Crystal structure of S-adenosyl-L-homocysteine hydrolase from the human malaria parasite Plasmodium falciparum.
The human malaria parasite Plasmodium falciparum is responsible for the death of more than a million people each year. The emergence of strains of malarial parasite resistant to conventional drug therapy has stimulated searches for antimalarials with novel modes of action. S-Adenosyl-L-homocysteine hydrolase (SAHH) is a regulator of biological methylations. Inhibitors of SAHH affect the methylation status of nucleic acids, proteins, and small molecules. P.falciparum SAHH (PfSAHH) inhibitors are expected to provide a new type of chemotherapeutic agent against malaria. Despite the pressing need to develop selective PfSAHH inhibitors as therapeutic drugs, only the mammalian SAHH structures are currently available. Here, we report the crystal structure of PfSAHH complexed with the reaction product adenosine (Ado). Knowledge of the structure of the Ado complex in combination with a structural comparison with Homo sapiens SAHH (HsSAHH) revealed that a single substitution between the PfSAHH (Cys59) and HsSAHH (Thr60) accounts for the differential interactions with nucleoside inhibitors. To examine roles of the Cys59 in the interactions with nucleoside inhibitors, a mutant PfSAHH was prepared. A replacement of Cys59 by Thr results in mutant PfSAHH, which shows HsSAHH-like nucleoside inhibitor sensitivity. The present structure should provide opportunities to design potent and selective PfSAHH inhibitors.
Tanaka
Nobutada
N
School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan. ntanaka@pharm.showa-u.ac.jp <ntanaka@pharm.showa-u.ac.jp>
Nakanishi
Masayuki
M
Kusakabe
Yoshio
Y
Shiraiwa
Katsura
K
Yabe
Saori
S
Ito
Yasutomo
Y
Kitade
Yukio
Y
Nakamura
Kazuo T
KT
D043383:Adenosylhomocysteinase / Q000037:antagonists & inhibitors / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy / Q000469:parasitology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010963:Plasmodium falciparum / Q000201:enzymology*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
D004791:Enzyme Inhibitors; D043383:Adenosylhomocysteinase