A network of allosterically coupled residues in the bacteriophage T4 Mre11-Rad50 complex

Area of Science:

• Molecular biology
• Biochemistry
• Genetics

Background:

• The Mre11-Rad50 (MR) protein complex is crucial for DNA double-strand break repair.
• Allosteric regulation and communication between nuclease and ATPase sites in MR are known but poorly understood.

Purpose of the Study:

• To investigate the allosteric regulation mechanisms within the Mre11-Rad50 complex.
• To identify residues involved in the communication between the nuclease and ATPase active sites.

Main Methods:

• Statistical coupling analysis of Mre11 and Rad50 sequences to predict coevolving residues.
• Double-mutant cycle analysis to test predicted allosteric coupling between nuclease and ATPase activities.

Main Results:

• Statistical coupling analysis predicted a sector of six coevolving residues potentially involved in allosteric coupling.
• Experimental results confirmed allosteric coupling between a tyrosine residue in Mre11 and distant Rad50 residues.
• A tyrosine residue near Mre11's active site is allosterically linked to Rad50 residues over 40 Å away.

Conclusions:

• The identified allosteric coupling between Mre11 and Rad50 residues likely underlies the reciprocal regulation of the complex's nuclease and ATPase activities.
• This finding provides insight into the intricate regulatory mechanisms governing DNA double-strand break repair.