Study of structural features and aggregation of S-layer proteins from lactobacilli

CASELLA, M.; BOLLA, P.A.; SERRADELL, M. DE LOS A.; PERUZZO, P.J.

Campinas

Congreso; 26 RAU - Reunión Anual de Usuarios; 2016

LNLS/CNPEM

Crystalline S-layers arethe outermost cell envelope components of many bacteria and archaea. S-layersare monomolecular arrays composed of identical protein or glycoprotein subunitswith molecular weights ranging from 40 to 200 kDa. Isolated S-layer proteins (SLP)show an intrinsic tendency to reassemble into regular arrays after removal ofthe disrupting agent used in the extraction procedure. The self-assemblyproducts generated in suspension may have the form of flatsheets, open-endedcylinders or closed vesicles [1]. In this work, SAXS measurements on SLPisolated from three different strains of Lactobaciluskefiri were performed using the SAXS1 beamline at the LNLS (Campinas,Brazil) wavelength 1.55°A; exposure time of 200 sec.; sample detector distanceof 1 m). In the first step the SLP in PBS was studied. In a second step the dynamicof protein aggregation in presence of Ca+2 was performed. Thescattering patterns of SLP were significantly different in absence or presenceof Ca+2. Moreover, the pair distribution function P(R) of SLP SAXSdata showed substantial variations as analyzed using the program GNOM, such as changesin Dmax of SLP upon addition of Ca+2. Particularly, Dmax of SLP fromLb. kefiri 8348 increased (from 20,35nmto 42,27nm) and Dmax of SLP from Lb.kefiri 5818 decreased (from 36,45nm to 15,07nm), meanwhile the SLP from Lb. kefiri83111 did not show significant changes.