Publication Abstract from PubMed
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.
Displacement of the canonical single-stranded DNA-binding protein in the Thermoproteales.,Paytubi S, McMahon SA, Graham S, Liu H, Botting CH, Makarova KS, Koonin EV, Naismith JH, White MF Proc Natl Acad Sci U S A. 2011 Nov 21. PMID:22106294[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
