Entamoeba histolytica and Entamoeba dispar: differences in numbers and expression of cysteine proteinase genes

Abstract

In order to identify molecules that might be responsible for the difference in pathogenicity between the two closely related protozoan parasites Entamoeba histolytica and Entamoeba dispar, we focussed on cysteine proteinases because this class of enzymes has been considered important for pathogenic tissue destruction. By screening a genomic library derived from an E. histolytica isolate, a total of six distinct genes (ehcp1-ehcp6) encoding typical prepro-forms of cysteine proteinases were identified which differed from each other by 40% to 85% of their nucleotide sequences. Three of these genes, ehcp1, ehcp2, and ehcp5, which exhibited high levels of expression, were found to be responsible for approximately 90% of cysteine proteinase transcripts, whereas the remaining three were either not or only marginally expressed. Expression of the different genes directly correlated with the level of activity of the respective enzymes in trophozoite lysates. Purification of the enzymes and N-terminal sequencing revealed that virtually all cysteine proteinase activity of E. histolytica can be attributed to three enzymes namely EhCP1, EhCP2 and EhCP5. Southern blot analysis indicated that just two of these abundantly expressed genes are missing in E. dispar. On the other hand, genes analogous to four of the six genes identified in E. histolytica were found to be present in E. dispar, but only two of these are expressed within the trophozoite stage.

Identification and Biochemical Characterization of Unique Secretory Nucleases of the Human Enteric Pathogen, Entamoeba histolytica

“…Furthermore, several Entamoeba cell surface and secreted proteins (i.e. Gal/GalNac lectin, amebapores, and cysteine proteases) contain typical signal sequences similar to higher eukaryotes for targeting through the ER and Golgi (52)(53)(54). In fact, the secretion of cysteine proteases is essential for the pathogenicity of E. histolytica (55)(56)(57).…”

A Retromerlike Complex Is a Novel Rab7 Effector That Is Involved in the Transport of the Virulence Factor Cysteine Protease in the Enteric Protozoan ParasiteEntamoeba histolytica

“…E. histolytica reveals only two developmental stages, dividing trophozoite and dormant cyst stage, in its simplified life cycle (Ravdin, 1988 Tannich, personal communication), is currently considered to be primarily responsible for the pathogenesis of E. histolytica as genes encoding certain isotypes, i.e., CP1 and CP5, are either absent or degenerated in a closely-related but nonpathogenic E. dispar species (Bruchhaus et al, 1996;Willhoeft et al, 1999). In addition, overexpression of CP2 caused augmentation of monolayer destruction, but no change in liver abscess formation (Hellberg et al, 2001).…”

“…Vesicular trafficking plays an This article was published online ahead of print in MBC in Press (http://www.molbiolcell.org/cgi/doi/10.1091/mbc.E05-04 -0283) on August 24, 2005. indispensable role for this organisms in nutrient uptake by ingestion and degradation of microorganisms in the large intestine, and also in secretion of cyto-and histolytic degradative proteins including cysteine proteases (CP; Que and Reed, 2000) and pore forming peptides (amoebapore: AP; Zhang et al, 2004), both of which have been implicated for colonization in mammalian tissues and evasion from host immune system. CP, consisting of Ͼ30 members of the gene family (Bruchhaus et al, 2003;Tannich, personal communication), is currently considered to be primarily responsible for the pathogenesis of E. histolytica as genes encoding certain isotypes, i.e., CP1 and CP5, are either absent or degenerated in a closely-related but nonpathogenic E. dispar species (Bruchhaus et al, 1996;Willhoeft et al, 1999). In addition, overexpression of CP2 caused augmentation of monolayer destruction, but no change in liver abscess formation (Hellberg et al, 2001).…”

A Novel Entamoeba histolytica Cysteine Proteinase, EhCP4, Is Key for Invasive Amebiasis and a Therapeutic Target

“…In axenically cultured E. histolytica trophozoites, the papain family members EhCP1, EhCP2, and EhCP5 account for ϳ90% of the total cysteine protease activity (19). However, the expression of EhCP genes in cultured trophozoites differs from those in vivo.…”