Anthrax edema toxin disrupts distinct steps in Rab11-dependent junctional transport

PLoS Pathogens

Janet Z. Liu¹  Ethan Bier¹  Stephen H. Leppla¹  Bernice Aguilar¹  Andrew Hollands²  Mahtab Moayeri³  Victor Nizet³  Beatriz Cruz-Moreno⁴  Stephen Chin⁴  Annabel Guichard⁴  Ruth Schwartz⁴  Lin Zhu⁴  Prashant Jain⁴ 

[1] Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States of America;Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, United States of America;Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States of America;Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America

关键词: Salivary gl;    s;    Drosophila melanogaster;    Toxins;    Cell staining;    Edema;    Cell membranes;    Vesicles;    Guanosine triphosphatase;   

DOI  :  10.1371/journal.ppat.1006603

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Various bacterial toxins circumvent host defenses through overproduction of cAMP. In a previous study, we showed that edema factor (EF), an adenylate cyclase from Bacillus anthracis, disrupts endocytic recycling mediated by the small GTPase Rab11. As a result, cargo proteins such as cadherins fail to reach inter-cellular junctions. In the present study, we provide further mechanistic dissection of Rab11 inhibition by EF using a combination of Drosophila and mammalian systems. EF blocks Rab11 trafficking after the GTP-loading step, preventing a constitutively active form of Rab11 from delivering cargo vesicles to the plasma membrane. Both of the primary cAMP effector pathways -PKA and Epac/Rap1- contribute to inhibition of Rab11-mediated trafficking, but act at distinct steps of the delivery process. PKA acts early, preventing Rab11 from associating with its effectors Rip11 and Sec15. In contrast, Epac functions subsequently via the small GTPase Rap1 to block fusion of recycling endosomes with the plasma membrane, and appears to be the primary effector of EF toxicity in this process. Similarly, experiments conducted in mammalian systems reveal that Epac, but not PKA, mediates the activity of EF both in cell culture and in vivo. The small GTPase Arf6, which initiates endocytic retrieval of cell adhesion components, also contributes to junctional homeostasis by counteracting Rab11-dependent delivery of cargo proteins at sites of cell-cell contact. These studies have potentially significant practical implications, since chemical inhibition of either Arf6 or Epac blocks the effect of EF in cell culture and in vivo, opening new potential therapeutic avenues for treating symptoms caused by cAMP-inducing toxins or related barrier-disrupting pathologies.

【 授权许可】

CC BY