title: Expression, secretion, and glycosylation of the 45- and 47-kDa glycoprotein of Mycobacterium tuberculosis in Streptomyces lividans.
abstract: The gene encoding the 45/47 kDa glycoprotein (Rv1860) of Mycobacterium tuberculosis was expressed in Streptomyces lividans under its own promoter and under the thiostrepton-inducible Streptomyces promoter PtipA. The recombinant protein was released into the culture medium and, like the native protein, migrated as a double band at 45 and 47 kDa in sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) gels. However, in contrast to the native protein, only the 47-kDa recombinant protein could be labeled with concanavalin A (ConA). Carbohydrate digestion with jack bean alpha-D-mannosidase resulted in a reduction in the molecular mass of the recombinant protein upper band and completely eliminated ConA binding. Two-dimensional gel electrophoresis revealed only one isoelectric point for the recombinant protein. Comparative fingerprinting analysis of the individually purified upper and lower recombinant protein bands, treated under the same conditions with specific proteases, resulted in similar peptide patterns, and the peptides had the same N-terminal sequence, suggesting that migration of the recombinant protein as two bands in SDS-PAGE gels could be due to differences in glycosylation. Mass spectrometry analysis of the recombinant protein indicated that as in native protein, both the N-terminal and C-terminal domains of the recombinant protein are glycosylated. Furthermore, it was determined that antibodies of human tuberculosis patients reacted mainly against the carbohydrate residues of the glycoprotein. Altogether, these observations show that expression of genes for mycobacterial antigens in S. lividans is very useful for elucidation of the functional role and molecular mechanisms of glycosylation in bacteria.
authors.affiliation: Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F., México.
authors.forename: Martha
authors.initials: M
authors.lastname: Lara
authors.forename: Luis
authors.initials: L
authors.lastname: Servín-González
authors.forename: Mahavir
authors.initials: M
authors.lastname: Singh
authors.forename: Carlos
authors.initials: C
authors.lastname: Moreno
authors.forename: Ingrid
authors.initials: I
authors.lastname: Cohen
authors.forename: Manfred
authors.initials: M
authors.lastname: Nimtz
authors.forename: Clara
authors.initials: C
authors.lastname: Espitia
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*; D014397:Tuberculosis, Pulmonary / Q000276:immunology
chemical_list: C095715:45-47 kDa antigen complex, Mycobacterium; D001426:Bacterial Proteins; D006023:Glycoproteins; D007106:Immune Sera; D011994:Recombinant Proteins