Mycobacterium tuberculosis is protected from NADPH oxidase and LC3-associated phagocytosis by the LCP protein CpsA

Mycobacterium tuberculosis’success as a pathogen comes from itsability to evade degradation by macrophages. Normally macro-phages clear microorganisms that activate pathogen-recognitionreceptors (PRRs) through a lysosomal-trafficking pathway called“LC3-associated phagocytosis”(LAP). AlthoughM.tuberculosisac-tivates numerous PRRs, for reasons that are poorly understoodLAP does not substantially contribute toM.tuberculosiscontrol.LAP depends upon reactive oxygen species (ROS) generated byNADPH oxidase, butM.tuberculosisfails to generate a robustoxidative response. Here, we show that CpsA, a LytR-CpsA-Psr(LCP) domain-containing protein, is required forM.tuberculosisto evade killing by NADPH oxidase and LAP. Unlike phagosomescontaining wild-type bacilli, phagosomes containing theΔcpsAmutant recruited NADPH oxidase, produced ROS, associated withLC3, and matured into antibacterial lysosomes. Moreover, CpsAwas sufficient to impair NADPH oxidase recruitment to fungal par-ticles that are normally cleared by LAP. Intracellular survival of theΔcpsAmutant was largely restored in macrophages missing LAPcomponents (Nox2,Rubicon,Beclin,Atg5,Atg7,orAtg16L1) butnot in macrophages defective in a related, canonical autophagypathway (Atg14,Ulk1,orcGAS). TheΔcpsAmutant was highlyimpaired in vivo, and its growth was partially restored in micedeficient in NADPH oxidase,Atg5,orAtg7, demonstrating thatCpsA makes a significant contribution to the resistance ofM.tu-berculosisto NADPH oxidase and LC3 trafficking in vivo. Overall,our findings reveal an essential role of CpsA in innate immuneevasion and suggest that LCP proteins have functions beyond theirpreviously known role in cell-wall metabolism. BMDMs were seeded at 1.6E6 cells per well in a six-well plate 1 d before infection. Cells were uninfected or infected with H37Rv or ΔcpsA using a MOI of 4 in triplicate. At 4 hpi, RNA was prepared using the Direct-Zol RNA Mini-Prep Kit