Stress-dependent expression of a polymorphic, charged antigen in the protozoan parasite Entamoeba histolytica.
We have identified a novel stress inducible gene, Ehssp1 in Entamoeba histolytica, the causative agent of amebiasis. Ehssp1 belongs to a polymorphic, multigene family and is present on multiple chromosomes. No homologue of this gene was found in the NCBI database. Sequence alignment of the multiple copies, and genomic PCR data restricted the polymorphism to the central region of the gene. This region contains a polypurine stretch that encodes a domain rich in acidic and basic amino acids. Under normal culture conditions only one copy of this multigene family is expressed, as observed by Northern blot and RT-PCR analysis. The size of this copy of the gene is 1,077 nucleotides, encoding a protein of 359 amino acids. The polymorphic domain in this copy is 64 nucleotides long. However, on exposure of cells to stress conditions such as heat shock or oxidative stress, multiple polymorphic copies of the gene are expressed, suggesting a possible role of this gene in adaptation of cells to stress conditions. The gene copy expressed under normal conditions, and the expression profile of cells under heat stress was identical in two different strains of E. histolytica tested. Interestingly, the extent of polymorphism in this gene was very less in E. dispar, a nonpathogenic sibling species of E. histolytica. Ehssp1 was found to be antigenic in invasive amebiasis patients.
Satish
S
S
School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
Bakre
Abhijeet A
AA
Bhattacharya
Sudha
S
Bhattacharya
Alok
A
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D016054:DNA, Protozoan / Q000235:genetics; D004748:Entamoeba histolytica / Q000235:genetics* / Q000254:growth & development / Q000276:immunology*; D015870:Gene Expression; D017125:Genes, Protozoan; D006358:Hot Temperature; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D000953:Antigens, Protozoan; D016054:DNA, Protozoan; D015800:Protozoan Proteins; D011994:Recombinant Proteins