Genus-Specific Interactions of Bacterial Chromosome Segregation Machinery Are Critical for Their Function

Abstract

Most bacteria use the ParABS system to segregate their newly replicated chromosomes. The two protein components of this system from various bacterial species share their biochemical properties: ParB is a CTPase that binds specific centromere-like parS sequences to assemble a nucleoprotein complex, while the ParA ATPase forms a dimer that binds DNA non-specifically and interacts with ParB complexes. The ParA-ParB interaction incites the movement of ParB complexes toward the opposite cell poles. However, apart from their function in chromosome segregation, both ParAB may engage in genus-specific interactions with other protein partners. One such example is the polar-growth controlling protein DivIVA in Actinomycetota, which binds ParA in Mycobacteria while interacts with ParB in Corynebacteria. Here, we used heterologous hosts to investigate whether the interactions between DivIVA and ParA or ParB are maintained across phylogenic classes. Specifically, we examined interactions of proteins from four bacterial species, two belonging to the Gram positive Actinomycetota phylum and two belonging to the Gram-negative Pseudomonadota. We show that while the interactions between ParA and ParB are preserved for closely related orthologs, the interactions with polarly localised protein partners are not conferred by orthologous ParABs. Moreover, we demonstrate that heterologous ParA cannot substitute for endogenous ParA, despite their high sequence similarity. Therefore, we conclude that ParA orthologs are fine-tuned to interact with their partners, especially their interactions with polarly localised proteins are adjusted to particular bacterial species demands.

The interplay between the polar growth determinant DivIVA, the segregation protein ParA and their novel interaction partner PapM controls theMycobacterium smegmatiscell cycle by modulation of DivIVA subcellular distribution

“…Next, based on the obtained BTH results, we set out to examine PapM interactions with ParA and DivIVA using protein colocalization assays in E. coli. Earlier, we have shown that EGFP-ParA colocalized at the poles of E. coli cells with mCherry-DivIVA when coproduced (Pióro et al 2018(Pióro et al , 2022.…”

“…Upon interaction with segrosomes, ParA dimers hydrolyse ATP and are released from the nucleoid, while the ParB complex moves toward a higher concentration of the nucleoid-bound ParA (Lim et al 2014;Surovtsev, Campos, and Jacobs-Wagner 2016). Surprisingly, the ParAB-mediated segregation shows some bacterial species-specific features (Kawalek et al 2020;Pióro et al 2022;Pióro and Jakimowicz 2020). These differences involve the interactions of the segregation proteins with other proteins or protein complexes, like the cell elongation complex which governs polar cell extension in Actinobacteria, such as Mycobacteria.…”

“…The unique features of mycobacterial chromosome segregation further include the interaction between ParA and DivIVA (Ginda et al 2013;Pióro et al 2018Pióro et al , 2022. Disruption of ParA-DivIVA binding results in modest segregation defects (Pióro et al 2018).…”

The interplay between the polar growth determinant DivIVA, the segregation protein ParA, and their novel interaction partner PapM controls the Mycobacterium smegmatis cell cycle by modulation of DivIVA subcellular distribution

“…Upon interaction with segrosomes, ParA dimers hydrolyze ATP and are released from the nucleoid, while the ParB complex moves toward a higher concentration of the nucleoid-bound ParA ( 7 , 8 ). Surprisingly, the ParAB-mediated segregation shows some bacterial species-specific features ( 4 , 9 , 10 ). These differences involve the interactions of the segregation proteins with other proteins or protein complexes, like the cell elongation complex which governs polar cell extension in Actinobacteria, such as mycobacteria.…”

“…The unique features of mycobacterial chromosome segregation further include the interaction between ParA and DivIVA ( 9 , 34 , 37 ). Disruption of ParA-DivIVA binding results in modest segregation defects ( 37 ).…”