The Rad50 coiled-coil domain is indispensable for Mre11 complex functions

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The Mre11 complex, comprising Mre11, Rad50, and Xrs2, is crucial for DNA damage response in Saccharomyces cerevisiae.
• This complex features globular DNA-binding domains, a Rad50 hook domain, and an extended Rad50 coiled-coil domain.

Purpose of the Study:

• To investigate the functional significance of the Rad50 coiled-coil domain in the Mre11 complex.
• To determine which Mre11 complex functions necessitate the full length of the coiled-coil domain.

Main Methods:

• Construction of rad50 alleles encoding truncations of the coiled-coil domain.
• Assessment of Mre11 complex functions including telomere maintenance, meiotic double-strand break (DSB) formation, homologous recombination, and nonhomologous end joining.

Main Results:

• Truncations of the Rad50 coiled-coil domain abolished telomere maintenance and meiotic DSB formation.
• Homologous recombination was severely impaired, indicating a need for long-range coiled-coil interactions.
• Nonhomologous end joining was also impaired by alterations in the coiled-coil and hook domains, suggesting their involvement.

Conclusions:

• The full length of the Rad50 coiled-coil domain is essential for specific Mre11 complex functions.
• The coiled coils of Rad50 integrate diverse functions of the Mre11 complex, including DNA repair pathways.
• The study provides the first evidence for the influence of coiled-coil and hook domains on nonhomologous end joining.