Allosteric regulation accompanied by oligomeric state changes of Trypanosoma brucei GMP reductase through cystathionine-β-synthase domain.

Guanosine 5'-monophosphate reductase (GMPR) is involved in the purine salvage pathway and is conserved throughout evolution. Nonetheless, the GMPR of Trypanosoma brucei (TbGMPR) includes a unique structure known as the cystathionine-β-synthase (CBS) domain, though the role of this domain is not fully understood. Here, we show that guanine and adenine nucleotides exert positive and negative effects, respectively, on TbGMPR activity by binding allosterically to the CBS domain.

Novel Characteristics of Trypanosoma brucei Guanosine 5'-monophosphate Reductase Distinct from Host Animals.

The metabolic pathway of purine nucleotides in parasitic protozoa is a potent drug target for treatment of parasitemia. Guanosine 5'-monophosphate reductase (GMPR), which catalyzes the deamination of guanosine 5'-monophosphate (GMP) to inosine 5'-monophosphate (IMP), plays an important role in the interconversion of purine nucleotides to maintain the intracellular balance of their concentration. However, only a few studies on protozoan GMPR have been reported at present.

Late stage infection in sleeping sickness.

At the turn of the 19(th) century, trypanosomes were identified as the causative agent of sleeping sickness and their presence within the cerebrospinal fluid of late stage sleeping sickness patients was described. However, no definitive proof of how the parasites reach the brain has been presented so far. Analyzing electron micrographs prepared from rodent brains more than 20 days after infection, we present here conclusive evidence that the parasites first enter the brain via the choroid plexus from where they penetrate the epithelial cell layer to reach the ventricular system.

New anti-malarial phenylpropanoid conjugated iridoids from Morinda morindoides.

A new phenylpropanoid conjugated iridoid together with four known congeners was isolated from Morinda morindoides, used for the therapy of malaria traditionally in some African countries, as anti-malarial principles through bioassay-guided separation. Furthermore, their absolute stereostructures were unambiguously established by a combination of modified Mosher's method and chemical correlation.

Molecular basis for prostaglandin production in hosts and parasites.

Prostaglandins (PGs) comprise a family of structurally related bioactive lipid mediators that are involved in various symptoms associated with parasitic diseases. The molecular mechanisms of PG biosynthesis in animals have been studied extensively. Currently, several lines of evidence link their production with parasites.

Prostaglandin production from arachidonic acid and evidence for a 9,11-endoperoxide prostaglandin H2 reductase in Leishmania.

Lysates of Leishmania promastigotes can metabolise arachidonic acid to prostaglandins. Prostaglandin production was heat sensitive and not inhibited by aspirin or indomethacin. We cloned and sequenced the cDNA of Leishmania major, Leishmania donovani, and Leishmania tropica prostaglandin F(2alpha) synthase, and overexpressed their respective 34-kDa recombinant proteins that catalyse the reduction of 9,11-endoperoxide PGH(2) to PGF(2alpha).

Crystallization and preliminary X-ray crystallographic studies of Trypanosoma brucei prostaglandin F(2 alpha) synthase.

Prostaglandin F(2 alpha) is a potent mediator of various physiological and pathological processes. Trypanosoma brucei prostaglandin F(2 alpha) synthase (TbPGFS) catalyzes the NADPH-dependent reduction of 9,11-endoperoxide PGH(2) to PGF(2 alpha), and could thus be involved in the elevation of the PGF(2 alpha) concentration during African trypanosomiasis. In the present report, the purification and crystallization of recombinant TbPGFS are described.

Prostaglandin production from arachidonic acid and evidence for a 9,11-endoperoxide prostaglandin H2 reductase in Leishmania.

Lysates of Leishmania promastigotes can metabolise arachidonic acid to prostaglandins. Prostaglandin production was heat sensitive and not inhibited by aspirin or indomethacin. We cloned and sequenced the cDNA of Leishmania major, Leishmania donovani, and Leishmania tropica prostaglandin F(2alpha) synthase, and overexpressed their respective 34-kDa recombinant proteins that catalyse the reduction of 9,11-endoperoxide PGH(2) to PGF(2alpha).

A key role for old yellow enzyme in the metabolism of drugs by Trypanosoma cruzi.

Trypanosoma cruzi is the etiological agent of Chagas' disease. So far, first choice anti-chagasic drugs in use have been shown to have undesirable side effects in addition to the emergence of parasite resistance and the lack of prospect for vaccine against T. cruzi infection.

Immunohistochemical localization of microsomal PGE synthase-1 and cyclooxygenases in male mouse reproductive organs.

We investigated the tissue distribution and cellular localization of microsomal PGE synthase-1 (mPGES-1) and cyclooxygenase (COX)-1 and -2 in the male mouse reproductive organs. Northern blotting revealed that the mPGES-1 mRNA was expressed intensely in the epididymis and weakly in the lung, spleen, skin, kidney, colon, and brain. In the male reproductive tract, the expression of mPGES-1 increased from the testis to the cauda epididymis and was highest in the vas deferens when examined by Northern blotting, RT-PCR, and Western blotting.

Biochemical characterization of mouse microsomal prostaglandin E synthase-1 and its colocalization with cyclooxygenase-2 in peritoneal macrophages.

We cloned the cDNA for mouse microsomal prostaglandin (PG) E synthase-1 (mPGES-1) and expressed the recombinant enzyme in Escherichia coli. The membrane fraction containing recombinant mPGES-1 catalyzed the isomerization of PGH2 to PGE2 in the presence of GSH with K(m) values of 130 microM for PGH2 and 37 microM for GSH, a turnover number of 600 min(-1), and a k(cat)/K(m) ratio of 4.6 min(-1) microM(-1).