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Expression and functional characterization of a Plasmodium falciparum Ca2+-ATPase (PfATP4) belonging to a subclass unique to apicomplexan organisms

Expression and functional characterization of a Plasmodium falciparum Ca2+-ATPase (PfATP4) belonging to a subclass unique to apicomplexan organisms
Expression and functional characterization of a Plasmodium falciparum Ca2+-ATPase (PfATP4) belonging to a subclass unique to apicomplexan organisms
We have obtained a full-length P type ATPase sequence (PfATP4) encoded by Plasmodium falciparum and expressed PfATP4 in Xenopus laevis oocytes to study its function. Comparison of the hitherto incomplete open reading frame with other Ca2+-ATPase sequences reveals that PfATP4 differs significantly from previously defined categories. The Ca2+-dependent ATPase activity of PfATP4 is stimulated by a much broader range of [Ca2+]free (3.2-320 µM) than are an avian SERCA1 pump or rabbit SERCA 1a (maximal activity < 10 µM). The activity of PfATP4 is resistant to inhibition by ouabain (200 µM) or thapsigargin (0.8 µM) but is inhibited by vanadate (1 mM) or cyclopiazonic acid (1 µM). We used a quantitative polymerase chain reaction to assay expression of mRNA encoding PfATP4 relative to that for -tubulin in synchronized asexual stages and found variable expression throughout the life cycle with a maximal 5-fold increase in meronts compared with ring stages. This analysis suggests that PfATP4 defines a novel subclass of Ca2+-ATPases unique to apicomplexan organisms and therefore offers potential as a drug target.
0021-9258
10782-10787
Krishna, S.
7aca0235-452e-4755-84f2-27f72598c847
Woodrow, C.
aeb862a4-945c-4b3b-ba5c-8b89c725b7b3
Webb, R.
a2c079b2-109c-4ae9-b3b2-c91bfb0fd43a
Penny, J.
432da6c6-04e8-4db8-a790-0c85f292197a
Takeyasu, K.
8eb6d001-8028-46c3-b1dd-018fa8eede00
Kimura, M.
eec0f994-5e97-4616-b39f-706b56c00fa0
East, J.M.
9fe7f794-1d89-4935-9a99-b831d786056e
Krishna, S.
7aca0235-452e-4755-84f2-27f72598c847
Woodrow, C.
aeb862a4-945c-4b3b-ba5c-8b89c725b7b3
Webb, R.
a2c079b2-109c-4ae9-b3b2-c91bfb0fd43a
Penny, J.
432da6c6-04e8-4db8-a790-0c85f292197a
Takeyasu, K.
8eb6d001-8028-46c3-b1dd-018fa8eede00
Kimura, M.
eec0f994-5e97-4616-b39f-706b56c00fa0
East, J.M.
9fe7f794-1d89-4935-9a99-b831d786056e

Krishna, S., Woodrow, C., Webb, R., Penny, J., Takeyasu, K., Kimura, M. and East, J.M. (2001) Expression and functional characterization of a Plasmodium falciparum Ca2+-ATPase (PfATP4) belonging to a subclass unique to apicomplexan organisms. The Journal of Biological Chemistry, 276 (14), 10782-10787. (doi:10.1074/jbc.M010554200).

Record type: Article

Abstract

We have obtained a full-length P type ATPase sequence (PfATP4) encoded by Plasmodium falciparum and expressed PfATP4 in Xenopus laevis oocytes to study its function. Comparison of the hitherto incomplete open reading frame with other Ca2+-ATPase sequences reveals that PfATP4 differs significantly from previously defined categories. The Ca2+-dependent ATPase activity of PfATP4 is stimulated by a much broader range of [Ca2+]free (3.2-320 µM) than are an avian SERCA1 pump or rabbit SERCA 1a (maximal activity < 10 µM). The activity of PfATP4 is resistant to inhibition by ouabain (200 µM) or thapsigargin (0.8 µM) but is inhibited by vanadate (1 mM) or cyclopiazonic acid (1 µM). We used a quantitative polymerase chain reaction to assay expression of mRNA encoding PfATP4 relative to that for -tubulin in synchronized asexual stages and found variable expression throughout the life cycle with a maximal 5-fold increase in meronts compared with ring stages. This analysis suggests that PfATP4 defines a novel subclass of Ca2+-ATPases unique to apicomplexan organisms and therefore offers potential as a drug target.

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Published date: 1 April 2001

Identifiers

Local EPrints ID: 55999
URI: http://eprints.soton.ac.uk/id/eprint/55999
ISSN: 0021-9258
PURE UUID: 1d3b0721-2c93-4504-8fa7-1d2f32241d8c

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Date deposited: 07 Aug 2008
Last modified: 15 Mar 2024 10:59

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Contributors

Author: S. Krishna
Author: C. Woodrow
Author: R. Webb
Author: J. Penny
Author: K. Takeyasu
Author: M. Kimura
Author: J.M. East

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