Identification and biochemical characterization of vivapains, cysteine proteases of the malaria parasite Plasmodium vivax.
Cysteine proteases play important roles in the life cycles of malaria parasites. Cysteine protease inhibitors block haemoglobin hydrolysis and development in Plasmodium falciparum, suggesting that the cysteine proteases of this major human pathogen, termed falcipains, are appropriate therapeutic targets. To expand our understanding of plasmodial proteases to Plasmodium vivax, the other prevalent human malaria parasite, we identified and cloned genes encoding the P. vivax cysteine proteases, vivapain-2 and vivapain-3, and functionally expressed the proteases in Escherichia coli. The vivapain-2 and vivapain-3 genes predicted papain-family cysteine proteases, which shared a number of unusual features with falcipain-2 and falcipain-3, including large prodomains and short N-terminal extensions on the catalytic domain. Recombinant vivapain-2 and vivapain-3 shared properties with the falcipains, including acidic pH optima, requirements for reducing conditions for activity and hydrolysis of substrates with positively charged residues at P1 and Leu at P2. Both enzymes hydrolysed native haemoglobin at acidic pH and the erythrocyte cytoskeletal protein 4.1 at neutral pH, suggesting similar biological roles to the falcipains. Considering inhibitor profiles, the vivapains were inhibited by fluoromethylketone and vinyl sulphone inhibitors that also inhibited falcipains and have demonstrated potent antimalarial activity.
Na
Byoung-Kuk
BK
Department of Medicine, San Francisco General Hospital, University of California, San Francisco, CA 94143-0811, USA.
Shenai
Bhaskar R
BR
Sijwali
Puran S
PS
Choe
Youngchool
Y
Pandey
Kailash C
KC
Singh
Ajay
A
Craik
Charles S
CS
Rosenthal
Philip J
PJ
D000595:Amino Acid Sequence; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D006868:Hydrolysis; D008565:Membrane Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010966:Plasmodium vivax / Q000201:enzymology*; D011480:Protease Inhibitors / Q000494:pharmacology; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013379:Substrate Specificity
D000962:Antimalarials; D006454:Hemoglobins; D008565:Membrane Proteins; D011480:Protease Inhibitors; D003546:Cysteine Endopeptidases