Genetic Dissection of DivIVA Functions in Listeria monocytogenes

Abstract

DivIVA is a membrane binding protein that clusters at curved membrane regions, such as the cell poles and the membrane invaginations occurring during cell division. DivIVA proteins recruit many other proteins to these subcellular sites through direct protein-protein interactions. DivIVA-dependent functions are typically associated with cell growth and division, even though species-specific differences in the spectrum of DivIVA functions and their causative interaction partners exist. DivIVA from the Gram-positive human pathogen Listeria monocytogenes has at least three different functions. In this bacterium, DivIVA is required for precise positioning of the septum at midcell, it contributes to the secretion of autolysins required for the breakdown of peptidoglycan at the septum after the completion of cell division, and it is essential for flagellar motility. While the DivIVA interaction partners for control of division site selection are well established, the proteins connecting DivIVA with autolysin secretion or swarming motility are completely unknown. We set out to identify divIVA alleles in which these three DivIVA functions could be separated, since the question of the degree to which the three functions of L. monocytogenes DivIVA are interlinked could not be answered before. Here, we identify such alleles, and our results show that division site selection, autolysin secretion, and swarming represent three discrete pathways that are independently influenced by DivIVA. These findings provide the required basis for the identification of DivIVA interaction partners controlling autolysin secretion and swarming in the future.IMPORTANCE DivIVA of the pathogenic bacterium Listeria monocytogenes is a central scaffold protein that influences at least three different cellular processes, namely, cell division, protein secretion, and bacterial motility. How DivIVA coordinates these rather unrelated processes is not known. We here identify variants of L. monocytogenes DivIVA, in which these functions are separated from each other. These results have important implications for the models explaining how DivIVA interacts with other proteins.

Characterization of Conserved and Novel Septal Factors in Mycobacterium smegmatis

“…The presence of SepIVA at both the septum and IMD implies that these functional zones may have coordinated functions. Alternatively, the IMD could serve as reservoir to store SepIVA until it is needed in division, or SepIVA may have multiple independent functions, as has been seen in the DivIVA homolog from Listeria monocytogenes (65).…”

“…In S. pneumoniae, GpsB and DivIVA coordinate peptidoglycan synthesis between the septum and periphery, partly by interactions with the septal factor EzrA (68). DivIVA homologs in general seem to be involved in recruiting other proteins to their sites of activity and regulating them (25,65,69). Thus, we surmise that SepIVA may recruit and activate cell wall precursor enzymes or transmembrane cell wall enzymes that are required for the construction of the septal cross-wall, similarly to how Wag31 apparently regulates such enzymes during elongation (23,26,66).…”

Structural basis for interaction of DivIVA/GpsB proteins with their ligands

“…In L. monocytogenes , a close but pathogenic relative of B. subtilis , DivIVA is required for SecA2‐dependent secretion of autolysins, cell division (via MinCDJ) and flagellar motility (Halbedel et al , ; Kaval et al , ). These three functions can also be separated from each other by domain‐specific divIVA mutations (Kaval et al , ). It is not known which proteins link Lm DivIVA to autolysin secretion and flagellar motility, but as the LBD is essential for these phenomena it is likely that transmembrane proteins are involved (Kaval et al , ).…”

“…These three functions can also be separated from each other by domain‐specific divIVA mutations (Kaval et al , ). It is not known which proteins link Lm DivIVA to autolysin secretion and flagellar motility, but as the LBD is essential for these phenomena it is likely that transmembrane proteins are involved (Kaval et al , ). DivIVA proteins interact with an even greater variety of proteins in other species (Kaval & Halbedel, ) where the interaction of DivIVA with ParB/Spo0J homologs is commonly observed.…”

Higher order assembling of the mycobacterial essential polar growth factor DivIVA/Wag31

“…During sporulation in B. subtilis, bsDivIVA participates in polar anchoring of the chromosome origin, which is mediated by a DNA binding protein RacA (6,21). In Listeria monocytogenes, DivIVA play multiple roles in secretion of autolysins, division septum positioning and swarming motility (22)(23). In actinobacteria, DivIVA reportedly participates in cell-shape maintenance, origin tethering, protection against oxidative stress and directing the cell-wall biosynthetic proteins at the pole (15,(24)(25)(26)(27).…”