Characterization of two long vesicle-associated membrane proteins or longins genes from Entamoeba histolytica.

Background: This study characterizes two long vesicle-associated membrane protein (VAMP) genes (SYBL-1 and SYBL-2) obtained from DNA of Entamoeba histolytica by PCR amplification. (Nucleotide sequences of the Entamoeba histolytica SYBL-1 and SYBL-2 genes appear in the GeneBank under accession numbers AY256852 and AY309014.)

Methods: The two cDNA products include one of 663 bp with sequence of 220 deduced amino acids, and a second of 693 bp with 230 deduced amino acid residues. Both products possess corresponding sequences for longin domain at N-terminus, a soluble N-ethylmaleimide-sensitive factor [NSF] attachment protein receptor (SNARE) coiled-coil region, a transmembrane domain (TM), and an intravesicular tail C-terminal, characteristics of all long VAMPs or longins. The current study identified presence of deduced peptide bonds in SYBL-1 and -2, which indicates that these two long VAMPs from E. histolytica could be appropriate substrates for zinc endopeptidases from tetanus and botulinum neurotoxins with specific activity toward neuronal synaptobrevins.

Results: Alignment by Basic Local Alignment Search Tool (BLAST) of deduced amino-acid sequence of long VAMPs genes SYBL-1 and -2 showed identity of between 20 and 40% with Caenorhabditis elegans, Dictyostelium discoideum, Drosophila melanogaster, Arabidopsis thaliana, Mus musculus, Homo sapiens, and Plasmodium falciparum.

Conclusions: It is possible that these two putative transport proteins are involved in endocytosis/exocytosis during a biological membrane fusion process, which may make them suitable candidates as targets for new drugs. According to published data, this is the first time that two such genes have been isolated from E. histolytica.