Spindle poles (green) separate during S-phase distress in cells that cannot link duplicated centromeres to microtubules from both poles.
Spindle assembly and DNA replication occur simultaneously in budding yeast. So if DNA synthesis stalls—from a lack of nucleotides, for instance—yeast cells must prevent untimely spindle elongation until replication resumes. This S-phase checkpoint is controlled by the kinase Rad53, which both maintains replication forks during stalls and prevents spindle elongation. The new results suggest these processes may be linked mechanistically.
By maintaining fork integrity as nucleotides begin to run out, Rad53 may ensure that at least some centromeres are replicated (budding yeast centromeres are copied from early-firing origins) even...
