title: EhCoactosin stabilizes actin filaments in the protist parasite Entamoeba histolytica.
abstract: 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.
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Nitesh
authors.initials: N
authors.lastname: Kumar
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.lastname: Somlata
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Mohit
authors.initials: M
authors.lastname: Mazumder
authors.affiliation: Indian Institute of Science Education and Research, Kolkata, India.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Dutta
authors.affiliation: Indian Institute of Science Education and Research, Kolkata, India.
authors.forename: Sankar
authors.initials: S
authors.lastname: Maiti
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Samudrala
authors.initials: S
authors.lastname: Gourinath
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004748:Entamoeba histolytica / Q000254:growth & development / Q000378:metabolism*; D004749:Entamoebiasis / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D004912:Erythrocytes / Q000737:chemistry* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010587:Phagocytosis; D011487:Protein Conformation; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: C118115:COTL1 protein, human; D008840:Microfilament Proteins; D015800:Protozoan Proteins