Related Experiment Videos
DNA lesion recognition by the bacterial repair enzyme MutM.
J Christopher Fromme1, Gregory L Verdine
1Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
The Journal of Biological Chemistry
|October 4, 2003
Summary
MutM, a bacterial DNA repair enzyme, recognizes the mutagenic 8-oxoguanine (oxoG) lesion by sensing its unique chemical properties. Its flexible structure allows it to bind oxoG and other DNA damage, highlighting its versatile repair function.
Area of Science:
- Molecular Biology
- Biochemistry
- DNA Repair Mechanisms
Background:
- MutM (also known as Fpg) is a crucial bacterial DNA glycosylase.
- It specifically removes the mutagenic 8-oxoguanine (oxoG) lesion from DNA.
- Understanding MutM's recognition mechanism is vital due to the abundance of normal guanine bases.
Purpose of the Study:
- To elucidate the structural basis of 8-oxoguanine recognition by MutM.
- To investigate how MutM distinguishes oxoG from undamaged guanine.
- To explore MutM's ability to recognize alternative DNA lesions.
Main Methods:
- X-ray crystallography of MutM in complex with oxoG-containing DNA.
- Structural analysis of MutM bound to DNA with dihydrouracil.
Main Results:
- The crystal structure reveals MutM binds oxoG in the syn glycosidic configuration.
- Recognition involves sensing the N7 atom's protonation state, differentiating oxoG from guanine.
- A flexible loop in MutM is key for lesion recognition and influences catalysis.
- MutM can also recognize alternative substrates like dihydrouracil.
Conclusions:
- MutM employs specific structural features and conformational flexibility for accurate DNA lesion recognition.
- The enzyme's mechanism allows for discrimination between damaged and normal bases.
- MutM exhibits versatility in repairing various types of DNA damage.