Channeling of carbamoyl phosphate to the pyrimidine and arginine biosynthetic pathways in the deep sea hyperthermophilic archaeon Pyrococcus abyssi. Export

@article{citeulike:3736704, abstract = {The kinetics of the coupled reactions between carbamoyl-phosphate synthetase (CPSase) and both aspartate transcarbamoylase (ATCase) and ornithine transcarbamoylase (OTCase) from the deep sea hyperthermophilic archaeon Pyrococcus abyssi demonstrate the existence of carbamoyl phosphate channeling in both the pyrimidine and arginine biosynthetic pathways. Isotopic dilution experiments and coupled reaction kinetics analyzed within the context of the formalism proposed by Ov\'{a}di et al. (Ov\'{a}di, J., Tompa, P., Vertessy, B., Orosz, F., Keleti, T., and Welch, G. R. (1989) Biochem. J. 257, 187-190) are consistent with a partial channeling of the intermediate at 37 degrees C, but channeling efficiency increases dramatically at elevated temperatures. There is no preferential partitioning of carbamoyl phosphate between the arginine and pyrimidine biosynthetic pathways. Gel filtration chromatography at high and low temperature and in the presence and absence of substrates did not reveal stable complexes between P. abyssi CPSase and either ATCase or OTCase. Thus, channeling must occur during the dynamic association of coupled enzymes pairs. The interaction of CPSase-ATCase was further demonstrated by the unexpectedly weak inhibition of the coupled reaction by the bisubstrate analog, N-(phosphonacetyl)-L-aspartate (PALA). The anomalous effect of PALA suggests that, in the coupled reaction, the effective concentration of carbamoyl phosphate in the vicinity of the ATCase active site is 96-fold higher than the concentration in the bulk phase. Channeling probably plays an essential role in protecting this very unstable intermediate of metabolic pathways performing at extreme temperatures.}, author = {Purcarea, C. and Evans, D. R. and Herv\'{e}, G.}, citeulike-article-id = {3736704}, citeulike-linkout-0 = {http://view.ncbi.nlm.nih.gov/pubmed/10037695}, citeulike-linkout-1 = {http://www.hubmed.org/display.cgi?uids=10037695}, day = {5}, issn = {0021-9258}, journal = {The Journal of biological chemistry}, keywords = {abyssi, carbamoyl, phosphate, pyrococcus}, month = {March}, number = {10}, pages = {6122--6129}, posted-at = {2008-12-02 18:43:19}, priority = {2}, title = {Channeling of carbamoyl phosphate to the pyrimidine and arginine biosynthetic pathways in the deep sea hyperthermophilic archaeon Pyrococcus abyssi.}, url = {http://view.ncbi.nlm.nih.gov/pubmed/10037695}, volume = {274}, year = {1999} }

TY - JOUR ID - citeulike:3736704 L3 - citeulike-article-id:3736704 N2 - The kinetics of the coupled reactions between carbamoyl-phosphate synthetase (CPSase) and both aspartate transcarbamoylase (ATCase) and ornithine transcarbamoylase (OTCase) from the deep sea hyperthermophilic archaeon Pyrococcus abyssi demonstrate the existence of carbamoyl phosphate channeling in both the pyrimidine and arginine biosynthetic pathways. Isotopic dilution experiments and coupled reaction kinetics analyzed within the context of the formalism proposed by Ovádi et al. (Ovádi, J., Tompa, P., Vertessy, B., Orosz, F., Keleti, T., and Welch, G. R. (1989) Biochem. J. 257, 187-190) are consistent with a partial channeling of the intermediate at 37 degrees C, but channeling efficiency increases dramatically at elevated temperatures. There is no preferential partitioning of carbamoyl phosphate between the arginine and pyrimidine biosynthetic pathways. Gel filtration chromatography at high and low temperature and in the presence and absence of substrates did not reveal stable complexes between P. abyssi CPSase and either ATCase or OTCase. Thus, channeling must occur during the dynamic association of coupled enzymes pairs. The interaction of CPSase-ATCase was further demonstrated by the unexpectedly weak inhibition of the coupled reaction by the bisubstrate analog, N-(phosphonacetyl)-L-aspartate (PALA). The anomalous effect of PALA suggests that, in the coupled reaction, the effective concentration of carbamoyl phosphate in the vicinity of the ATCase active site is 96-fold higher than the concentration in the bulk phase. Channeling probably plays an essential role in protecting this very unstable intermediate of metabolic pathways performing at extreme temperatures. IS - 10 JF - The Journal of biological chemistry SN - 0021-9258 EP - 6129 TI - Channeling of carbamoyl phosphate to the pyrimidine and arginine biosynthetic pathways in the deep sea hyperthermophilic archaeon Pyrococcus abyssi. VL - 274 SP - 6122 KW - abyssi KW - carbamoyl KW - phosphate KW - pyrococcus AU - Purcarea, C AU - Evans, DR AU - Hervé, G PY - 1999/03/05/ UR - http://view.ncbi.nlm.nih.gov/pubmed/10037695 ER -