Related Experiment Video

Updated: May 11, 2026

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
11:33

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking

Published on: December 17, 2013

Structure of the mycosin-1 protease from the mycobacterial ESX-1 protein type VII secretion system

Matthew Solomonson1, Pitter F Huesgen, Gregory A Wasney

  • 1Department of Biochemistry and Molecular Biology and Centre for Blood Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.

The Journal of Biological Chemistry
|April 27, 2013
PubMed

Insights

Researchers determined the structure of a key enzyme, mycosin protease 1 (MycP1), involved in Mycobacterium tuberculosis secretion. This structure reveals a unique regulatory mechanism essential for processing secreted proteins during infection.

Area of Science:

  • Structural Biology
  • Microbiology
  • Biochemistry

Background:

  • Mycobacteria utilize type VII (ESX) secretion systems for protein export across complex cell walls.
  • Mycobacterium tuberculosis possesses five ESX systems, with ESX-1 crucial for pathogenesis.
  • Mycosins (MycP) are extracellular proteases essential for ESX secretion and protein processing.

Purpose of the Study:

  • To elucidate the three-dimensional structure of mycosin protease 1 (MycP1).
  • To investigate the regulatory mechanism of MycP1 activity.
  • To determine MycP1's role in processing ESX-1 secreted proteins.

Main Methods:

  • X-ray crystallography was employed to determine the structure of MycP1(24-407) at 1.86 Å resolution.
  • Bioinformatic analysis was used to compare the N-terminal extension to known protease propeptides.
  • In vitro cleavage assays were performed using MycP1 and the ESX-1 secreted protein EspB.

Main Results:

  • The crystal structure revealed a subtilisin-like fold with a unique N-terminal extension.
  • This N-terminal extension does not resemble known propeptides but intimately interacts with the catalytic domain, stabilized by a disulfide bond.
  • MycP1 was shown to cleave the ESX-1 secreted protein EspB from both M. tuberculosis and Mycobacterium smegmatis at a conserved site.

Conclusions:

  • The unique structure of MycP1 suggests a novel mechanism for protease regulation.
  • MycP1 plays a direct role in processing ESX-1 secreted substrates like EspB.
  • Understanding MycP1's structure and function provides insights into ESX secretion and Mycobacterium pathogenesis.
Keywords:
ESXMicrobiologyMycobacteriaMycobacterium tuberculosisProteaseProtein SecretionSubtilisinType VII Secretion System

More Related Videos

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep105011:27

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

Published on: May 13, 2020

Combining X-Ray Crystallography with Small Angle X-Ray Scattering to Model Unstructured Regions of Nsa1 from S. Cerevisiae09:15

Combining X-Ray Crystallography with Small Angle X-Ray Scattering to Model Unstructured Regions of Nsa1 from S. Cerevisiae

Published on: January 10, 2018

Related Concept Videos

The Proteasome Structure01:17

The Proteasome Structure

The ubiquitin-proteasome pathway is a well-known mechanism utilized by eukaryotic cells to remove cytoplasmic proteins that are misfolded, damaged, or no longer needed. In this pathway, the protein that needs to be eliminated undergoes a process called ubiquitination, where a chain of ubiquitin molecules is attached to the 48th lysine residue of the target protein. This ubiquitin modification helps the proteasome distinguish between a target protein and a healthy protein.
The proteasome is an...
Overview of Myosin Structure and Function01:15

Overview of Myosin Structure and Function

Myosins are a family of molecular motor proteins, first identified in the skeletal muscles, where they are responsible for muscle contraction. Along with their role in muscle contraction, these proteins also play a role in the intracellular transport of molecules and vesicles. There are twenty-four classes of myosins based on their domain sequence and organization. Of the twenty-four, six classes (Myosin I, Myosin II, Myosin V, Myosin VI, Myosin VII, and Myosin X)  have been well characterized.
Caspases01:24

Caspases

Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
Insertion of Single-pass Transmembrane Proteins in the RER01:26

Insertion of Single-pass Transmembrane Proteins in the RER

Integral membrane proteins are proteins adhered to the lipid bilayer of a cell organelle or membrane. They can be of two types: transmembrane integral proteins that span the lipid bilayer and monotopic proteins that are attached to either side of the membrane but do not pass through it.
Integral transmembrane proteins possess transmembrane and extra membrane domains. The transmembrane domains are primarily made of 20-25 hydrophobic amino acids arranged in a helical secondary confirmation. These...
Gram-negative Bacterial Protein Secretion Systems01:17

Gram-negative Bacterial Protein Secretion Systems

Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...
Septins01:19

Septins

Septins are protein filaments forming the cytoskeleton along with the microtubules, microfilaments, intermediate filaments, and other accessory proteins. In 1971 while studying the cell division cycle in mutant Saccharomyces cerevisiae Harwell et al. first identified the septin-related genes playing a crucial role in yeast cytokinesis. Fluorescence microscopy revealed that these proteins localize at the budding neck as rings. These ring-like proteins were then named Septins by John Pringle, and...