• Title/Summary/Keyword: amoeba

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Pepstatin- Insensitive Carboxyl Proteinase: A Biochemical Marker for Late Lysosomes in Amoeba proteus

  • Hae Kyung Kwon;HyeonJung Kim;Tae In Ahn
    • Animal cells and systems
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    • v.3 no.2
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    • pp.221-228
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    • 1999

  • In order to find a biochemical marker for late Iysosomes, we characterized two cDNAs which were cloned by using a monoclonal antibody (mAb) against Iysosomes in Amoeba proteus as a probe. The two cDNAs, a 1.3-kb cDNA in pBSK-Iys45 and a 1.6-kb cDNA in pBSK-Iys60, were found to encode proteins homologous to pepstatin-insensitive carboxyl proteinases (PICPs). E. coli transformed with pBSK-Iys45 produced two immunopositive polypeptides (45 and 43 kDa) and the cDNA in 1274 bases encoded a 44,733-Da protein (Lys45) of 420 amino acids containing one site for a core oligosaccharide. On the other hand, E. coli transformed with pBSK-Iys60 produced several polypeptides (64, 54, 45, 41, and 37 kDa) reacting with the mAb. The cDNA contained 1629 bases and encoded a 59,231-Da protein (Lys60) of 530 amino acids containing two sites for asparagine-linked core oligosaccharides. These two cDNAs showed identities of 60.3% in nucleotide sequences and 23.6% in amino acid sequences. Lys45 and Lys60 appeared to share XXEFQK as a common antigenic domain. The amino acid sequence of the Lys45 protein showed 17.4% identity and 40.9% similarity to that of PICP from Pseudomonas sp. 101. On the other hand, Lys60 showed a 24.3% identity and 51.9% similarity with human Iysosomal PICP in the amino acid sequence. A putative active center for serine protease, GTS＊xxxxxFxG, was found to be conserved among PICP homologues. The two PICPs are the first reported enzymatic markers for late Iysosomes.

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Natural occurrence of Mycobacterium as an endosymbiont of Acanthamoeba isolated from a contact lens storage case

  • Yu, Hak-Sun;Jeong, Hae-Jin;Hong, Yeon-Chul;Seol, Seong-Yong;Chung, Dong-Il;Kong, Hyun-Hee
    • Parasites, Hosts and Diseases
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    • v.45 no.1 s.141
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    • pp.11-18
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    • 2007

  • Recent in vitro studies have revealed that a certain Mycobacterium can survive and multiply within free-living amoebae. It is believed that protozoans function as host cells for the intracellular replication and evasion of Mycobacterium spp. under harmful conditions. In this study, we describe the isolation and characterization of a bacterium naturally observed within an amoeba isolate acquired from a contact lens storage case. The bacterium multi-plied within Acanthamoeba, but exerted no cytopathic effects on the amoeba during a 6-year amoebic culture. Trasnmission electron microscopy showed that the bacteria were randomly distributed within the cytoplasm of trophozoites and cysts of Acanthamoeba. On the basis of the results of 18S rRNA gene analysis, the amoeba was identified as A. lugdunensis. A 16S rRNA gene analysis placed this bacterium within the genus Mycobacterium. The bacterium evidenced positive reactivity for acid-fast and fluorescent acid-fast stains. The bacterium was capable of growth on the Middlebrook 7H11-Mycobacterium-specific agar. The identification and characterization of bacterial endosymbionts of free-living protozoa bears significant implications for our understanding of the ecology and the identification of other atypical mycobacterial pathogens.

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Amoebic PI3K and PKC Is Required for Jurkat T Cell Death Induced by Entamoeba histolytica

  • Lee, Young Ah;Kim, Kyeong Ah;Min, Arim;Shin, Myeong Heon
    • Parasites, Hosts and Diseases
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    • v.52 no.4
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    • pp.355-365
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    • 2014

  • The enteric protozoan parasite Entamoeba histolytica is the causative agent of human amebiasis. During infection, adherence of E. histolytica through Gal/GalNAc lectin on the surface of the amoeba can induce caspase-3-dependent or -independent host cell death. Phosphorylinositol 3-kinase (PI3K) and protein kinase C (PKC) in E. histolytica play an important function in the adhesion, killing, or phagocytosis of target cells. In this study, we examined the role of amoebic PI3K and PKC in amoeba-induced apoptotic cell death in Jurkat T cells. When Jurkat T cells were incubated with E. histolytica trophozoites, phosphatidylserine (PS) externalization and DNA fragmentation in Jurkat cells were markedly increased compared to those of cells incubated with medium alone. However, when amoebae were pretreated with a PI3K inhibitor, wortmannin before being incubated with E. histolytica, E. histolytica-induced PS externalization and DNA fragmentation in Jurkat cells were significantly reduced compared to results for amoebae pretreated with DMSO. In addition, pretreatment of amoebae with a PKC inhibitor, staurosporine strongly inhibited Jurkat T cell death. However, E. histolytica-induced cleavage of caspase-3, -6, and -7 were not inhibited by pretreatment of amoebae with wortmannin or staurosporin. In addition, we found that amoebic PI3K and PKC have an important role on amoeba adhesion to host compartment. These results suggest that amebic PI3K and PKC activation may play an important role in caspase-independent cell death in Entamoeba-induced apoptosis.

  • https://doi.org/10.3347/kjp.2014.52.4.355 인용 PDF KSCI