title: A phagocytosis mutant of Entamoeba histolytica is less virulent due to deficient proteinase expression and release.
abstract: Cysteine proteinases are key virulence factors of Entamoeba histolytica that are released during the process of invasion. We used a chemical mutant of E. histolytica strain HM-1:IMSS, clone L6, which is deficient in virulence, phagocytosis, and cysteine proteinase activity to help define the mechanisms of cysteine proteinase release. All cysteine proteinase genes of wild type HM-1 were present in the L6 mutant genome, but three of the major expressed proteinases, ehcp1, ehcp2, and ehcp5 were both transcribed, translated, and released at lower levels in L6. We hypothesized that a central protein such as the calcium binding protein 1, EhCaBP1, which is required for both phagocytosis and exocytosis might be deficient in this mutant. We found that both mRNA and proteinase levels of EhCaBP1 were decreased in L6. These findings provide an important link between phagocytosis, passive release of multiple cysteine proteinases, and attenuated virulence of this E. histolytica mutant.
authors.affiliation: Departments of Pathology and Medicine, University of California, San Diego, CA 92103-8416, USA.
authors.forename: Ken K
authors.initials: KK
authors.lastname: Hirata
authors.forename: Xuchu
authors.initials: X
authors.lastname: Que
authors.forename: Samuel G
authors.initials: SG
authors.lastname: Melendez-Lopez
authors.forename: Anjan
authors.initials: A
authors.lastname: Debnath
authors.forename: Simona
authors.initials: S
authors.lastname: Myers
authors.forename: D Scott
authors.initials: DS
authors.lastname: Herdman
authors.forename: Esther
authors.initials: E
authors.lastname: Orozco
authors.forename: Alok
authors.initials: A
authors.lastname: Bhattacharya
authors.forename: James H
authors.initials: JH
authors.lastname: McKerrow
authors.forename: Sharon L
authors.initials: SL
authors.lastname: Reed
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D004748:Entamoeba histolytica / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity*; D004797:Enzyme-Linked Immunosorbent Assay; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics*; D046228:Microarray Analysis; D008863:Microspheres; D009154:Mutation; D010587:Phagocytosis / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D016053:RNA, Protozoan / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics / Q000502:physiology; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D002135:Calcium-Binding Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D037521:Virulence Factors; D003546:Cysteine Endopeptidases; C085577:Ca2+-binding protein-1