Intracellular mycobacterial proteome

Li, Qingbo

Abstract

Over the course of evolution, Mycobacterium tuberculosis has adapted a cognate interaction with host macrophages that allows it to become an extremely successful intracellular pathogen. The mechanism of latent tuberculosis in human remains unclear. It is a concern that tuberculosis pathology differs between murine and human at least at the primary infection stage. Difficulty in pathological study of tuberculosis in human subjects apparently is a major obstacle hindering further understanding of tuberculosis in man. Meanwhile, studying the intracellular mycobacterial proteome in human and murine macrophages may be a more accessible and worthwhile means to gain useful insight into the pathogenesis of M. tuberculosis and pathogen- host interaction, especially at a systems level. Our research interest vests in the intermediary metabolism pathway utilized by M. tuberculosis for intracellular growth and persistence. This project is to investigate the protein synthesis profile, the proteome, of M. tubeculosis H37Rv within human and murine macrophages using high resolution liquid-chromatography/linear ion trap-fourier transform mass spectrometry instrumentation and quantitative proteomics methods. We will compare the intracellular proteomes of M. tubeculosis H37Rv grown in the human acute monocytic leukemia cell line THP-1 versus in the C57BL/6-derived murine bone marrow macrophage cell line BMA3.1A7. Based on proteome profiles, we will identify the active intermediary metabolism pathway in intracellular M. tubeculosis H37Rv, particularly the half tricarboxylic acid (TCA) cycles split by the lack of ?-ketoglutarate dehydrogenase. The split reductive TCA half cycle along with the glyoxylate bypass come into prominence when mycobacteria strive for survival under oxygen and nutrient limitation. They may be important for understanding the physiology of intracellular persistence of mycobacteria within different macrophages.