ORGANIZATION, SEQUENCE AND STAGE-SPECIFIC EXPRESSION OF THE PHOSPHOGLYCERATE KINASE GENES OF LEISHMANIA-MEXICANA MEXICANA

In Leishmania mexicana two genes were detected coding for different is oforms of the glycolytic enzyme phosphoglycerate kinase. This situatio n contrasts with that observed in other Trypanosomatidae (Trypanosoma brucei, Trypanosoma congolense, Crithidia fasciculata) analyzed previo usly, which all contain three different genes coding for isoenzymes A, B and C, respectively. All attempts to detect in L. mexicana a type A PGK, or a gene encoding it, proved unsuccessful. We have cloned and c haracterized the genes PGKB and PGKC. They code for polypeptides of 41 6 and 478 amino acids with a molecular mass of 45146 and 51318 Da, res pectively. The two polypeptides are 99% identical. PGKC is characteriz ed by a 62 residue C-terminal extension with alternating stretches of hydrophobic and charged, mainly positive amino acids. As in other Tryp anosomatidae, PGKB is located in the cytosol, PGKC in the glycosomes. However, Leishmania mexicana distinguishes itself from other trypanoso matids by the simultaneous expression of these isoenzymes: approximate to 80% of PGK activity is found in the cytosol and 20% in the glycoso mes, both in promastigotes and in the amastigote-like form of the para site. (C) 1997 Elsevier Science B.V.