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

BOLLA PA; PERUZZO PJ; CASELLA M; SERRADELL MA

Campinas, Sao Paulo

Congreso; 26th Annual Users Meeting (RAU) LNLS/CNPEM; 2016

Brazilian Synchrotron Light Laboratory (LNLS/CNPEM)

Crystalline S-layers are the outermost cell envelope components of many bacteria and archaea. S-layers are monomolecular arrays composed of identical protein or glycoprotein subunits with molecular weights ranging from 40 to 200kDa. Isolated S-layer proteins (SLP) show an intrinsic tendency to reassemble into regular arrays after removal of the disrupting agent used in the extraction procedure. The self-assembly products generated in suspension may have the form of flatsheets, open-ended cylinders or closed vesicles. SAXS measurements are necessary to determinate the morphological parameters of SLP and complete the structural characterization. In this work, SAXS measurements on SLP isolated from different strains of Lactobacilus kefiri was performed at the SAXS1 beamline at the LNLS (Campinas, Brazil) using a monochromatic beam of wavelength 1.55°A and exposure time of 200 sec. The sample detector distance was fit on 1 m. In the first step the SLP in PBS was studied. In a second step the dynamic of aggregation of proteins in presence of Ca+2 was performed. The scattering patterns of SLP are significantly different in absence or presence of Ca+2. The pair distribution function P(R) of SLP SAXS data shows substantial variations as analyzed using the program GNOM. Upon addition of Ca+2 changes were detected on Dmax for each strain, Dmax of SLP from Lb. kefiri CIDCA 8348 increased (from 20,35 to 42,27), meanwhile the SLP from Lb. kefiri CIDCA 5818 decreased (from 36,45 to 15,07). On the other hand, the SLP from Lb. kefiri CIDCA 83111 did not showed significant changes.