Related Experiment Video
Updated: Jul 11, 2026
Separation and Fractionation of Culture Filtrate Proteins (CFPs) from Mycobacterium tuberculosis
Published on: July 11, 2025
Identification of novel bacterial plasminogen-binding proteins in the human pathogen Mycobacterium tuberculosis
Wendy Xolalpa1, Antonio J Vallecillo, Martha Lara
1Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México, D.F., México.
Abstract:
Binding and activation of human plasminogen (Plg) to generate the proteolytic enzyme plasmin (Plm) have been associated with the invasive potential of certain bacteria. In this work, proteomic analysis together with ligand blotting assays identified several major Plg-binding spots in Mycobacterium tuberculosis soluble extracts (SEs) and culture filtrate proteins. The identity of 15 different proteins was deduced by N-terminal and/or MS and corresponded to DnaK, GroES, GlnA1, Ag85 complex, Mpt51, Mpt64, PrcB, MetK, SahH, Lpd, Icl, Fba, and EF-Tu. Binding of Plg to recombinant M. tuberculosis DnaK, GlnA1, and Ag85B was further confirmed by ELISA and ligand blotting assays. The binding was inhibited by epsilon-aminocaproic acid, indicating that the interaction involved lysine residues. Plg bound to recombinant mycobacterial proteins was activated to Plm by tissue-type Plg activator. In contrast with recombinant proteins, M. tuberculosis SE enhanced several times the Plg activation mediated by the activator. Interestingly, GlnA1 was able to bind the extracellular matrix (ECM) protein fibronectin. Together these results show that M. tuberculosis posses several Plg receptors suggesting that bound Plg to bacteria surface, can be activated to Plm, endowing bacteria with the ability to break down ECM and basal membranes proteins contributing to tissue injury in tuberculosis.
Insights
Mycobacterium tuberculosis binds human plasminogen (Plg) using multiple bacterial proteins. This binding facilitates Plg activation to plasmin (Plm), aiding bacterial invasion and tissue damage in tuberculosis.
Area of Science:
- Microbiology
- Biochemistry
- Tuberculosis Research
Background:
- Bacterial invasion and virulence are often linked to plasminogen (Plg) binding and activation.
- Understanding the molecular mechanisms of bacterial interaction with host proteins is crucial for developing anti-virulence strategies.
Purpose of the Study:
- To identify and characterize plasminogen (Plg)-binding proteins from Mycobacterium tuberculosis.
- To investigate the role of these proteins in Plg activation and potential contribution to tuberculosis pathogenesis.
Main Methods:
- Proteomic analysis (ligand blotting, N-terminal sequencing, MS) to identify Plg-binding proteins.
- ELISA and ligand blotting to confirm binding of Plg to recombinant mycobacterial proteins.
- Assays to assess Plg activation to plasmin (Plm) by tissue-type Plg activator.
Main Results:
- Fifteen Mycobacterium tuberculosis proteins, including DnaK, GroES, GlnA1, and Ag85 complex, were identified as Plg binders.
- Binding of Plg to recombinant proteins (DnaK, GlnA1, Ag85B) was confirmed and shown to involve lysine residues.
- Bound Plg was activated to Plm by tissue-type Plg activator, with M. tuberculosis soluble extracts enhancing this activation.
- The protein GlnA1 demonstrated binding to extracellular matrix protein fibronectin.
Conclusions:
- Mycobacterium tuberculosis possesses multiple plasminogen receptors on its surface.
- Bacterial Plg binding and subsequent activation to Plm may facilitate bacterial dissemination and tissue degradation in tuberculosis.
- These findings highlight potential targets for novel anti-tuberculosis therapies aimed at inhibiting bacterial virulence.
