Molecular interplay between the DNA damage checkpoint kinase Mec1-Ddc2 and its activator Dpb11 on gapped DNA.

ABSTRACT: The eukaryotic DNA damage and replication stress checkpoint is an essential component of the DNA damage response and crucial for genome maintenance. In budding yeast, the apical kinase Mec1 (ATR ortholog), along with binding partner Ddc2 (ATRIP ortholog), senses persistent RPA-bound ssDNA in the cell. Mec1 is activated by interaction with a Mec1-activating protein. One such activator, Dpb11 (TopBP1 ortholog), is recruited to a 5' ss-dsDNA junction via the 9-1-1 checkpoint clamp. Due to their differential DNA binding preferences, it remains to be determined how Mec1 encounters its activators on damaged DNA. Using real-time single-molecule imaging of checkpoint proteins binding to dsDNA containing a long ssDNA gap, we show that, even in the absence of 9-1-1, Dpb11 binds to ssDNA and localize

SUBMITTER: Beckwitt EC 

PROVIDER: S-EPMC12676381 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature