shock Proteins - genetics; Heat-Shock Proteins - metabolism; Humans; Medicin och hälsovetenskap; Models, Molecular; Molecular Sequence Data; Phr; Point Mutation; Protein Structure, Quaternary; Protein Structure, Secondary; Protein Subunits - chemistry; Protein Subunits - genetics; Protein Subunits - metabolism; Pyrococcus furiosus; Pyrococcus furiosus - chemistry; Pyrococcus furiosus - genetics; Sequence Alignment; Static Electricity; transcriptional regulation; winged helix
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2007.03.044

We report here the crystal structure of a protein from Pyrococcus furiosus (Phr) that represents the first characterized heat shock transcription factor in archaea. Phr specifically represses the expression of heat shock genes at physiological temperature in vitro and in vivo but is released from the promoters upon heat shock response. Structure analysis revealed a stable homodimer, each subunit consisting of an N-terminal winged helix DNA-binding domain (wH-DBD) and a C-terminal antiparallel coiled coil helical domain. The overall structure shows as a molecular chimera with significant folding similarity of its DBD to the bacterial SmtB/ArsR family, while its C-terminal part was found to be a remote homologue of the eukaryotic BAG domain. The dimeric protein recognizes a palindromic DNA sequence. Molecular docking and mutational analyses suggested a novel binding mode in which the major specific contacts occur at the minor groove interacting with the strongly basic wing containing a cluster of three arginine residues.