Pentose phosphate metabolism in Leishmania mexicana.
The metabolism of pentose phosphates was studied in Leishmania mexicana promastigotes. Each of the enzymes of the classical pentose phosphate pathway (PPP) has been identified and specific activities measured. Functioning of the PPP was demonstrated in non-growing cells by measuring the evolution of 14CO2 from [1-14C]D-glucose and [6-14C]D-glucose under normal conditions and also under selective stimulation of the PPP by exposure to methylene blue. The proportion of glucose which passes through the PPP increases in the latter condition, thus suggesting a protective role against oxidant stress. The incorporation into nucleic acids of ribose 5-phosphate provided via either glucose or free ribose was also determined. Results indicate that the PPP enables glucose to serve as a source of ribose 5-phosphate in nucleotide biosynthesis. Moreover, free ribose is incorporated efficiently, implying the presence of a ribose uptake system and also of ribokinase. Ribose was shown to be accumulated by a carrier mediated process in L. mexicana promastigotes and ribokinase activity was also measured in these cells.
Maugeri
Dante Abel
DA
Instituto de Investigaciones Biotecnologicas, Universidad Nacional de General San Martin, 1650 San Martin, Buenos Aires, Argentina.
Cazzulo
Juan Jose
JJ
Burchmore
Richard J S
RJ
Barrett
Michael P
MP
Ogbunude
Patrick O J
PO
D000818:Animals; D001692:Biological Transport; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes; D002352:Carrier Proteins / Q000378:metabolism; D016054:DNA, Protozoan / Q000096:biosynthesis; D005947:Glucose / Q000378:metabolism; D006868:Hydrolysis; D007894:Leishmania mexicana / Q000201:enzymology / Q000378:metabolism*; D008751:Methylene Blue / Q000378:metabolism / Q000494:pharmacology; D009696:Nucleic Acids / Q000096:biosynthesis; D009705:Nucleosides / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D010427:Pentose Phosphate Pathway; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D016053:RNA, Protozoan / Q000096:biosynthesis; D012266:Ribose / Q000378:metabolism; D012267:Ribosemonophosphates / Q000378:metabolism
D002250:Carbon Radioisotopes; D002352:Carrier Proteins; D016054:DNA, Protozoan; D009696:Nucleic Acids; D009705:Nucleosides; D016053:RNA, Protozoan; D012267:Ribosemonophosphates; D002245:Carbon Dioxide; C031626:ribose-5-phosphate; D012266:Ribose; D017853:Phosphotransferases (Alcohol Group Acceptor); C022534:ribokinase; D005947:Glucose; D008751:Methylene Blue