title: Displacement of the canonical single-stranded DNA-binding protein in the Thermoproteales.
abstract: ssDNA-binding proteins (SSBs) based on the oligonucleotide-binding fold are considered ubiquitous in nature and play a central role in many DNA transactions including replication, recombination, and repair. We demonstrate that the Thermoproteales, a clade of hyperthermophilic Crenarchaea, lack a canonical SSB. Instead, they encode a distinct ssDNA-binding protein that we term "ThermoDBP," exemplified by the protein Ttx1576 from Thermoproteus tenax. ThermoDBP binds specifically to ssDNA with low sequence specificity. The crystal structure of Ttx1576 reveals a unique fold and a mechanism for ssDNA binding, consisting of an extended cleft lined with hydrophobic phenylalanine residues and flanked by basic amino acids. Two ssDNA-binding domains are linked by a coiled-coil leucine zipper. ThermoDBP appears to have displaced the canonical SSB during the diversification of the Thermoproteales, a highly unusual example of the loss of a "ubiquitous" protein during evolution.
authors: Biomedical Sciences Research Complex, University of St Andrews, Fife KY16 9ST, United Kingdom.
authors: Sonia
authors: S
authors: Paytubi
authors: Stephen A
authors: SA
authors: McMahon
authors: Shirley
authors: S
authors: Graham
authors: Huanting
authors: H
authors: Liu
authors: Catherine H
authors: CH
authors: Botting
authors: Kira S
authors: KS
authors: Makarova
authors: Eugene V
authors: EV
authors: Koonin
authors: James H
authors: JH
authors: Naismith
authors: Malcolm F
authors: MF
authors: White
mesh_terms: D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D019619:Thermoproteales / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins