Ortholog of BRCA2-interacting protein BCCIP controls morphogenetic responses during DNA replication stress in...

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• BRCA2 is a tumor suppressor essential for DNA repair via homologous recombination, regulated by interacting proteins.
• BCCIP, a BRCA2-interacting protein, is implicated in regulating homologous recombination in mammalian cells.
• The function of the Ustilago maydis BCCIP ortholog, Bcp1, in DNA repair and recombination is largely unknown.

Purpose of the Study:

• To investigate the role of the Ustilago maydis Bcp1 protein in DNA repair and homologous recombination.
• To determine if Bcp1 interacts with the BRCA2-related protein Brh2 in U. maydis.
• To assess the impact of Bcp1 deletion on cell growth, DNA replication, and response to DNA replication stress.

Main Methods:

• Yeast two-hybrid assays to test for Bcp1-Brh2 interaction.
• Gene deletion to create Bcp1-deficient mutants.
• Phenotypic analysis including growth rates, cell cycle progression (S phase), hydroxyurea sensitivity, and DNA repair assays.
• Microscopy to assess cell morphology under replication stress.

Main Results:

• Bcp1 binds to the C-terminal region of Brh2, consistent with mammalian BCCIP-BRCA2 interactions.
• Bcp1 deletion mutants exhibit slow growth, S phase delays, and hydroxyurea sensitivity.
• Despite these sensitivities, Bcp1-deficient cells show normal DNA repair and homologous recombination.
• Absence of Bcp1 impairs the ability of cells to maintain normal morphology under DNA replication stress.

Conclusions:

• Bcp1 interacts with Brh2 and plays a role in DNA replication stress response in U. maydis.
• While not essential for core DNA repair or recombination, Bcp1 is vital for coordinating cell morphogenesis with DNA processing during replication.
• These findings suggest a conserved regulatory role for BCCIP orthologs in linking DNA metabolism with cellular integrity.