DNA damage checkpoint activation affects peptidoglycan synthesis and late divisome components in Bacillus subtilis

Abstract

During normal DNA replication, all cells encounter damage to their genetic material. As a result, organisms have developed response pathways that provide time for the cell to complete DNA repair before cell division occurs. In Bacillus subtilis, it is well established that the SOS-induced cell division inhibitor YneA blocks cell division after genotoxic stress; however, it remains unclear how YneA enforces the checkpoint. Here, we identify mutations that disrupt YneA activity and mutations that are refractory to the YneA-induced checkpoint. We find that YneA C-terminal truncation mutants and point mutants in or near the LysM peptidoglycan binding domain render YneA incapable of checkpoint enforcement. In addition, we develop a genetic method which isolated mutations in the ftsW gene that completely bypassed checkpoint enforcement while also finding that YneA interacts with late divisome components FtsL, Pbp2b, and Pbp1. Characterization of an FtsW variant resulted in considerably shorter cells during the DNA damage response indicative of hyperactive initiation of cell division and bypass of the YneA-enforced DNA damage checkpoint.With our results, we present a model where YneA inhibits septal cell wall synthesis by binding peptidoglycan and interfering with interaction between late arriving divisome components causing DNA damage checkpoint activation.

DNA damage-induced block of sporulation in Streptomyces venezuelae involves downregulation of ssgB

“…For example, in Escherichia coli , activation of the SOS regulon includes the synthesis of SulA, which inhibits the polymerization of FtsZ, a GTPase that is essential for cell division in most bacteria [5]. Functionally distinct cell division inhibitors have been identified in Bacillus subtilis (YneA) [6–8], Corynebacterium glutamicum (DivS) [9], Caulobacter crescentus (SidA and DidA) [10, 11], Mycobacterium tuberculosis (ChiZ) [12] and Staphylococcus aureus (SosA) [13]. Some of these inhibitors interact directly or indirectly with components of the cell division or septum biosynthesis machinery, highlighting the fact that controlling cell division during the recovery from DNA damage is not limited to one protein target.…”

Genome-Wide Identification of the LexA-Mediated DNA Damage Response in Streptomyces venezuelae

“…Given the importance of recA in genome maintenance ( 28 ), it is likely that the observed phenotypic defects in the recA mutant are a direct consequence of genome instability, which could result in a large deletion in the chromosomal arms or defective chromosome segregation ( 8 , 29 ). Furthermore, in the lexA null mutant, permanent induction of the SOS response may result in the activation of a cell cycle checkpoint that suppresses sporulation, analogous to the SOS-dependent cell division inhibitors identified in diverse bacteria ( 30 – 33 ). Notably, Streptomyces lack clear homologs of these known cell division regulators, indicating the presence of a yet unidentified mechanism involved in coordinating DNA damage repair and cell division.…”

Genome-wide peptidoglycan profiling of Vibrio cholerae

“…For instance, almost 98% of the mutants of the V. cholerae transposon library present a statistically significant alteration of their PG profile (deviate at least 1SD from the average), and more than the 50% of the mutants presented a variation higher than 2SD of the average of the whole library for at least one muropeptide or a PG-feature) that included loci from all COG categories. These results are in agreement with studies that linked the cell wall with seemingly unrelated pathways/processes (e.g.,(Bancroft et al, 2020; Campbell et al, 2021; Masser et al, 2021)). Conversely, certain mutants in cell wall-annotated genes did not show an altered PG profile suggesting the existence of functional redundancies or condition-specific activities.…”