Heterogeneity of S-layer proteins from aggregating and non-aggregating Lactobacillus kefir strains

PABLO MOBILI; MARÍA DE LOS ANGELES SERRADELL; SEBASTIÁN TREJO; FRANCESC X. AVILÉS PUIGVERT; ANALÍA G. ABRAHAM; GRACIELA L. DE ANTONI

ANTON LEEUW INT. J. G.

Springer Netherlands

Año: 2009 vol. 95 p. 363 - 372

0003-6072

Since the presence of S-layer proteinconditioned the autoaggregation capacity of somestrains of Lactobacillus kefir, S-layer proteins fromaggregating and non-aggregating L. kefir strains werecharacterized by immunochemical reactivity,MALDI-TOF spectrometry and glycosylation analysis.Two anti-S-layer monoclonal antibodies (Mab5F8and Mab1F8) were produced; in an indirect enzymelinkedimmunosorbent assay Mab1F8 recognizedS-layer proteins from all L. kefir tested while Mab5F8recognized only S-layer proteins from aggregatingstrains. Periodic Acid-Schiff staining of proteins afterpolyacrylamide gel electrophoresis under denaturingconditions revealed that all L. kefir S-layer proteinstested were glycosylated. Growth of bacteria in thepresence of the N-glycosylation inhibitor tunicamycinsuggested the presence of glycosydic chains O-linkedto the protein backbone. MALDI-TOF peptide mapfingerprint for S-layer proteins from 12 L. kefir strainsshowed very similar patterns for the aggregatingstrains, different from those for the non-aggregatingones. No positive match with other protein spectra inMSDB Database was found. Our results revealed ahigh heterogeneity among S-layer proteins fromdifferent L. kefir strains but also suggested a correlationbetween the structure of these S-layer glycoproteinsand the aggregation properties of whole bacterial cells.