University of Oulu

Bendes, Á.Á., Kursula, P. & Kursula, I. Structure and function of an atypical homodimeric actin capping protein from the malaria parasite. Cell. Mol. Life Sci. 79, 125 (2022).

Structure and function of an atypical homodimeric actin capping protein from the malaria parasite

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Author: Bendes, Ábris Ádám1; Kursula, Petri1,2; Kursula, Inari1,2
Organizations: 1Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
2Department of Biomedicine, University of Bergen, Bergen, Norway
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 11.6 MB)
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Language: English
Published: Springer Nature, 2022
Publish Date: 2022-08-17


Apicomplexan parasites, such as Plasmodium spp., rely on an unusual actomyosin motor, termed glideosome, for motility and host cell invasion. The actin filaments are maintained by a small set of essential regulators, which provide control over actin dynamics in the different stages of the parasite life cycle. Actin filament capping proteins (CPs) are indispensable heterodimeric regulators of actin dynamics. CPs have been extensively characterized in higher eukaryotes, but their role and functional mechanism in Apicomplexa remain enigmatic. Here, we present the first crystal structure of a homodimeric CP from the malaria parasite and compare the homo- and heterodimeric CP structures in detail. Despite retaining several characteristics of a canonical CP, the homodimeric Plasmodium berghei (Pb)CP exhibits crucial differences to the canonical heterodimers. Both homo- and heterodimeric PbCPs regulate actin dynamics in an atypical manner, facilitating rapid turnover of parasite actin, without affecting its critical concentration. Homo- and heterodimeric PbCPs show partially redundant activities, possibly to rescue actin filament capping in life cycle stages where the β-subunit is downregulated. Our data suggest that the homodimeric PbCP also influences actin kinetics by recruiting lateral actin dimers. This unusual function could arise from the absence of a β-subunit, as the asymmetric PbCP homodimer lacks structural elements essential for canonical barbed end interactions suggesting a novel CP binding mode. These findings will facilitate further studies aimed at elucidating the precise actin filament capping mechanism in Plasmodium.

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Series: Cellular and molecular life sciences
ISSN: 1420-682X
ISSN-E: 1420-9071
ISSN-L: 1420-682X
Volume: 79
Issue: 2
Article number: 125
DOI: 10.1007/s00018-021-04032-0
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: Open access funding provided by University of Bergen (incl Haukeland University Hospital). This work was financially supported by the Academy of Finland, the Sigrid Juselius Foundation, and the Norwegian Research Council. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
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