TY - JOUR
T1 - MAG2, a toxoplasma gondii bradyzoite stage-specific cyst matrix protein
AU - Tu, Vincent
AU - Mayoral, Joshua
AU - Yakubu, Rama R.
AU - Tomita, Tadakimi
AU - Sugi, Tatsuki
AU - Han, Bing
AU - Williams, Tere
AU - Ma, Yanfen
AU - Weiss, Louis M.
N1 - Publisher Copyright:
© 2020 Tu et al.
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Toxoplasma gondii causes a chronic infection that affects a significant portion of the world's population, and this latent infection is the source of reactivation of toxoplasmosis. An attribute of the slowly growing bradyzoite stage of the parasite is the formation of a cyst within infected cells, allowing the parasite to escape the host's immune response. In this study, a new bradyzoite cyst matrix antigen (MAG) was identified through a hybridoma library screen. This cyst matrix antigen, matrix antigen 2 (MAG2), contains 14 tandem repeats consisting of acidic, basic, and proline residues. Immunoblotting revealed that MAG2 migrates at a level higher than its predicted molecular weight, and computational analysis showed that the structure of MAG2 is highly disordered. Cell fractionation studies indicated that MAG2 was associated with both insoluble and soluble cyst matrix material, suggesting that it interacts with the intracyst network (ICN). Examination of the kinetics of MAG2 within the cyst matrix using fluorescence recovery after photobleaching (FRAP) demonstrated that MAG2 does not readily diffuse within the cyst matrix. Kinetic studies of MAG1 demonstrated that this protein has different diffusion kinetics in tachyzoite and bradyzoite vacuoles and that its mobility is not altered in the absence of MAG2. In addition, deletion of MAG2 does not influence growth, cystogenesis, or cyst morphology. IMPORTANCE This report expands on the list of characterized Toxoplasma gondii cyst matrix proteins. Using fluorescence recovery after photobleaching (FRAP), we have shown that matrix proteins within the cyst matrix are not mainly in a mobile state, providing further evidence of how proteins behave within the cyst matrix. Understanding the proteins expressed during the bradyzoite stage of the parasite reveals how the parasite functions during chronic infection.
AB - Toxoplasma gondii causes a chronic infection that affects a significant portion of the world's population, and this latent infection is the source of reactivation of toxoplasmosis. An attribute of the slowly growing bradyzoite stage of the parasite is the formation of a cyst within infected cells, allowing the parasite to escape the host's immune response. In this study, a new bradyzoite cyst matrix antigen (MAG) was identified through a hybridoma library screen. This cyst matrix antigen, matrix antigen 2 (MAG2), contains 14 tandem repeats consisting of acidic, basic, and proline residues. Immunoblotting revealed that MAG2 migrates at a level higher than its predicted molecular weight, and computational analysis showed that the structure of MAG2 is highly disordered. Cell fractionation studies indicated that MAG2 was associated with both insoluble and soluble cyst matrix material, suggesting that it interacts with the intracyst network (ICN). Examination of the kinetics of MAG2 within the cyst matrix using fluorescence recovery after photobleaching (FRAP) demonstrated that MAG2 does not readily diffuse within the cyst matrix. Kinetic studies of MAG1 demonstrated that this protein has different diffusion kinetics in tachyzoite and bradyzoite vacuoles and that its mobility is not altered in the absence of MAG2. In addition, deletion of MAG2 does not influence growth, cystogenesis, or cyst morphology. IMPORTANCE This report expands on the list of characterized Toxoplasma gondii cyst matrix proteins. Using fluorescence recovery after photobleaching (FRAP), we have shown that matrix proteins within the cyst matrix are not mainly in a mobile state, providing further evidence of how proteins behave within the cyst matrix. Understanding the proteins expressed during the bradyzoite stage of the parasite reveals how the parasite functions during chronic infection.
KW - Bradyzoite
KW - Cyst matrix
KW - Fluorescence recovery after photobleaching (FRAP)
KW - Intravacuolar network
KW - Latency
KW - MAG1
KW - MAG2
KW - Monoclonal antibody screen
KW - Toxoplasma gondii
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U2 - 10.1128/MSPHERE.00100-20
DO - 10.1128/MSPHERE.00100-20
M3 - Article
C2 - 32075884
AN - SCOPUS:85079755879
SN - 2379-5042
VL - 5
JO - mSphere
JF - mSphere
IS - 1
M1 - e00100-20
ER -