Anales RANF

P.19 EXTRACELLULAR NUCLEOTIDE METABOLISM IN THE CONTEXT OF YEAST-HOST INTERACTION L. Rodrigues 1,2 , A.R.Mestre 3 , G.Silva 3 , T.Russo-Abrahão 4 , R.A. Cunha 1,2 , J.R.Meyer- Fernandes 4 , T. Gonçalves 1,2 1 CNC-Center for Neurosciences and Cell Biology, Coimbra, Portugal; 2 Faculty of Medicine-University of Coimbra, Coimbra, Portugal; 3 Faculty of Science and Technology-University of Coimbra, Coimbra, Portugal; 4 Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. Ectophosphatase and ectonucleotidase activities are recognized to influence the infectious potential of several microbes, including Candida albicans and other non- albicans Candida species, which are important human agents of infection. 1 Several studies have revealed that the conversion of extracellular ATP into adenosine determines the efficiency of microorganisms infection. 2,3 In fact, in recent years and due to its anti-inflammatory and immunosuppressive effects, adenosine and its sensing devices, namely adenosine A 2A receptors, have emerged as important targets in the context of infection. The present work aims to characterize the ectonucleotidase activities in Candida spp. and to explore its relevance in the evasion of the immune system by yeasts. We found that C. albicans does not have a classical ecto-5’-nucleotidase enzyme 5 since, together with C. glabrata and Saccharomyces cerevisiae , it can also use 3’AMP as a substrate, under acidic pH conditions. In resemblance with other previously described mechanisms 4 , this 3’-nucleotidase/nuclease activity seems to be important for yeasts to escape Neutrophils Extracellular Traps. In conclusion, although the exact nature and specificity of yeasts ectonucleotidases are not completely established, we highlighted the importance of those enzymes in the context of infection, helping yeasts to overcome host defenses, through its involvement in yeast-to-hypha transition, survival and persistence either in the epithelial surfaces and/or once internalized by phagocytic cells. 1) Mayer et al. Virulence . 2013;4:119–128. 2) Németh et al. J Immunol.2006;176:5616-5626. 3) Thammavongsa et al. J Exp Med.2009;206:2417-2427. 4) Guimarães-Costa et al. Infect Immun . 2014;82:1732-40. 5) Rodrigues et al. FEMS Microbiol Lett.2016;363(1):fnv212.