Unusual gene organization in the protozoan parasite Entamoeba histolytica.
We have analyzed three independent genomic loci of the protozoan parasite Entamoeba histolytica that contain coding regions for the iron-containing superoxide dismutase, the pore-forming peptide, and the galactose-inhibitable lectin. All of the three structural genes were found to be closely linked unidirectionally to other coding sequences. The intergenic regions did not exceed 1,350 nucleotides. Nuclear run-on data demonstrated that at least the galactose-inhibitable lectin gene is transcribed in a monocistronic fashion. Comparison of the genomic sequences described here with several others reported previously for E. histolytica revealed a number of invariable peculiarities for the gene organization of this parasite: (i) Coding sequences are not interrupted by introns; (ii) 5' untranslated regions are rather short and transcription starts at the consensus sequences ATTCA or ATCA; (iii) an unusual TATA-motif is located about 30 nucleotides upstream of the start of transcription and comprises the sequence TATTTAAA, which reveals protein binding activity as determined by gel retardation assays; (iv) the conserved pentanucleotide motif TAA/TTT is found within the relatively short 3' untranslated regions and functions putatively as the transcription termination signal; and (v) a stretch of up to 12 pyrmidine residues is located at the end of transcribed sequences.
Bruchhaus
I
I
Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
Leippe
M
M
Lioutas
C
C
Tannich
E
E
D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D016054:DNA, Protozoan; D004748:Entamoeba histolytica / Q000235:genetics*; D017125:Genes, Protozoan; D007473:Ion Channels; D037102:Lectins; D008562:Membrane Glycoproteins / Q000235:genetics; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D015800:Protozoan Proteins / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics
D016054:DNA, Protozoan; D007473:Ion Channels; D037102:Lectins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D015800:Protozoan Proteins; C041670:amoebapore proteins, protozoan; C052452:galactose inhibitable adherence protein, Entamoeba histolytica; D013482:Superoxide Dismutase