## 1 Introduction
While scanning the chromosome, DisA converts a pair of ATPs into the essential second messenger cyclic 3\({}^{\prime}\), 5\({}^{\prime}\)-diadenosine monophosphate (c-di-AMP) [19]. Paused DisA, however, drops the synthesis of c-di-AMP in response to replication perturbations, as those induced by methyl methane sulfonate (MMS) [20], to levels comparable to that in the absence of DisA [21]. DisA is composed of an N-terminal globular domain featuring diadenylate cyclase (DAC) activity, and a C-terminal RuvA-like HJ DNA-binding domain, separated by a central helical domain [22]. Octameric DisA, upon binding to a branched DNA structure, undergoes a conformational change that inhibits its c-di-AMP synthesis [22; 23; 24]. Low c-di-AMP levels indirectly increase (p)ppGpp synthesis [25], and (p)ppGpp blocks DNA replication by inhibiting DNA primase activity [26]. This DisA fail-safe mechanism of coordinating repair-by-recombination and replication is indirect, because DisA neither compromised PriA-dependent initiation of DNA replication nor affected replication elongation using an in vitro reconstituted replication assay [13]. DisA acts selectively at stalled forks, since \(\Delta\)_disA_ cells show a similar resistance to that of \(wt\) cells upon exposure to H\({}_{2}\)O\({}_{2}\) or nalidixic acid, which induce single-strand nicks or DSBs, respectively [21; 23]. Single-molecule studies revealed that DisA shows a dynamic movement in exponentially growing \(wt\) cells, but it becomes static when branched recombination intermediates accumulate, as in the absence of the RecU HJ resolvase or the RecG branch migration translocase [23]. The current model for DisA action is that this sensor protein may control the response to a replicative stress until the damage is removed, and balances the benefits and risks of fork remodeling [13; 17; 18; 27]. It is poorly understood whether functions that remodel branched DNA structures affect c-di-AMP synthesis. One may question which function(s) remodel a stalled replication fork in _B. subtilis_. In _E. coli_, stalled forks are processed by the RecA, RecG, RuvAB, or RecQ remodelers [28; 29; 30; 31; 32] or the ssDNA gap left by the skipped lesion is extended by RecJ and RecQ to facilitate RecA-mediated gap repair [7; 28; 29; 30; 31; 32]. Among the functions required for _B. subtilis_ spore survival upon DNA damage are RecA, RuvAB, RecU, RecG, and DisA, and genetic data have shown that the _disA_ gene is epistatic to _recA_, _ruvA_, _ruvB_, _recU_, and _recG_ genes upon exposure to ionizing radiation [12; 13]. This suggests that DisA acts with these proteins in common mechanisms to ensure the stability of the stalled forks and the maintenance of cell survival. Previous studies have explored how DisA could modulate RecA or RecGactivities [18; 27; 33], but the interplay between DisA and the resolvasome (RuvAB-RecU) is poorly understood. When a replicative stress occurs, the RuvAB levels increase as part of the SOS response, and the DisA and RecU pools increase as part of the cell envelope stress response [34; 35; 36], suggesting a temporal link between increasing levels of these proteins and a replication perturbation. RuvAB and RecU are the _B. subtilis_ counterpart of the _E. coli_ RuvABC (RuvABC\({}_{E\alpha}\)) resolvasome [37; 38; 39; 40; 41]. RuvA and RuvB are among the most ubiquitous bacterial proteins, whereas RecU is selectively found in bacteria of the Firmicutes and Tenericutes phyla. The RecU structure, which is unrelated to RuvC, shares homology to certain bacteriophages and archaeal HJ-resolving enzymes [42; 43]. The resolvasome might act at reversed forks (HJs) in response to a stalled fork and is crucial for the processing of double HJs during canonical DSB repair [5; 6; 7]. RuvA specifically binds and stabilizes HJs [37]. A RuvA-HJ complex is the first crucial step for RuvB loading and for the formation of an ATP-dependent RuvAB motor [44; 45]. RuvB interacts with RecU [36]. RecU specifically binds HJ DNA [46; 47].