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Updated: Aug 30, 2026
Separation and Fractionation of Culture Filtrate Proteins (CFPs) from Mycobacterium tuberculosis
Published on: July 11, 2025
Crystallization and preliminary X-ray diffraction data of Mycobacterium tuberculosis FbpC1 (Rv3803c)
Rosalind A Wilson1, Sonia Rai, Willian N Maughan
1School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, England.
Abstract:
The heterotrimeric antigen 85 complex (Ag85) is a major component of the cell wall of Mycobacterium tuberculosis and consists of three abundantly secreted proteins (FbpA, FbpB and FbpC2). These play key roles in the pathogenesis of tuberculosis and in maintaining cell-wall integrity. A homologue of the Ag85 subunits ( approximately 40% identity) was recently annotated in the M. tuberculosis genome as FbpC1. Unlike the Ag85-complex components, FbpC1 lacks mycolyltransferase activity and its function remains to be established. In order to aid functional characterization, FbpC1 has been crystallized. At room temperature, tetragonal crystals of FbpC1 were obtained belonging to space group P4(1)2(1)2 (unit-cell parameters a = b = 109.9, c = 61.8 A), yet when frozen the crystals underwent a phase transition to orthorhombic symmetry, space group P2(1)2(1)2(1) (a = 59.9, b = 108.9, c = 109.9 A). Diffraction data complete to 1.7 A resolution were recorded at 100 K at the synchrotron.
Insights
Researchers crystallized Mycobacterium tuberculosis FbpC1, a protein related to the antigen 85 complex. This structural study aims to uncover FbpC1
Area of Science:
- Structural Biology
- Mycobacterial Pathogenesis
Background:
- The antigen 85 complex (Ag85) is crucial for Mycobacterium tuberculosis cell wall integrity and pathogenesis.
- FbpC1 is a newly identified homologue of Ag85 subunits in M. tuberculosis, lacking mycolyltransferase activity.
- The precise function of FbpC1 remains undetermined.
Purpose of the Study:
- To facilitate the functional characterization of FbpC1 through structural analysis.
- To obtain high-resolution structural data of FbpC1.
Main Methods:
- Crystallization of FbpC1 protein.
- X-ray diffraction data collection at 1.7 Å resolution at 100 K using synchrotron radiation.
- Analysis of crystal symmetry and unit-cell parameters at different temperatures.
Main Results:
- Tetragonal crystals of FbpC1 (space group P4(1)2(1)2) were obtained at room temperature.
- A phase transition to orthorhombic symmetry (space group P2(1)2(1)2(1)) occurred upon freezing.
- High-resolution diffraction data were successfully collected.
Conclusions:
- The study presents the successful crystallization and initial diffraction data of FbpC1.
- These findings provide a foundation for future structural studies to elucidate FbpC1's function in M. tuberculosis.
