Evidence for a “Wattle and Daub” Model of the Cyst Wall of Entamoeba

PLoS Pathogens

Landon Moore¹  Esther Bullitt¹  Ken Jang²  Phillips W. Robbins³  Anirban Chatterjee⁴  Sudip K. Ghosh⁴  John Samuelson⁴ 

[1] Department of Biophysics and Physiology, Boston University School of Medicine, Boston, Massachusetts, United States of America;Department of Biotechnology, Indian Institute of Technology, Kharagpur, West Bengal, India;Department of Genetics and Genomics, Boston University School of Medicine, Boston, Massachusetts, United States of America;Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, United States of America

关键词: Lectins;    Chitin;    Vesicles;    Negative staining;    Trophozoites;    Fluorescence microscopy;    Bacterial genetics;    DAPI staining;   

DOI  :  10.1371/journal.ppat.1000498

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The cyst wall of Entamoeba invadens (Ei), a model for the human pathogen Entamoeba histolytica, is composed of fibrils of chitin and three chitin-binding lectins called Jacob, Jessie3, and chitinase. Here we show chitin, which was detected with wheat germ agglutinin, is made in secretory vesicles prior to its deposition on the surface of encysting Ei. Jacob lectins, which have tandemly arrayed chitin-binding domains (CBDs), and chitinase, which has an N-terminal CBD, were each made early during encystation. These results are consistent with their hypothesized roles in cross-linking chitin fibrils (Jacob lectins) and remodeling the cyst wall (chitinase). Jessie3 lectins likely form the mortar or daub of the cyst wall, because 1) Jessie lectins were made late during encystation; 2) the addition to Jessie lectins to the cyst wall correlated with a marked decrease in the permeability of cysts to nucleic acid stains (DAPI) and actin-binding heptapeptide (phalloidin); and 3) recombinant Jessie lectins, expressed as a maltose-binding proteins in the periplasm of Escherichia coli, caused transformed bacteria to agglutinate in suspension and form a hard pellet that did not dissociate after centrifugation. Jessie3 appeared as linear forms and rosettes by negative staining of secreted recombinant proteins. These findings provide evidence for a “wattle and daub” model of the Entamoeba cyst wall, where the wattle or sticks (chitin fibrils likely cross-linked by Jacob lectins) is constructed prior to the addition of the mortar or daub (Jessie3 lectins).

【 授权许可】

CC BY