A family of transcripts (K2) of Entamoeba histolytica contains polymorphic repetitive regions with highly conserved elements.
Sera from patients with invasive amebiasis were used to identify a cDNA clone (K2p-1) encoding a commonly recognized, repeat-containing antigen of the pathogenic Entamoeba histolytica HM-1:IMSS. K2p-1 was used to isolate 3 cDNA clones (K2 clones); one K2p-1 related clone from the same pathogenic E. histolytica strain and 2 from the nonpathogenic E. histolytica strain SAW-142. The nucleotide sequence and predicted amino acid sequence revealed a closely related family of transcripts differing mainly in the extent and arrangement of an internal region consisting of tandemly arranged repetitive elements. The repetitive units encoding either 12 or 8 amino acids were found to be highly conserved in all the K2 clones analyzed so far, suggesting that the repeat motifs perform functions common to both pathogenic and nonpathogenic E. histolytica. The genomic organization of the K2 genes was different when compared in pathogenic and nonpathogenic E. histolytica and may therefore be used to discriminate between pathogenic and nonpathogenic E. histolytica strains.
Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
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Köhler
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Tannich
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D016054:DNA, Protozoan / Q000235:genetics*; D004748:Entamoeba histolytica / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D017125:Genes, Protozoan; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics; D011110:Polymorphism, Genetic; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics
D000953:Antigens, Protozoan; D016054:DNA, Protozoan; D009842:Oligopeptides