The ubiquitous gp63-like metalloprotease from lower trypanosomatids: in the search for a function

Plant and insect trypanosomatids constitute the "lower trypanosomatids", which have been used routinely as laboratory models for biochemical and molecular studies because they are easily cultured under axenic conditions, and they contain homologues of virulence factors from the classic human trypanosomatid pathogens. Among the molecular factors that contribute to Leishmania spp. virulence and pathogenesis, the major surface protease, alternatively called MSP, PSP, leishmanolysin, EC 3.4.24.36 and gp63, is the most abundant surface protein of Leishmania promastigotes. A myriad of functions have been described for the gp63 from Leishmania spp. when the metacyclic promastigote is inside the mammalian host. However, less is known about the functions performed by this molecule in the invertebrate vector. Intriguingly, gp63 is predominantly expressed in the insect stage of Leishmania, and in all insect and plant trypanosomatids examined so far. The gp63 homologues found in lower trypanosomatids seem to play essential roles in the nutrition as well as in the interaction with the insect epithelial cells. Since excellent reviews were produced in the last decade regarding the roles played by proteases in the vertebrate hosts, we focused in the recent developments in our understanding of the biochemistry and cell biology of gp63-like proteins in lower trypanosomatids.

Tripanossomatídeos de insetos e de plantas são informalmente denominados de "tripanossomatídeos inferiores". Estes microrganismos são utilizados rotineiramente como modelos para estudos de bioquímica e de biologia molecular porque são facilmente cultivados sob condições axênicas e porque possuem homólogos aos fatores de virulência encontrados nos tripanossomatídeos que são patógenos humanos clássicos. Dentre os fatores moleculares que contribuem para a virulência e patogênese de Leishmania spp. destaca-se a principal protease de superfície, também conhecida como MSP, PSP, leishmanolisina, EC 3.4.24.36 e gp63, que é a proteína de superfície mais abundante encontrada nas formas promastigotas de Leishmania. Diversas funções foram descritas para a gp63 de Leishmania no hospedeiro vertebrado. Entretanto, pouco é conhecido sobre as funções desempenhadas por essa molécula no inseto vetor. Curiosamente, a gp63 é predominantemente expressa na forma evolutiva de Leishmania encontrada no inseto, e em todos os tripanossomatídeos de insetos e plantas analisados até o presente momento. Os homólogos da gp63 presentes nos tripanossomatídeos inferiores desempenham um papel essencial na nutrição assim como na interação com as células epiteliais do inseto. Uma vez que revisões de excelente qualidade foram produzidas na última década sobre a função de proteases nos hospedeiros vertebrados, nesta revisão nós abordamos os recentes progressos sobre os aspectos bioquímicos e as prováveis funções biológicas desempenhadas pelas proteínas homólogas à gp63 nos tripanossomatídeos inferiores.

Inflammatory effects of snake venom metalloproteinases

Metalloproteinases are abundant enzymes in crotaline and viperine snake venoms. They are relevant in the pathophysiology of envenomation, being responsible for local and systemic hemorrhage frequently observed in the victims. Snake venom metalloproteinases (SVMP) are zinc-dependent enzymes of varying molecular weights having multidomain organization. Some SVMP comprise only the proteinase domain, whereas others also contain a disintegrin-like domain, cysteine-rich, and lectin domains. They have strong structural similarities with both mammalian matrix metalloproteinases (MMP) and members of ADAMs (a disintegrin and metalloproteinase) group. Besides hemorrhage, snake venom metalloproteinase induce local myonecrosis, skin damage, and inflammatory reaction in experimental models. Local inflammation is an important characteristic of snakebite envenomations inflicted by viperine and crotaline snake species. Thus, in the recent years there is a growing effort to understand the mechanisms responsible for SVMP-induced inflammatory reaction and the structural determinants of this effect. This short review focuses the inflammatory effects evoked by SVMP.

Virulence factors of non-O1 non-O139 Vibrio cholerae isolated in Córdoba, Argentina / Factores de virulencia de Vibrio cholerae no-O1 no-O139 aislados en Córdoba, Argentina

V. cholerae non-O1 non-O139 serogroups isolated from clinical and environmental sources in Córdoba, Argentina, were analyzed for the presence and expression of virulence genes. Most of the strains studied contained the genes toxR and hlyA, but lacked ctxA, zot, ace, tcpA and stn. The culture supernatants were tested for hemolytic and cytotoxic activity. The enterotoxic potential of the strains was studied in a rabbit ileal loop assay and their genetic profiles were compared by PFGE. The environmental strains varied in their virulence phenotype and showed no-clonal relationships. The clinical strains were highly enterotoxic, hemolytic, proteolytic and showed indistinguishable PFGE profiles, although they differed in their cytotoxic activity. This is the first description, using cell culture and “in vivo” studies, of the virulence properties of non-O1 non-O139 V. cholerae from Argentina.

En este trabajo se analizó la presencia y expresión de genes de virulencia en V. cholerae no-O1 no-O139 de origen clínico y ambiental, aislados en Córdoba, Argentina. La mayoría de las cepas estudiadas contiene los genes toxR y hlyA, pero no ctxA, zot, ace, tcpA y stn. Se analizó la actividad hemolítica y citotóxica de estas cepas en los sobrenadantes de cultivo, así como su potencial enterotóxico en ensayos de asa ileal ligada de conejo. Además, los aislamientos fueron comparados por sus perfiles genéticos en PFGE. Las cepas del medio ambiente mostraron variación en su fenotipo de virulencia y no mostraron relación clonal. Las cepas clínicas fueron muy enterotóxicas, hemolíticas, proteolíticas y mostraron perfiles indistinguibles de PFGE, aunque mostraron diferencias en su actividad citotóxica. En este trabajo se describen por primera vez, utilizando ensayos de cultivo celular e “in vivo”, propiedades de virulencia de V. cholerae no-O1 no-O139 aislados en Argentina.