GENE SEQUENCING OF SIX NEW S-LAYER PROTEINS FROM PROBIOTIC LACTOBACILLUS KEFIRI STRAINS

ASSANDRI MH; MALAMUD M; SERRADELL MA

Paraná

Congreso; LIV Reunión Anual de SAIB; 2018

Surface layers are (glyco)-proteinaceous auto-assembled cell envelopes ubiquitously found in Bacteria and Archaea. Lactobacillus kefiri is a probiotic microorganism carrying a glycosylated S-layer which showed to have interesting functional properties. Recently, we obtained the amino acid sequences of ten S-layer proteins (SLP) from different strains of L. kefiri. Regarding several structural differences, different groups of strains were distinguished. In this work, we show the most recent results obtained for the SLP from two aggregative and four non-aggregative new L. kefiri strains belonging to our collection. Primers located outsides and inside the SLP genes were used to amplify genomic DNA. The amino acid sequences were deduced using ExPASy Translate Tool, and the theoretical properties were predicted using ProtParam software. The mature proteins contain between 541 and 568 amino acids, the percentage of hydrophobic amino acids varies from 34.9 to 38.6%, and the calculated pI ranges between 9.49 and 9.67. All the SLP present the O-glycosylation site SASSAS. The major differences among strains are found in the C-terminal region, while the N-terminal region is relatively conserved, which leads to cross-reactivity using a specific polyclonal mouse antiserum raised against one of the proteins (SLP8348). Each new sequenced SLP belongs to one of the groups previously defined, suggesting that this classification could be representative of the L. kefiri SLP family. Our results contribute to understanding the functional properties of the SLPs not only as surface bacterial components but also as unique macromolecules with high potential in nanobiotechnology.