Matrix metalloproteinase proteolysis of the mycobacterial HSP65 protein as a potential source of immunogenic peptides in human tuberculosis
Massachusetts Supranational Tuberculosis Reference Laboratory; Center for Health Policy and Research; Department of Medicine, Division of Infectious Diseases And Immunology
Adaptive Immunity; Amino Acid Sequence; Antigens, Bacterial; Bacterial Proteins; Catalytic Domain; Chaperonin 60; Epitopes; Humans; Hydrolysis; Immunomodulation; Isoenzymes; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Molecular Sequence Data; Mycobacterium tuberculosis; Peptide Fragments; Protease Inhibitors; Recombinant Proteins; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity; Tuberculosis
Bacterial Infections and Mycoses | Immunology and Infectious Disease
Mycobacterium tuberculosis is the causative agent of human tuberculosis (TB). Mycobacterial secretory protein ESAT-6 induces matrix metalloproteinase (MMP)-9 in epithelial cells neighboring infected macrophages. MMP-9 then enhances recruitment of uninfected macrophages, which contribute to nascent granuloma maturation and bacterial growth. Disruption of MMP-9 function attenuates granuloma formation and bacterial growth. The abundant mycobacterial 65 kDa heat shock protein (HSP65) chaperone is the major target for the immune response and a critical component in M. tuberculosis adhesion to macrophages. We hypothesized that HSP65 is susceptible to MMP-9 proteolysis and that the resulting HSP65 immunogenic peptides affect host adaptive immunity. To identify MMPs that cleave HSP65, we used MMP-2 and MMP-9 gelatinases, the simple hemopexin domain MMP-8, membrane-associated MMP-14, MMP-15, MMP-16 and MMP-24, and glycosylphosphatidylinositol-linked MMP-17 and MMP-25. We determined both the relative cleavage efficiency of MMPs against the HSP65 substrate and the peptide sequence of the cleavage sites. Cleavage of the unstructured PAGHG474L C-terminal region initiates the degradation of HSP65 by MMPs. This initial cleavage destroys the substrate-binding capacity of the HSP65 chaperone. Multiple additional cleavages of the unfolded HSP65 then follow. MMP-2, MMP-8, MMP-14, MMP-15 and MMP-16, in addition to MMP-9, generate the known highly immunogenic N-terminal peptide of HSP65. Based on our biochemical data, we now suspect that MMP proteolysis of HSP65 in vivo, including MMP-9 proteolysis, also results in the abundant generation of the N-terminal immunogenic peptide and that this peptide, in addition to intact HSP65, contributes to the complex immunomodulatory interplay in the course of TB infection.
DOI of Published Version
FEBS J. 2011 Sep;278(18):3277-86. doi: 10.1111/j.1742-4658.2011.08244.x. Link to article on publisher's site
The FEBS journal
Shiryaev, Sergey A.; Cieplak, Piotr; Aleshin, Alexander E.; Sun, Qing; Zhu, Wenhong; Motamedchaboki, Khatereh; Sloutsky, Alexander; and Strongin, Alex Y., "Matrix metalloproteinase proteolysis of the mycobacterial HSP65 protein as a potential source of immunogenic peptides in human tuberculosis" (2011). Center for Health Policy and Research (CHPR) Publications. 103.