Mehner-Breitfeld, D. | bioRxiv Science

bioRxiv2025

The ParA-like ATPase PldP influences the TatA dynamics in Corynebacterium glutamicum

In bacterial cells, precise localization of protein complexes is achieved by unique positioning systems. One of the examples of such positioning systems is the ParAB-parS which is responsible for plasmid and chromosome segregation. In Corynebacterium glutamicum, a parAB deletion results in cell division and growth defects, while deletion of an orphan ParA-like protein pldP results only in a moderate cell division phenotype. Having confirmed a basal ATPase activity of PldP, we aimed to explore if the {Delta}pldP-related phenotype could be a consequence of the mislocalized secreted proteins, as the loss of extracellular proteins involved in cell wall metabolism results in a similar phenotype characterized by disrupted separation of daughter cells. Putative peptidoglycan hydrolase Rv2525c from Mycobacterium tuberculosis and Rv2525c-like glycoside hydrolase-like domain-containing protein Cg0955 from C. glutamicum were previously shown to be transported outside of the cell by twin-arginine protein translocation machinery (Tat). Here, we found that although the deletion of pldP did not lead to the altered secretion of the putative hydrolase Cg0955 by the Tat system, it resulted in the reduction of the Tat dynamics. Our findings highlight the interplay between the ParA-like ATPase PldP and the Tat translocon and contribute to the studies of ParA-like proteins being essential in positioning various cargos in the bacterial cells. ImportancePrecise spatio-temporal localization of protein complexes within a bacterial cell is essential for the survival and proliferation of bacteria. ParA-like ATPases play a crucial role in protein positioning, as well as chromosome and plasmid segregation. Here, we characterize a novel ParA-like ATPase PldP in Corynebacterium glutamicum, a model organism for the cell biology of Mycobacteriales and a biotechnological workhorse. Deletion of pldP results in the cell division phenotypes and impacts the intracellular dynamics of TatA, a component of the twin-arginine protein transport. We suggest that the mislocalization of the Tat-secreted putative peptidoglycan hydrolase caused by the indirect influence of pldP deletion might account for the observed cell separation defect.

microbiology↗

bioRxiv2021

TatA and TatB generate a hydrophobic mismatch that is important for function and assembly of the Tat translocon in Escherichia coli

The Tat system has the unique purpose to translocate folded proteins across energy-transducing membranes. It occurs in bacteria and archaea, as well as in eukaryotic organelles of bacterial origin. In the bacterial model system Escherichia coli, the three components TatA, TatB, and TatC assemble to functional translocons. TatA and TatB both possess an N-terminal transmembrane helix (TMH) that is followed by an amphipathic helix (APH). The TMHs of TatA and TatB generate a hydrophobic mismatch with only 12 consecutive hydrophobic residues that span the membrane. We shortened or extended this stretch of hydrophobic residues in either TatA, TatB, or both, and analyzed effects on transport functionality and translocon assembly. The wild type length functioned best but was not an absolute requirement, as some variation was clearly tolerated. Defects of shortenings or extensions were enhanced by simultaneous mutations in TatA and TatB, indicating partial compensations of mutations in TatA by wild type TatB or vice versa. Length variation in TatB destabilized TatBC-containing complexes, revealing that the 12-residues-length is important for Tat component interactions and translocon assembly. To also address potential effects on TatA associations, we characterized these by metal tagging transmission electron microscopy and carried out molecular dynamics simulations. In these simulations, interacting short TMHs of larger TatA assemblies were thinning the membrane together with laterally aligned tilted APHs that generated a deep V-shaped groove. The conserved length of 12 hydrophobic residues may thus not only be important for translocon interactions, but also for a membrane destabilization during Tat transport. If this is the case, the specific short length could be a compromise between functionality and proton leakage minimization.

biochemistry↗