Article

Biophysical analysis of Thermus aquaticus single-stranded DNA binding protein.

Institute for Biophysical Chemistry, Hannover Medical School, D-30625 Hanover, Germany.
Biophysical Journal (impact factor: 3.65). 04/2008; 94(6):2269-79. DOI:10.1529/biophysj.107.121533 pp.2269-79
Source: PubMed

ABSTRACT Due to their involvement in processes such as DNA replication, repair, and recombination, bacterial single-stranded DNA binding (SSB) proteins are essential for the survival of the bacterial cell. Whereas most bacterial SSB proteins form homotetramers in solution, dimeric SSB proteins were recently discovered in the Thermus/Deinococcus group. In this work we characterize the biophysical properties of the SSB protein from Thermus aquaticus (TaqSSB), which is structurally quite similar to the tetrameric SSB protein from Escherichia coli (EcoSSB). The binding of TaqSSB and EcoSSB to single-stranded nucleic acids was found to be very similar in affinity and kinetics. Mediated by its highly conserved C-terminal region, TaqSSB interacts with the chi-subunit of E. coli DNA polymerase III with an affinity that is similar to that of EcoSSB. Using analytical ultracentrifugation, we show that TaqSSB mutants are able to form tetramers in solution via arginine-mediated hydrogen-bond interactions that we identified in the crystal packing of wild-type TaqSSB. In EcoSSB, we identified a homologous arginine residue involved in the formation of higher aggregates and metastable highly cooperative single-stranded DNA binding under low salt conditions.

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    Natalie Naue, Roman Fedorov, Andreas Pich, Dietmar J Manstein, Ute Curth
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    Nucleic Acids Research 10/2010; 39(4):1398-407. · 8.03 Impact Factor
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    Sirine El Houry Mignan, Gregor Witte, Natalie Naue, Ute Curth
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    PLoS ONE 01/2011; 6(12):e27216. · 4.09 Impact Factor
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Keywords

arginine-mediated hydrogen-bond interactions
 
bacterial cell
 
bacterial single-stranded DNA binding
 
bacterial SSB proteins form homotetramers
 
conserved C-terminal region
 
dimeric SSB proteins
 
E. coli DNA polymerase III
 
EcoSSB
 
Escherichia coli
 
form tetramers
 
homologous arginine residue
 
low salt conditions
 
single-stranded nucleic acids
 
SSB protein
 
TaqSSB
 
TaqSSB interacts
 
TaqSSB mutants
 
tetrameric SSB protein
 
Thermus/Deinococcus group
 
wild-type TaqSSB