title: Heterogeneity of S-layer proteins from aggregating and non-aggregating Lactobacillus kefir strains.
abstract: Since the presence of S-layer protein conditioned the autoaggregation capacity of some strains of Lactobacillus kefir, S-layer proteins from aggregating and non-aggregating L. kefir strains were characterized by immunochemical reactivity, MALDI-TOF spectrometry and glycosylation analysis. Two anti-S-layer monoclonal antibodies (Mab5F8 and Mab1F8) were produced; in an indirect enzyme-linked immunosorbent assay Mab1F8 recognized S-layer proteins from all L. kefir tested while Mab5F8 recognized only S-layer proteins from aggregating strains. Periodic Acid-Schiff staining of proteins after polyacrylamide gel electrophoresis under denaturing conditions revealed that all L. kefir S-layer proteins tested were glycosylated. Growth of bacteria in the presence of the N-glycosylation inhibitor tunicamycin suggested the presence of glycosydic chains O-linked to the protein backbone. MALDI-TOF peptide map fingerprint for S-layer proteins from 12 L. kefir strains showed very similar patterns for the aggregating strains, different from those for the non-aggregating ones. No positive match with other protein spectra in MSDB Database was found. Our results revealed a high heterogeneity among S-layer proteins from different L. kefir strains but also suggested a correlation between the structure of these S-layer glycoproteins and the aggregation properties of whole bacterial cells.
authors.affiliation: Centro de Investigación y Desarrollo en Criotecnología de Alimentos, CCT La Plata, CONICET, 47 y 116 (s/n), La Plata, Argentina.
authors.forename: Pablo
authors.initials: P
authors.lastname: Mobili
authors.forename: María de Los Angeles
authors.initials: Mde L
authors.lastname: Serradell
authors.forename: Sebastián A
authors.initials: SA
authors.lastname: Trejo
authors.forename: Francesc X
authors.initials: FX
authors.lastname: Avilés Puigvert
authors.forename: Analía G
authors.initials: AG
authors.lastname: Abraham
authors.forename: Graciela L
authors.initials: GL
authors.lastname: De Antoni
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D043302:Cultured Milk Products / Q000382:microbiology*; D004797:Enzyme-Linked Immunosorbent Assay; D006031:Glycosylation; D007778:Lactobacillus / Q000737:chemistry* / Q000254:growth & development; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D008562:Membrane Glycoproteins; C055764:S-layer proteins