Homologous cysteine proteinases of pathogenic and nonpathogenic Entamoeba histolytica. Differences in structure and expression.
A cDNA clone derived from the gene encoding a cysteine proteinase of pathogenic Entamoeba histolytica was isolated using an antiserum to the purified enzyme. This clone was used to identify the homologous clone in a cDNA library from nonpathogenic E. histolytica. Sequence analysis and comparison of the predicted amino acid sequences revealed a sequence divergence of 16%. Southern blot analyses indicated that (i) pathogenic isolates may contain more genes coding for these or related enzymes than nonpathogenic isolates, (ii) the structure and organization of these genes are conserved within each group of amoebae, and (iii) none of the genes is found in both pathogenic and nonpathogenic E. histolytica, underlining the notion that the two groups are genetically distinct. Northern blot analyses suggested that the cysteine proteinase is expressed by pathogenic isolates in substantially higher amounts than by nonpathogenic isolates. Overexpression of this enzyme may be an important factor in the pathogenicity of E. histolytica.
Tannich
E
E
Bernhard Nocht Institute for Tropical Medicine, Hamburg, Federal Republic of Germany.
Scholze
H
H
Nickel
R
R
Horstmann
R D
RD
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D003546:Cysteine Endopeptidases / Q000235:genetics*; D004247:DNA / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D004748:Entamoeba histolytica / Q000201:enzymology* / Q000472:pathogenicity; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012313:RNA / Q000032:analysis; D012689:Sequence Homology, Nucleic Acid
D016054:DNA, Protozoan; D012313:RNA; D004247:DNA; D003546:Cysteine Endopeptidases