Characterization of an MPLP6, a gene coding for a yeast phase specific, antigenic mannoprotein in Penicillium marneffei.
A gene encoding an antigenic mannoprotein of Penicillium marneffei, MPLP6, was isolated by an antibody screening approach and characterized. The polypeptide chain containing deduced 220 amino acids has a predicted molecular mass of 24 kDa. It has high similarity to Mp1p, the first mannoprotein antigen isolated from P. marneffei. The polypeptide sequence presents the property of cell wall mannoproteins by containing a putative N-terminal signal peptide and potential O-linked glycosylation sites. However, absence of a GPI-anchored signal sequence suggested that this protein is secreted. The MPLP6 transcript was present specifically in the pathogenic yeast form. The transcript was completely absent in the mold phase and conidia. The fusion protein produced in E. coli was Western immunoblotted with P. marneffei-infected human sera and 95% of the patients' sera were positive in the assay. None of the sera obtained from patients with aspergillosis, tuberculosis, histoplasmosis or cryptococcosis tested positive. These results suggest that Mplp6 can be used as a marker in a serodiagnostic assay.
Pongpom
Monsicha
M
Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand. patthamapp@yahoo.com
Vanittanakom
Nongnuch
N
D000595:Amino Acid Sequence; D000908:Antibodies, Fungal / Q000097:blood; D000946:Antigens, Fungal / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D001483:Base Sequence; D015415:Biomarkers / Q000097:blood; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D006031:Glycosylation; D006801:Humans; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010407:Penicillium / Q000235:genetics* / Q000276:immunology*; D021382:Protein Sorting Signals / Q000235:genetics; D011993:Recombinant Fusion Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D015415:Biomarkers; D004271:DNA, Fungal; D008562:Membrane Glycoproteins; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; C025363:mannoproteins