MOLECULAR ANALYSIS OF PHOSPHOGLYCERATE KINASE IN TRYPANOPLASMA-BORRELI AND THE EVOLUTION OF THIS ENZYME IN KINETOPLASTIDA

In the protozoan kinetoplastid organism Trypanoplasma borreli, phospho glycerate kinase (PGK) activity was found in two different cell compar tments: 80% in the cytosol and 20% in peroxisome-like organelles calle d glycosomes. However, only one functional pgk gene could be detected, in addition to a pseudo-pgk gene. No short-range linkage could be est ablished between these two genes, although they are presumably present on the same chromosome. The intact gene codes for a polypeptide of 41 1 amino acids, with a C-terminal extension of four residues, -VAKF, a sequence with probably a low targeting efficiency for glycosomes. The calculated net charge and molecular mass of the encoded polypeptide ar e +13 and 44230 Da, respectively. In other Kinetoplastida, different t andemly arranged genes code for distinct PGK isoenzymes in glycosomes and cytosol. By comparison of the pgk gene organization, and a phyloge netic analysis, we have traced a plausible scenario of the evolution o f the PGK isoenzymes in these organisms and of the enzymes' intracellu lar compartmentation. (C) 1998 Elsevier Science B.V. All rights reserv ed.