Related Experiment Videos
Direct observation of three conformations of MutS protein regulated by adenine nucleotides
R Kato1, M Kataoka, H Kamikubo
1Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Japan.
Abstract:
Mismatched base-pairs, which are caused by either DNA replication errors, DNA damage or genetic recombination, are repaired by the mismatch-repair system. The MutS protein, a component of the mismatch-repair system, recognizes mismatched base-pairs in DNA, and its DNA-binding activity is affected by ATP and ADP. Here, we show that the MutS protein from Thermus thermophilus HB8 can have three different conformations in solution, based on direct observations made by small-angle X-ray scattering. The conformation of MutS in solution is drastically influenced by the presence of ADP and ATP; the ATP-bound form has the most compact conformation, the ADP-bound form the most stretched, and the nucleotide-free form has a conformation intermediate between the two. Based on these findings, we conclude that the DNA-binding activity of MutS may depend on conformational changes triggered by both the binding and hydrolysis of ATP.
Insights
The MutS protein
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- DNA repair mechanisms are essential for maintaining genomic stability.
- The mismatch-repair system corrects DNA replication errors and DNA damage.
- MutS protein is a key component of the mismatch-repair system, recognizing DNA mismatches.
Purpose of the Study:
- To investigate the conformational states of the MutS protein from Thermus thermophilus HB8 in solution.
- To determine how ATP and ADP binding affects MutS protein conformation and DNA-binding activity.
Main Methods:
- Small-angle X-ray scattering (SAXS) was used to observe MutS protein conformations in solution.
- The study analyzed MutS protein in nucleotide-free, ADP-bound, and ATP-bound states.
Main Results:
- MutS protein exhibits three distinct conformations in solution.
- Nucleotide binding significantly alters MutS conformation: ATP-bound is compact, ADP-bound is stretched.
- Nucleotide-free MutS adopts an intermediate conformation.
Conclusions:
- MutS protein conformation is dynamically regulated by ATP binding and hydrolysis.
- Conformational changes are likely crucial for MutS DNA-binding activity and mismatch repair function.