Displacement of the canonical single-stranded DNA-binding protein in the Thermoproteales
Abstract
Single-stranded DNA binding proteins (SSBs) based on the OB-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 protein Ttx1576 from Thermoproteus tenax. ThermoDBP binds specifically to ssDNA with low sequence specificity. The crystal structure of Ttx1576 reveals a unique fold and 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 where a “ubiquitous” protein has been lost in evolution.
Citation
Paytubi , S , McMahon , S , Graham , S , Liu , H , Botting , C H , Makarova , K S , Kroonin , E V , Naismith , J & White , M F 2012 , ' Displacement of the canonical single-stranded DNA-binding protein in the Thermoproteales ' , Proceedings of the National Academy of Sciences of the United States of America , vol. 109 , no. 7 , pp. E398-E405 . https://doi.org/10.1073/pnas.1113277108
Publication
Proceedings of the National Academy of Sciences of the United States of America
Status
Peer reviewed
ISSN
0027-8424Type
Journal article
Collections
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