Group A Streptococcus modulates RAB1- and PIK3C3 complex-dependent autophagy.

ABSTRACT

Autophagy selectively targets invading bacteria to defend cells, whereas bacterial pathogens counteract autophagy to survive in cells. The initiation of canonical autophagy involves the PIK3C3 complex, but autophagy targeting Group A Streptococcus (GAS) is PIK3C3-independent. We report that GAS infection elicits both PIK3C3-dependent and -independent autophagy, and that the GAS effector NAD-glycohydrolase (Nga) selectively modulates PIK3C3-dependent autophagy. GAS regulates starvation-induced (canonical) PIK3C3-dependent autophagy by secreting streptolysin O and Nga, and Nga also suppresses PIK3C3-dependent GAS-targeting-autophagosome formation during early infection and facilitates intracellular proliferation. This Nga-sensitive autophagosome formation involves the ATG14-containing PIK3C3 complex and RAB1 GTPase, which are both dispensable for Nga-insensitive RAB9A/RAB17-positive autophagosome formation. Furthermore, although MTOR inhibition and subsequent activation of ULK1, BECN1, and ATG14 occur during GAS infection, ATG14 recruitment to GAS is impaired, suggesting that Nga inhibits the recruitment of ATG14-containing PIK3C3 complexes to autophagosome-formation sites. Our findings reveal not only a previously unrecognized GAS-host interaction that modulates canonical autophagy, but also the existence of multiple autophagy pathways, using distinct regulators, targeting bacterial infection.Abbreviations ATG5 autophagy related 5; ATG14 autophagy related 14; ATG16L1 autophagy related 16 like 1; BECN1 beclin 1; CALCOCO2 calcium binding and coiled-coil domain 2; GAS group A streptococcus; GcAV GAS-containing autophagosome-like vacuole; LAMP1 lysosomal associated membrane protein 1; MAP1LC3/LC3 microtubule associated protein 1 light chain 3; MTORC1 mechanistic target of rapamycin kinase complex 1; Nga NAD-glycohydrolase; PIK3C3 phosphatidylinositol 3-kinase catalytic subunit type 3; PtdIns3P phosphatidylinositol-3-phosphate; PtdIns4P phosphatidylinositol-4-phosphate; RAB RAB, member RAS oncogene GTPases; RAB1A RAB1A, member RAS oncogene family; RAB11A RAB11A, member RAS oncogene family; RAB17 RAB17, member RAS oncogene family; RAB24 RAB24, member RAS oncogene family; RPS6KB1 ribosomal protein S6 kinase B1; SLO streptolysin O; SQSTM1 sequestosome 1; ULK1 unc-51 like autophagy activating kinase 1; WIPI2 WD repeat domain, phosphoinositide interacting 2.