Abstract
Prenylated protein methyltransferase, an enzyme involved in the post-translational modification of many signalling proteins, has been characterized in a parasitic flagellated protozoan, Leishmania donovani. The activity of this enzyme was monitored by the methylation of an artificial substrate, an S-prenylated cysteine analogue, with S-adenosyl-L-[methyl-3H]methionine as methyl donor. More than 85% of the methyltransferase activity was associated with membranes. The enzyme methylates N-acetyl-S-trans, trans-farnesyl-L-cysteine and N-acetyl-S-all-trans-geranylgeranyl-L-cysteine, but N-acetyl-S-trans, trans-geranyl-L-cysteine only very weakly. In contrast with the enzyme from mammals, the leishmanial enzyme had a greater affinity for the farnesylated substrate than for the geranylgeranylated one. Activity in vitro was not modulated by cAMP, protein kinase C activator or guanosine 5'-[γ-thio]triphosphate. An analysis of the endo gene us substrates showed that the carboxymethylated proteins were also isoprenylated. The main carboxymethylated proteins have molecular masses of 95, 68, 55, 46, 34-23, 18 and less than 14 kDa. Treatment of cells with N-acetyl-S-trans, trans-farnesyl-L-cysteine decreased the carboxymethylation level, whereas treatment with guanosine 5'-[γ-thio]triphosphate increased the carboxymethylation of various proteins, particularly those of molecular masses 30-20 kDa.
Original language | English (US) |
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Pages (from-to) | 513-518 |
Number of pages | 6 |
Journal | Biochemical Journal |
Volume | 342 |
Issue number | 3 |
DOIs | |
State | Published - Sep 15 1999 |
Externally published | Yes |
Keywords
- Kinetoplastidae
- Leishmania donovani
- Promastigote
- Protozoans
- Sinefungin
ASJC Scopus subject areas
- Biochemistry
- Molecular Biology
- Cell Biology