Oligomerization of a MutS mismatch repair protein from Thermus aquaticus.
The MutS DNA mismatch protein recognizes heteroduplex DNAs containing mispaired or unpaired bases. We have examined the oligomerization of a MutS protein from Thermus aquaticus that binds to heteroduplex DNAs at elevated temperatures. Analytical gel filtration, cross-linking of MutS protein with disuccinimidyl suberate, light scattering, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry establish that the Taq protein is largely a dimer in free solution. Analytical equilibrium sedimentation showed that the oligomerization of Taq MutS involves a dimer-tetramer equilibrium in which dimer predominates at concentrations below 10 microM. The DeltaG(0)(2-4) for the dimer to tetramer transition is approximately -6.9 +/- 0.1 kcal/mol of tetramer. Analytical gel filtration of native complexes and gel mobility shift assays of an maltose-binding protein-MutS fusion protein bound to a short, 37-base pair heteroduplex DNA reveal that the protein binds to DNA as a dimer with no change in oligomerization upon DNA binding.
Biswas
I
I
Genetics and Biochemistry Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Ban
C
C
Fleming
K G
KG
Qin
J
J
Lary
J W
JW
Yphantis
D A
DA
Yang
W
W
Hsieh
P
P
D000251:Adenosine Triphosphatases; D001426:Bacterial Proteins / Q000737:chemistry*; D020137:Base Pair Mismatch; D001483:Base Sequence; D001704:Biopolymers; D002850:Chromatography, Gel; D017931:DNA Primers; D004274:DNA, Recombinant / Q000378:metabolism; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D008027:Light; D051719:MutS DNA Mismatch-Binding Protein; D012542:Scattering, Radiation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013824:Thermus / Q000737:chemistry*
D001426:Bacterial Proteins; D001704:Biopolymers; D017931:DNA Primers; D004274:DNA, Recombinant; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli