Screening Mycobacterium tuberculosis secreted proteins identifies Mpt64 as eukaryotic membrane-binding virulence factor

Abstract

word count: 203 22 23 2 Text word count: 7,901 24 3 Abstract 25Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is one of the 26 most successful human pathogens. One reason for its success is that Mtb can reside 27 within host macrophages, a cell type that normally functions to phagocytose and destroy 28 infectious bacteria. However, Mtb is able to evade macrophage defenses in order to 29 survive for prolonged periods of time. Many intracellular pathogens secret virulence 30 factors targeting host membranes and organelles to remodel their intracellular 31 environmental niche. We hypothesized that Mtb exported proteins that target host 32 membranes are vital for Mtb to adapt to and manipulate the host environment for 33 survival. Thus, we characterized 200 exported proteins from Mtb for their ability to 34 associate with eukaryotic membranes using a unique temperature sensitive yeast 35 screen and to manipulate host trafficking pathways using a modified inducible secretion 36 screen. We identified five Mtb exported proteins that both associated with eukaryotic 37 membranes and altered the host secretory pathway. One of these secreted proteins, 38Mpt64, localized to the endoplasmic reticulum during Mtb infection of murine and human 39 macrophages and was necessary for Mtb survival in primary human macrophages. 40