Chemistry: molecular biology and microbiology – Enzyme – proenzyme; compositions thereof; process for... – Transferase other than ribonuclease
Reexamination Certificate
1990-07-16
2001-06-19
Murthy, Ponnathapuachuta (Department: 1652)
Chemistry: molecular biology and microbiology
Enzyme , proenzyme; compositions thereof; process for...
Transferase other than ribonuclease
C435S069100, C435S194000, C435S252330, C435S320100, C536S023200
Reexamination Certificate
active
06248577
ABSTRACT:
The control of malaria has proved elusive, and an estimated 60 million cases of the disease occur worldwide each year. Malaria is now on the increase throughout the tropics, especially in the Indian subcontinent. In 1984, 1,016 cases of malaria were reported in the United States and of these, 26 percent were caused by
Plasmodium falciparum
, the most lethal of the four malarial parasites which infect humans.
The disease caused by
Plasmodium falciparum
differs from that caused by the other forms in a number of important respects, largely by the capacity of this species of protozoa to obstruct microcirculation in various organs and the high intensity—many times the number of parasitized red blood cells number in excess of 10 percent—of parasitemia.
Plasmodium falciparum
undergoes three cycles of development in its vertabrate host and elicits stage-specific immune responses. This stage-specific aspect of the immune response has made it difficult to isolate antigens that would be useful in developing a vaccine against malaria. Thus, the infection is currently being treated by combination chemotherapy.
Recent increases in the frequency of chloroquine and pyrimethamine resistant malarial infections, specifically infection with
P. falciparum
, have emphasized the urgent need for development of new chemotherapeutic agents to combat this disease. However, a more efficient and rational approach to the development of chemotherapeutic agents is to exploit defined differences in host and parasite metabolism. These differences can then become the basis upon which inhibitors specific to parasite enzymes may be developed and utilized as specific agents in the therapeutic treatment of the infection.
The choice of a potential target enzyme for malarial parasites is suggested, under the approach taken by the present invention, by the inability of the parasite to synthesize purines de novo during the intra-erythoocytic stages of their life cycle in their mammalian host. The parasite therefore relies upon the host to provide the necessary free pre-formed purines to satisfy its requirement. One important enzyme involved in the salvage of purines from Plasmodium-infected red blood cells is hypoxanthine-guanine phosphoribosyltransferase (HGPRT). HGPRT is a tetrameric enzyme in man which catalyzes the phosphoribosylation of hypoxanthine and guanine to form inosine monophosphate and guanosine monophosphate, in the presence of 5′-phosphoribosyl-1-pyrophosphate. In Plasmodium, the enzyme appears as a dimer with a weight of 52 kD.
The activity of this enzyme is present in
P. falciparum
blood stage parasites at high levels, and prior experimentation [see Microbiological Reviews 43(4): 453 (1979)] with Plasmodium sp. has indicated that the salvage of hypoxanthine is an essential key element in parasitic nucleic acid synthesis as the only significant source of purines. A better understanding of the essential nature of the HGPRT enzyme in the purine nucleotide salvage in
Plasmodium falciparum
can be had with an examination of the following schematic pathway indicating the salvage pathways in this organism:
NO.
ENZYME
1
ADENOSINE KINASE
2
APRT
3
ADENOSINE DEAMINASE
4
HGPRT
5
PURINE NUCLEOSIDE PHOSPHORYLASE
6
AMP DEAMINASE
7
GUANYLATE REDUCTASE
8
ADENYLOSUCCINATE SYNTHETASE
9
ADENYLOSUCCINATE LYASE
10
IMP DEHYDROGENASE
11
GMP SYNTHETASE
12
IMP NUCLEOTIDASE
As can be understood from this examination, the reliance that the parasite has on its own HGPRT activity during its intra-erythrocytic stages makes this enzyme a potential target for potential therapeutic activity in the treatment of malarial disease. If HGPRT can be inhibited or removed from the parasite's purine nucleotide salvage pathway, the parasite will become, effectively, weakened to an extent wherein chemotherapeutic agents or the host's own immune responses will be able to more efficiently combat the infection.
Accordingly, it is the purpose of the present invention to describe the cloning and isolation of HGPRT cDNA containing an open reading frame corresponding to the HGPRT of
Plasmodium falciparum
, present the complete nucleotide sequence of the
Plasmodium falciparum
HGPRT Dral/Pstl cDNA fragment, and demonstrate the expression of this gene product in an
E. coli
strain deficient in purine salvage.
