A DISORDERED REGION RETAINS THE FULL PRO- TEASE INHIBITOR ACTIVITY AND THE CAPACITY TO IN- DUCE CD8+ T CELLS IN VIVO OF THE ORAL VACCINE ADJUVANT U-OMP19

M. LAURA DARRIBA; CELESTE PUEBLAS CASTRO; LORENA M. CORIA; LAURA BRUNO; LUCIA B. CHEMES; RODOLFO M. RASIA; SEBASTIÁN KLINKE; JULIANA CASSATARO; KARINA A. PASQUEVICH

Congreso; LXX REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA (SAI); 2022

U-Omp19 is a bacterial protease inhibitor from Brucella abortus thatinhibits gastrointestinal and lysosomal proteases, enhancing thehalf-life and immunogenicity of co-delivered antigens. U-Omp19 isa novel adjuvant that is in preclinical development with various vac-cine candidates. However, the molecular mechanisms by which U-Omp19 exerts these functions and the structural elements responsi-ble for these activities remain unknown. To elucidate the molecularbasis of the U-Omp19 protease inhibitor and adjuvant activities weperformed a structural, biochemical, and functional characterizationof U-Omp19. Protein crystallography and NMR studies revealedthat the protein consists of a compact C-terminal beta-barrel do-main and a flexible N-terminal domain. To evaluate the contributionof each domain to U-Omp19´s activities several truncated proteinconstructs were designed and obtained. Our results demonstratethat the N-terminal domain behaves as an intrinsically disorderedprotein and that it retains the full protease inhibitor and adjuvantactivities of U-Omp19. Collectively, these results may contribute tofulfill the need for vaccine adjuvant development by offering insightsinto the U-Omp19 biological mechanisms of action and by enablingthe design of novel engineered structures that may have enhancedactivity, stability, or be conjugated with other bioactive molecules orvaccine antigens