Ca2+ signals critical for egress and gametogenesis in malaria parasites depend on a multipass membrane protein that interacts with PKG

• Published in: Science advances Vol. 7; no. 13
• Main Authors: Balestra, Aurélia C, Koussis, Konstantinos, Klages, Natacha, Howell, Steven A, Flynn, Helen R, Bantscheff, Marcus, Pasquarello, Carla, Perrin, Abigail J, Brusini, Lorenzo, Arboit, Patrizia, Sanz, Olalla, Castaño, Laura Peces-Barba, Withers-Martinez, Chrislaine, Hainard, Alexandre, Ghidelli-Disse, Sonja, Snijders, Ambrosius P, Baker, David A, Blackman, Michael J, Brochet, Mathieu
• Format: Journal Article
• Language: English
• Published: American Association for the Advancement of Science 01.03.2021
• Subjects: Cell Biology; Microbiology; SciAdv r-articles
• ISSN: 2375-2548
• DOI: 10.1126/sciadv.abe5396

A membrane protein interacts with PKG and regulates calcium signals at multiple lifecycle stages in malaria parasites. Calcium signaling regulated by the cGMP-dependent protein kinase (PKG) controls key life cycle transitions in the malaria parasite. However, how calcium is mobilized from intracellular stores in the absence of canonical calcium channels in Plasmodium is unknown. Here, we identify a multipass membrane protein, ICM1, with homology to transporters and calcium channels that is tightly associated with PKG in both asexual blood stages and transmission stages. Phosphoproteomic analyses reveal multiple ICM1 phosphorylation events dependent on PKG activity. Stage-specific depletion of Plasmodium berghei ICM1 prevents gametogenesis due to a block in intracellular calcium mobilization, while conditional loss of Plasmodium falciparum ICM1 is detrimental for the parasite resulting in severely reduced calcium mobilization, defective egress, and lack of invasion. Our findings suggest that ICM1 is a key missing link in transducing PKG-dependent signals and provide previously unknown insights into atypical calcium homeostasis in malaria parasites essential for pathology and disease transmission.