EhCoactosin stabilizes actin filaments in the protist parasite Entamoeba histolytica.

• Main Authors: Nitesh Kumar, Somlata, Mohit Mazumder, Priyanka Dutta, Sankar Maiti, Samudrala Gourinath
• Format: Article
• Language: English
• Published: Public Library of Science (PLoS) 2014-09-01
• Series: PLoS Pathogens
• Online Access: http://europepmc.org/articles/PMC4161475?pdf=render

Entamoeba histolytica is a protist parasite that is the causative agent of amoebiasis, and is a highly motile organism. The motility is essential for its survival and pathogenesis, and a dynamic actin cytoskeleton is required for this process. EhCoactosin, an actin-binding protein of the ADF/cofilin family, participates in actin dynamics, and here we report our studies of this protein using both structural and functional approaches. The X-ray crystal structure of EhCoactosin resembles that of human coactosin-like protein, with major differences in the distribution of surface charges and the orientation of terminal regions. According to in vitro binding assays, full-length EhCoactosin binds both F- and G-actin. Instead of acting to depolymerize or severe F-actin, EhCoactosin directly stabilizes the polymer. When EhCoactosin was visualized in E. histolytica cells using either confocal imaging or total internal reflectance microscopy, it was found to colocalize with F-actin at phagocytic cups. Over-expression of this protein stabilized F-actin and inhibited the phagocytic process. EhCoactosin appears to be an unusual type of coactosin involved in E. histolytica actin dynamics.