Gannoun-Zaki, L. | bioRxiv Science

bioRxiv2022

The Secreted Tyrosine Phosphatase PtpA promotes Staphylococcus aureus Intramacrophagic Survival Through Decrease of the SUMOylation Host Response

S. aureus is a human pathogen that is extremely adaptable and is the cause of a variety of nosocomial and community-acquired infectious illnesses. During infection, S. aureus affect the host cell in many ways to enable its own multiplication, spread, and evasion of host immune defense. One of S. aureus mechanism to survive is to inhibit the SUMOylation of host proteins in order to increase its intracellular survival and persistence for longer period of time. Here, we show that the reduction in the levels of cellular SUMO-conjugated proteins is associated to the PtpA secreted virulence factor, which results in a reduction of Ubc9 protein level, the essential enzyme of the SUMOylation modification. In addition, we demonstrated that the critical residue D120A, essential for PtpA phosphatase activity, is required. This study shows for the first time that the secreted phosphatase PtpA impedes the host SUMOylation response, thus promoting S. aureus survival at long-term infection.

microbiology↗

bioRxiv2019

The Coxiella burnetii secreted protein kinase CstK influences vacuole development and interacts with the GTPase-activating protein TBC1D5

Coxiella burnetii is the etiological agent of the emerging zoonosis Q fever. Crucial to the pathogenesis of this intracellular pathogen is the secretion of bacterial effectors into host cells by a Type 4b Secretion System (T4SS), to subvert host cell membrane trafficking, leading to the biogenesis of a parasitophorous vacuole allowing intracellular replication. The characterization of prokaryotic Serine/Threonine Protein Kinases (STPKs) in bacterial pathogens is emerging as an important strategy to better understand host-pathogen interactions. In this study, we investigated CstK (for Coxiella Ser/Thr kinase), a bacterial protein kinase identified in C. burnetii by in silico analysis. Here, we demonstrated that this putative protein kinase undergoes autophosphorylation on Ser, Thr, and Tyr residues, and phosphorylates a classical eukaryotic protein kinase substrate in vitro. This dual Ser/Thr and Tyr kinase activity is similarly observed for eukaryotic dual specificity Tyr phosphorylation-regulated kinase class. CstK is translocated during infections and localizes at Coxiella-containing vacuoles (CCVs). Moreover, a C. burnetii mutant strain overexpressing CstK displays a severe CCVs development phenotype, suggesting a finely tuned regulation by the bacterial kinase during infection. Protein-protein interaction studies identified the Rab7-GTPase activating protein (GAP) TBC1D5 as a candidate CstK-specific host target, suggesting a role for this eukaryotic GAP in Coxiella infections. Indeed, CstK colocalizes with TBC1D5 in non-infected cells, and TBC1D5 is recruited at CCVs during infection. Accordingly, depletion of TBC1D5 from infected cells significantly affects CCVs development. Our results indicate that CstK has a critical role during infection as a bacterial effector protein that interacts with host proteins to facilitate vacuole biogenesis and intracellular replication.

microbiology↗