Depolymerization of SUMO chains in T. brucei bloodstream parasites as a signal to control growth during infections

BERAZATEGUI, MARÍA AGUSTINA; CORIA, LORENA; ALVAREZ, VANINA EDER; SAURA, ANDREU; CASSATARO, JULIANA; IRIBARREN, PAULA ANA; DI MARZIO, LUCÍA AYELÉN; NAVARRO, MIGUEL

Mar del Plata

Congreso; XXXI Reunión Anual de la Sociedad argentina de Protozoología; 2019

SAP

SUMOylation is a reversible post-translational modification (PTM) that involves the attachment of one SUMO protein or SUMO chains to internal lysines in target proteins. This PTM enables rapid cellular responses, which are essential to pathogenic microorganisms that undergo complex life cycles involving several hosts, as is the case with trypanosomatids. Since we have previously shown that T. brucei is capable of forming SUMO polymeric chains in vitro, our next goals were to determine if this also occurs in vivo and to study their physiological relevance. To achieve this, we generated SUMO chain mutant parasites by replacing the endogenous SUMO alleles with a lysine deficient variant unable to polymerize. This transgenic cell line did not exhibit any evident phenotype and grew equivalent to WT parasites when culture in vitro. However, there were striking differences when using a mouse model of infection. While WT parasite grew uncontrollably killing the host 5-6 days after infection, SUMO mutant parasites limited their growth, generating oscillating parasitemia with prolonged host survival. Knowing that naturally occurring parasites achieve long-term infections inducing differentiation to a quiescent stage, we next examined differentiation kinetics of these parasites by an in vitro approach exposing them to cis-aconitate (CA) at low temperatures. Differentiation from BF to prociclic form (PF) was evaluated by immunofluorescence visualizing the switching from VSG to procyclin. SUMO mutant parasite showed an accelerated differentiation kinetics, suggesting that the absence of SUMO chains favors differentiation of the parasite and allows it to successfully establish and maintain an infection.