In the human malaria parasite Plasmodium falciparum, polyamines are synthesized by a bifunctional ornithine decarboxylase, S-adenosylmethionine decarboxylase.
The polyamines putrescine, spermidine, and spermine are crucial for cell differentiation and proliferation. Interference with polyamine biosynthesis by inhibition of the rate-limiting enzymes ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC) has been discussed as a potential chemotherapy of cancer and parasitic infections. Usually both enzymes are individually transcribed and highly regulated as monofunctional proteins. We have isolated a cDNA from the malaria parasite Plasmodium falciparum that encodes both proteins on a single open reading frame, with the AdoMetDC domain in the N-terminal region connected to a C-terminal ODC domain by a hinge region. The predicted molecular mass of the entire transcript is 166 kDa. The ODC/AdoMetDC coding region was subcloned into the expression vector pASK IBA3 and transformed into the AdoMetDC- and ODC-deficient Escherichia coli cell line EWH331. The resulting recombinant protein exhibited both AdoMetDC and ODC activity and co-eluted after gel filtration on Superdex S-200 at approximately 333 kDa, which is in good agreement with the molecular mass of approximately 326 kDa determined for the native protein from isolated P. falciparum. SDS-polyacrylamide gel electrophoresis analysis of the recombinant ODC/AdoMetDC revealed a heterotetrameric structure of the active enzyme indicating processing of the AdoMetDC domain. The data presented describe the occurrence of a unique bifunctional ODC/AdoMetDC in P. falciparum, an organization which is possibly exploitable for the design of new antimalarial drugs.
Müller
S
S
Bernhard Nocht Institute for Tropical Medicine, Biochemical Parasitology, Bernhard-Nocht-Str. 74, D-20359 Hamburg, Germany.
Da'dara
A
A
Lüersen
K
K
Wrenger
C
C
Das Gupta
R
R
Madhubala
R
R
Walter
R D
RD
D012437:Adenosylmethionine Decarboxylase / Q000235:genetics / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D000818:Animals; D004912:Erythrocytes / Q000469:parasitology; D015870:Gene Expression; D015723:Gene Library; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification* / Q000494:pharmacology; D016366:Open Reading Frames; D009955:Ornithine Decarboxylase / Q000235:genetics / Q000302:isolation & purification*; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D011073:Polyamines / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000302:isolation & purification; D016053:RNA, Protozoan / Q000235:genetics / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D009097:Multienzyme Complexes; D011073:Polyamines; D012333:RNA, Messenger; D016053:RNA, Protozoan; D011994:Recombinant Proteins; D009955:Ornithine Decarboxylase; D012437:Adenosylmethionine Decarboxylase