A dimeric mutant of the homotetrameric single-stranded DNA binding protein from Escherichia coli.
A single amino acid substitution (Y78R) at the dimer-dimer interface of homotetrameric single stranded DNA binding protein from E. coli (EcoSSB) renders the protein a stable dimer. This dimer can bind single-stranded DNA albeit with greatly reduced affinity. In vivo this dimeric SSB cannot replace homotetrameric EcoSSB. Amino acid changes at the rim of the dimer-dimer interface nearby (Q76K, Q76E) show an electrostatic interaction between a charged amino acid at position 76 and bound nucleic acid. In conclusion, nucleic acid binding to homotetrameric SSB must take place across both dimers to achieve functionally correct binding.
Landwehr
Marco
M
Biophysical Chemistry, Medical School Hannover, Germany.
Curth
Ute
U
Urbanke
Claus
C
D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D019791:Guanidine / Q000737:chemistry; D008958:Models, Molecular; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D011072:Poly U / Q000378:metabolism; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D014461:Ultracentrifugation
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D011072:Poly U; D019791:Guanidine