Premium
The Crystal Structure of Dihydrofolate Reductase‐Thymidylate Synthase from Cryptosporidium hominis Reveals a Novel Architecture for the Bifunctional Enzyme
Author(s) -
O'NEIL ROBERT H.,
LILIEN RYAN H.,
DONAID BRUCE R.,
STROUD ROBERT M.,
ANDERSON AMY C.
Publication year - 2003
Publication title -
journal of eukaryotic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 1066-5234
DOI - 10.1111/j.1550-7408.2003.tb00627.x
Subject(s) - thymidylate synthase , dihydrofolate reductase , library science , biology , enzyme , computer science , biochemistry , genetics , fluorouracil , chemotherapy
Cryptosporidium hominis is an emerging pathogen that primarily affects immune-compromised patients, including those with AIDS. There is no effective cure at this point for the degenerative wasting disease that can follow infection. Dihydrofolate reductase-thymidylate synthase (DHFR-TS) is a bifunctional enzyme in C. hominis and is crucial in the folate cycle for the production of dTMP, one of the four DNA bases. DHFR-TS is an excellent drug target since its inhibition leads to the death of the pathogen. In apicomplexan protozoa, including C. hominis, the gene for DHFR-TS can be partitioned into a DHFR domain, a linker domain and a TS domain. In human cells, DHFR and TS are separate, monofunctional enzymes. We have determined the X-ray crystal structure of DHFR-TS from C. hominis. The structure reveals that the linker polypeptide between the DHFR and TS domains has important structural interactions with the opposite monomer of the homodimeric enzyme. A com- parison of the structure of DHFR-TS from C. hominis and structures of DHFR-TS from Plasmodium falciparum (11) and Leishmania major (5) shows that there are significant structural differences between the apicomplexan and kinetoplastid forms of the enzyme. Additionally, the DHFR and TS domains of the C. hominis enzyme have important sequence and structural differences from the human forms of the enzymes. The species-specific differences are important for future inhibitor design targeting C. hominis.