Cloning and bacterial expression of adenosine-5 '-triphosphate sulfurylasefrom the enteric protozoan parasite Entamoeba histolytica

A gene encoding adenosine-5'-triphosphate sulfurylase (AS) was cloned from the enteric protozoan parasite Entamoeba histolytica by polymerase chain re action using degenerate oligonucleotide primers corresponding to conserved regions of the protein from a variety of organisms. The deduced amino acid sequence of E. histolytica AS revealed a calculated molecular mass of 47925 Da and an unusual basic pi of 9.38. The amebic protein sequence showed 23- 48% identities with AS from bacteria, yeasts, fungi, plants, and animals wi th the highest identities being to Synechocystis sp. and Bacillus subtilis (48 and 44%, respectively). Four conserved blocks including putative sulfat e-binding and phosphate-binding regions were highly conserved in the E. his tolytica AS. The upstream region of the AS gene contained three conserved e lements reported for other E. histolytica genes. A recombinant E. histolyti ca AS revealed enzymatic activity, measured in both the forward and reverse directions. Expression of the E. histolytica AS complemented cysteine auxo trophy of the AS-deficient Escherichia coli strains. Genomic hybridization revealed that the AS gene exists as a single copy gene. In the literature, this is the first description of an AS gene in Protozoa. (C) 1998 Elsevier Science B.V. All rights reserved.