Direct evidence for cyanide-insensitive quinol oxidase (alternative oxidase) in apicomplexan parasite Cryptosporidium parvum: phylogenetic and therapeutic implications.
Cryptosporidium parvum is a parasitic protozoan that causes the diarrheal disease cryptosporidiosis, for which no satisfactory chemotherapy is currently available. Although the presence of mitochondria in this parasite has been suggested, its respiratory system is poorly understood due to difficulties in performing biochemical analyses. In order to better understand the respiratory chain of C. parvum, we surveyed its genomic DNA database in GenBank and identified a partial sequence encoding cyanide-insensitive alternative oxidase (AOX). Based on this sequence, we cloned C. parvum AOX (CpAOX) cDNA from the phylum apicomplexa for the first time. The deduced amino acid sequence (335 a.a.) of CpAOX contains diiron coordination motifs (-E-, -EXXH-) that are conserved among AOXs. Phylogenetic analysis suggested that CpAOX is a mitochondrial-type AOX, possibly derived from mitochondrial endosymbiont gene transfer. The recombinant enzyme expressed in Escherichia coli showed quinol oxidase activity. This activity was insensitive to cyanide and highly sensitive to ascofuranone, a specific inhibitor of trypanosome AOX.
Suzuki
Takashi
T
Department of Molecular Parasitology, Nagoya City University, Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
Hashimoto
Tetsuo
T
Yabu
Yoshisada
Y
Kido
Yasutoshi
Y
Sakamoto
Kimitoshi
K
Nihei
Coh-ichi
C
Hato
Mariko
M
Suzuki
Shu-ichi
S
Amano
Yuko
Y
Nagai
Kazuo
K
Hosokawa
Tomoyoshi
T
Minagawa
Nobuko
N
Ohta
Nobuo
N
Kita
Kiyoshi
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003457:Cryptosporidiosis / Q000188:drug therapy; D016785:Cryptosporidium parvum / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012717:Sesquiterpenes / Q000494:pharmacology
D016054:DNA, Protozoan; D004791:Enzyme Inhibitors; D011994:Recombinant Proteins; D012717:Sesquiterpenes; D010088:Oxidoreductases; C020094:duroquinol oxidase; C006640:ascofuranone