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Publication Abstract from PubMed

In contrast to the majority of tetrameric SSB proteins, the recently discovered SSB proteins from the Thermus/Deinoccus group form dimers. We solved the crystal structures of the SSB protein from Thermus aquaticus (TaqSSB) and a deletion mutant of the protein and show the structure of their ssDNA binding domains to be similar to the structure of tetrameric SSBs. Two conformations accompanied by proline cis-trans isomerization are observed in the flexible C-terminal region. For the first time, we were able to trace 6 out of 10 amino acids at the C-terminus of an SSB protein. This highly conserved region is essential for interaction with other proteins and we show it to adopt an extended conformation devoid of secondary structure. A model for binding this region to the chi subunit of DNA polymerase III is proposed. It explains at a molecular level the reason for the ssb113 phenotype observed in Escherichia coli.

3D structure of Thermus aquaticus single-stranded DNA-binding protein gives insight into the functioning of SSB proteins.,Fedorov R, Witte G, Urbanke C, Manstein DJ, Curth U Nucleic Acids Res. 2006;34(22):6708-17. Epub 2006 Dec 5. PMID:17148487^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.