REFERENCES:
King, A., et al, 1987, Nucleic Acids Research 15(24): 10469-10481.*
Marsh, P., 1986, Nucleic Acids Research 14(8): 3603.*
Kalle, G., et al., 1961, Biochimica et Biophysica Acta 53: 166-173.*
McIntyre, P., et al., 1987, International Journal of Parasitology 17(1): 59-68.*
Remy, C.N., et al., (1957) Journal of Biological Chemistry 228: 325-338.*
Vasantha Kumar, G., et al., 1989, Nucleic Acids Research, 17(20): 8382.*
Dayhoff, M.O., Ed., 1970 Atlas of Protein Sequence and Structure, vol. 5, pp. 101-110, (Barlow & Dayhoff) Nat'l. Biomedical Research Foundation.*
Smith, D.B., et al., 1988, Molecular and Boichemical Parasitology 27: 249-246.*
Sheppard, H.W., et al., 1986, Molecular and Biochemical Parasitology 19: 35-43.*
Vasanthakumar, G., et al., 1989, The Journal of Cellular Biochemistry, Supplement E, p. 125, Abstract 0 485.*
Craig, S.P., et al., 1988, Nucleic Acids Research, 16(14): 7087-7100.*
Fujimori. S., et al., 1988, Human Genetics, 79: 39-43.*
Fenwick, R.G., et al., 1984, Somatic Cell and Molecular Genetics, 10(1): 71-84.*
Singh, G., et al., 1988, Cancer Chemo Therapy and Pharmacology, 22: 191-196.*
Enea, V., et al., 1984, “DNA cloning of Plasmodium falciparum circumsporozoite gene: amino acid sequence of repetitive epitope”, vol. 225, pp. 628-630.*
Hyde, J. E., et al., 1984, “Characterization and translation studies of messenger RNA from the human malaria parasite Plasmodium falciparum and construction of a cDNA library”; Molecular and Biochemical Parasitology, vol. 10, pp. 269-285.*
Sullivan, M. A., et al., 1987, “Isolation and characterization of the gene encoding hypoxanthine-guanine phosphoribosyltransferase from Plasmodium falciparum”, in Molecular Strategiesof Parasitic Invasion, Agabian, N., et al., Eds., pp. 575-584.*
Shahabuddin, M., et al., 1990, “The gene for hypoxanthine phosphoribosyltransferase of Plasmodium falciparum complements a bacterial HPT mutation”, Molcular and Biochemical Parasitology, vol. 41, pp. 281-288.*
Cappai, R., et al., 1992, “The Plasmodium falciparum hypoxanthine-guanine gene has phosphoribosyltransferase phosphoribosyltransferase gene has a 5' upstream intorn”, Molecular and Biochemical Parasitology, vol. 54, pp. 117-120.*
Allen, T. E., et al., 1993, “Cloning and expression of the hypoxanthine-guanine phosphoribosyltransferase gene from Trypanosoma brucei”, Nucleic Acids Research, vol. 21, pp. 5431-5438.*
Allen, T. E., et al., 1994, “Molecular characterization and overexpression of the hypoxanthine-guanine phosphoribosyltransferase gene from Trypanosoma cruzii”, Molecular and Biochemical Parasitology, vol. 65, pp. 233-245.*
Keough, D. T., et al., 1998, “Expression and properties of recombinant P. falciparum hypoxanthine-guanine phosphoribosyltransferase”, in Purine and Pyrimidine Metabolism in Man IX, Griesmacher et al., Eds., Plenum Press, pp. 735-739.*
Keough, D. T., et al., 1999, “Purfication and characterization of Plasmodium falciparum hypoxanthine-guanine phosphoribosyltransferase and comparison with the human enzyme”, Molecular and Biochemical Parasitology, vol. 98, pp. 735-739.*
Balaram, H., et al., 1999, “Tinkering with enzymes”, Journal of the Indian Institute for Science, vol. 79, pp. 49-60.
Montgomery John A.
Vasanthakumar Geetha
Moore William W.
Murthy Ponnathapuachuta
Needle & Rosenberg P.C.
Southern Research Institute
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