Rrm3 and Pif1 division of labor during replication through leading and lagging strand G-quadruplex

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Conserved Pif1 family DNA helicases unwind G-quadruplexes (G4s) to maintain genome stability.
• In yeast, Pif1 and Rrm3 suppress genomic instability at telomeres, centromeres, and tRNA genes.
• Pif1 resolves lagging strand G4s, but Rrm3's role at G4s and its cooperation with Pif1 are unclear.

Purpose of the Study:

• To investigate the real-time replication dynamics through G4 sequences.
• To elucidate the specific roles of Rrm3 and Pif1 in G4 replication.
• To understand the functional cooperation between Rrm3 and Pif1 at G4s.

Main Methods:

• Real-time monitoring of replication through G4 sequences in Saccharomyces cerevisiae.
• Analysis of Rrm3's catalytic activity and N-terminal unstructured region in G4 replication.
• Comparative study of Rrm3 and Pif1 functions at leading and lagging strand G4s.

Main Results:

• Rrm3 is essential for efficient replisome progression through leading strand G4s, but not lagging strand G4s.
• Rrm3's function at G4s depends on its catalytic activity and N-terminal unstructured region.
• Rrm3 and Pif1 demonstrate a division of labor for G4 replication.

Conclusions:

• Rrm3 and Pif1 have distinct, complementary roles in navigating G4 structures during DNA replication.
• This division of labor ensures robust replication fork progression through both leading and lagging strand G4s.
• Understanding these helicase functions is crucial for maintaining genome stability.