Vitamin B1 de novo synthesis in the human malaria parasite Plasmodium falciparum depends on external provision of 4-amino-5-hydroxymethyl-2-methylpyrimidine.
Vitamin B1 (thiamine) is an essential cofactor for several key enzymes of carbohydrate metabolism. Mammals have to salvage this crucial nutrient from their diet to complement their deficiency of de novo synthesis. In contrast, bacteria, fungi, plants and, as reported here, Plasmodium falciparum, possess a vitamin B1 biosynthesis pathway. The plasmodial pathway identified consists of the three vitamin B1 biosynthetic enzymes 5-(2-hydroxy-ethyl)-4-methylthiazole (THZ) kinase (ThiM), 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP)/HMP-P kinase (ThiD) and thiamine phosphate synthase (ThiE). Recombinant PfThiM and PfThiD proteins were biochemically characterised, revealing K(m)app values of 68 microM for THZ and 12 microM for HMP. Furthermore, the ability of PfThiE for generating vitamin B1 was analysed by a complementation assay with thiE-negative E. coli mutants. All three enzymes are expressed throughout the developmental blood stages, as shown by Northern blotting, which indicates the presence of the vitamin B1 biosynthesis enzymes. However, cultivation of the parasite in minimal medium showed a dependency on the provision of HMP or thiamine. These results demonstrate that the human malaria parasite P. falciparum possesses active vitamin B1 biosynthesis, which depends on external provision of thiamine precursors.
Department of Biochemistry, Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, D-20359 Hamburg, Germany. wrenger@bni-hamburg.de
Carsten
C
Wrenger
Marie-Luise
ML
Eschbach
Ingrid B
IB
Müller
Nathan P
NP
Laun
Tadhg P
TP
Begley
Rolf D
RD
Walter
D019883:Alkyl and Aryl Transferases / Q000096:biosynthesis / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis / Q000235:genetics*; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D011743:Pyrimidines / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction; D013831:Thiamine / Q000096:biosynthesis*
C101901:4-amino-5-hydroxymethyl-2-methylpyrimidine; D011743:Pyrimidines; D019883:Alkyl and Aryl Transferases; C509505:thiamine phosphate synthase, Plasmodium falciparum; C108435:4-methyl-5-(beta-hydroxyethyl)thiazole kinase; D017853:Phosphotransferases (Alcohol Group Acceptor); C108436:4-amino-5-(hydroxymethyl)-2-methylpyrimidine phosphate kinase; D017856:Phosphotransferases (Phosphate Group Acceptor); D013831:Thiamine