The structure of a bacterial DUF199/WhiA protein: domestication of an invasive endonuclease.

Publication Type:

Journal Article

Source:

Structure (London, England : 1993), Volume 17, Issue 10, p.1368-76 (2009)

Keywords:

2009, Amino Acid Sequence, Bacterial Proteins, Basic Sciences Division, Endonucleases, Helix-Turn-Helix Motifs, Models, Molecular, Molecular Sequence Data, Protein Conformation, Spores, Bacterial, Thermotoga maritima

Abstract:

Proteins of the DUF199 family, present in all Gram-positive bacteria and best characterized by the WhiA sporulation control factor in Streptomyces coelicolor, are thought to act as genetic regulators. The crystal structure of the DUF199/WhiA protein from Thermatoga maritima demonstrates that these proteins possess a bipartite structure, in which a degenerate N-terminal LAGLIDADG homing endonuclease (LHE) scaffold is tethered to a C-terminal helix-turn-helix (HTH) domain. The LHE domain has lost those residues critical for metal binding and catalysis, and also displays an extensively altered DNA-binding surface as compared with homing endonucleases. The HTH domain most closely resembles related regions of several bacterial sigma70 factors that bind the -35 regions of bacterial promoters. The structure illustrates how an invasive element might be transformed during evolution into a larger assemblage of protein folds that can participate in the regulation of a complex biological pathway.