Purification and initial characterization of Plasmodium falciparum K + channels, PfKch1 and PfKch2 produced in Saccharomyces cerevisiae

Resistance towards known antimalarial drugs poses a significant problem, urging for novel drugs that target vital proteins in the malaria parasite Plasmodium falciparum . However, recombinant production of malaria proteins is notoriously difficult. To address this, we have investigated two putative K + channels, PfKch1 and PfKch2, identified in the P. falciparum genome. We show that PfKch1 and PfKch2 and a C-terminally truncated version of PfKch1 (PfKch1 1−1094 ) could indeed be functionally expressed in vivo, since a K + -uptake deficient Saccharomyces cerevisiae strain was complemented by the P. falciparum cDNAs. PfKch1 1−1094 -GFP and GFP-PfKch2 fusion proteins were overexpressed in yeast, purified and reconstituted in lipid bilayers to determine their electrophysiological activity. Single channel conductance amounted to 16 ± 1 pS for PfKch1 1−1094 -GFP and 28 ± 2 pS for GFP-PfKch2. We predicted regulator of K + -conductance (RCK) domains in the C-terminals of both channels, and we accordingly measured channel activity in the presence of Ca 2+.