Multiple mechanisms for overcoming lethal over‐initiation of DNA replication. Issue 4 (11th September 2022)

• Record Type: Journal Article
• Authors: Anderson, Mary E.; Smith, Janet L.; Grossman, Alan D.
• Is Part Of: Molecular microbiology. Volume 118:Issue 4(2022)
• Page Start: 426
• Page End: 442
• Publication Date: 2022-09-11
• Subjects: Bacillus subtilis -- DNA helicase -- DNA replication -- replication elongation -- replication initiation; Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.14976
• Languages: English
• ISSNs: 0950-382X

Abstract

Abstract: DNA replication is highly regulated and primarily controlled at the step of initiation. In bacteria, the replication initiator DnaA and the origin of replication oriC are the primary targets of regulation. Perturbations that increase or decrease replication initiation can cause a decrease in cell fitness. We found that multiple mechanisms, including an increase in replication elongation and a decrease in replication initiation, can compensate for lethal over‐initiation. We found that in Bacillus subtilis, under conditions of rapid growth, loss of yabA, a negative regulator of replication initiation, caused a synthetic lethal phenotype when combined with the dnaA1 mutation that also causes replication over‐initiation. We isolated several classes of suppressors that restored viability to dnaA1 ∆yabA double mutants. Some suppressors ( relA, nrdR ) stimulated replication elongation. Others ( dnaC, cshA ) caused a decrease in replication initiation. One class of suppressors decreased replication initiation in the dnaA1 ∆yabA mutant by causing a decrease in the amount of the replicative helicase, DnaC. We found that decreased levels of helicase in otherwise wild‐type cells were sufficient to decrease replication initiation during rapid growth, indicating that the replicative helicase is limiting for replication initiation. Our results highlight the multiple mechanisms cells use to regulate DNA replication. Abstract : DNA replication is highly regulated and coordinated with several cellular processes, including growth. We found that when combined, two Bacillus subtilis mutations that cause replication over‐initiation are synthetic lethal, cause severe replication over‐initiation, replication fork collapse, and cell death. We found that this synthetic lethal phenotype can be suppressed by either decreasing replication initiation or stimulating replication elongation, thereby preventing replication fork collapse, and highlighting the multiple mechanisms cells can use to modulate DNA replication.