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Rho GTPases are members of the Ras superfamily and are involved in signal transduction pathways, including maintenance of cell morphology and motility, cell cycle progression, and transcription activation. We report the molecular identification in trypanosomatids (Trypanosoma cruzi) of the first member of the Rho family. The cloned Rho protein, TcRho1, shares ϳ40% homology with other members of the Rho family. Southern blot analysis revealed that TcRHO1 is a single copy gene per haploid genome, and Northern blot assays showed a transcript of 1200 nucleotides in length. Mapping the 5-untranslated region of TcRHO1 transcripts revealed at least five different transcripts derived from differential trans-splicing. Three of the five transcripts contain the trans-splicing site within the coding region of the TcRHO1 gene. TcRho1 also contains the C-terminal sequence CQLF (CAAX motif), which is predicted to direct post-translation prenylation of the cysteine residue. A synthetic peptide containing this C-terminal motif, when tested against Q-Sepharose chromatography fractions from T. cruzi cytosol, was shown to be efficiently farnesylated, but not geranylgeranylated, despite the fact that the CAAX motif with X ‫؍‬ Phe specifies geranylgeranylation by mammalian protein geranylgeranyltransferase I. Furthermore, immunoblot analyses of epimastigote protein with anti-S-farnesylcysteine methyl ester and anti-TcRho1 antisera strongly suggested that TcRho1 is farnesylated in vivo. The farnesylation of proteins such as Rho GTPases could be the basis for the selective cytotoxic action of protein farnesyltransferase inhibitors on trypanosomatids versus mammalian cells.

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The protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas Disease, undergoes through a complex life cycle where rounds of cell division and differentiation occur initially in the gut of triatominae vectors and, after transmission, inside of infected cells in vertebrate hosts. Members of the Ras superfamily of GTPases are molecular switches which play pivotal regulatory functions in cell growth and differentiation. We have previously described a novel GTPase in T. cruzi, TcRjl, which belongs to the RJL family of Ras-related GTP binding proteins. Here we show that most of TcRjl protein is found bound to GTP nucleotides and may be locked in this stage. In addition, we show that TcRjl is located close to the kinetoplast, in a region corresponding possibly to flagellar pocket of the parasite and the expression of a dominant-negative TcRjl construct (TcRjlS37N) displays a significative growth phenotype in reduced serum medium. Remarkably, overexpression of TcRjl inhibits differentiation of epimastigotes to trypomastigote forms and promotes the accumulation of intermediate differentiation stages. Our data suggest that TcRjl might play a role in the control of the parasite growth and differentiation.

Arfs (ADP-ribosylation factors) are conserved GTP-binding proteins involved in the control of coatomers assembling in budding vesicles in the eukaryotic secretory pathway and during some endocytic events. Here, we describe the gene for an Arf-homologue from the unicellular kinetoplastid parasite Trypanosoma cruzi, named TcArf1. TcArf1 is present in a discrete copy number in the T. cruzi genome and is expressed as a 1-kb transcript in the three main life forms of the parasite. Increased mRNA expression in epimastigotes may correlate with abundant protein biosynthesis and endocytosis in this stage.

The Brazilian strategy to overcome the spread of COVID-19 has been particularly criticized due to the lack of a national coordinating effort and an appropriate testing program. Here, a successful approach to control the spread of COVID-19 transmission is described by the engagement of public (university and governance) and private sectors (hospitals and oil companies) in Macaé, state of Rio de Janeiro, Brazil, a city known as the National Oil Capital. In 2020 between the 17th and 38th epidemiological week, over two percent of the 206,728 citizens were subjected to symptom analysis and RT-qPCR testing by the Federal University of Rio de Janeiro, with positive individuals being notified up to 48 h after swab collection. Geocodification and spatial cluster analysis were used to limit COVID-19 spreading in Macaé. Within the first semester after the outbreak of COVID-19 in Brazil, Macaé recorded 1.8% of fatalities associated with COVID-19 up to the 38th epidemiological week, which was at least five times lower than the state capital (10.6%). Overall, considering the successful experience of this joint effort of private and public engagement in Macaé, our data suggest that the development of a similar strategy countrywise could have contributed to a better control of the COVID-19 spread in Brazil. Quarantine decree by the local administration, comprehensive molecular testing coupled to scientific analysis of COVID-19 spreading, prevented the catastrophic consequences of the pandemic as seen in other populous cities within the state of Rio de Janeiro and elsewhere in Brazil.

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