Displacement of the canonical single-stranded DNA-binding protein in the Thermoproteales.
Proc Natl Acad Sci U S A
; 109(7): E398-405, 2012 Feb 14.
Article
em En
| MEDLINE
| ID: mdl-22106294
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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Thermoproteales
/
Proteínas de Ligação a DNA
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article