Aminoacid sequencing and sugar composition of S-layer proteins from Lactobacillus kefiri strains

MALAMUD M; CAVALLERO G.; CARASI P; CASABUONO A; COUTO A; SERRADELL M

Mar del Plata

Congreso; LI Reunión anual de la SAIB; 2015

SAIB

Surface layers are (glyco)-proteinaceous cell envelopes ubiquitously found in different bacterial species, including L. kefiri, a potentially probiotic microorganism. Previous mass spectrometry analysis showed a great structural heterogeneity among glycosylated S-layer proteins (SLP) from different L. kefiri strains, some of them share several fragments with the SLP from phylogenetically related lactobacilli. Based on this information, specific primers were designed in order to amplify SLP gene?s fragments by PCR. A fragment of 340 bp length was amplified from DNA of 22 strains of L. kefiri. Multiple alignments of the deduced amino acid sequences demonstrated a strong sequence conservation of this fragment in all SLP studied, however it was possible to group strains in five different sets. The glycosylation signature motif SSASSASSA, recently described in L. buchneri CD34, was also found in all the strains. Glyco-SLP from four strains were selected and glycans obtained by β-elimination were further hydrolyzed and analyzed by HPAEC-PAD. All of them presented glucose as main component, although differences in minor components were detected. This is the first approach on characterization of primary structure of glycosylated SLP from L. kefiri strains. The results obtained are essential to understand the functional properties of these proteins as surface components of bacterial cells.