The Trypanosome Exocyst: A Conserved Structure Revealing a New Role in Endocytosis

Autor: Boehm, Cordula M., Obado, Samson, Gadelha, Catarina, Kaupisch, Alexandra, Manna, Paul T., Gould, Gwyn W., Munson, Mary, Chait, Brian T., Rout, Michael P., Field, Mark C.
Jazyk: angličtina
Rok vydání: 2017
Předmět:
Proteomics
Trypanosoma
QH301-705.5
Blotting
Western
Trypanosoma brucei brucei
Cultured tumor cells
Protozoan Proteins
Biochemistry
Polymerase Chain Reaction
RNA interference
Microscopy
Electron
Transmission
Genetics
Humans
Small interfering RNAs
HeLa cells
Vesicles
Biology (General)
Non-coding RNA
Protozoans
Secretory Pathway
Biology and life sciences
Cell Membrane
Organisms
Cell Biology
RC581-607
Cell cultures
Biological Evolution
Endocytosis
Parasitic Protozoans
QR
Gene regulation
Nucleic acids
Research and analysis methods
Protein Transport
Kinetoplasts
Genetic interference
Microscopy
Fluorescence
Cell Processes
RNA
Cell lines
Epigenetics
Gene expression
Cellular Structures and Organelles
Immunologic diseases. Allergy
Lysosomes
Biological cultures
Research Article
Trypanosoma Brucei Gambiense
Zdroj: PLoS Pathogens, Vol 13, Iss 1, p e1006063 (2017)
PLoS Pathogens
ISSN: 1553-7374
1553-7366
Popis: Membrane transport is an essential component of pathogenesis for most infectious organisms. In African trypanosomes, transport to and from the plasma membrane is closely coupled to immune evasion and antigenic variation. In mammals and fungi an octameric exocyst complex mediates late steps in exocytosis, but comparative genomics suggested that trypanosomes retain only six canonical subunits, implying mechanistic divergence. We directly determined the composition of the Trypanosoma brucei exocyst by affinity isolation and demonstrate that the parasite complex is nonameric, retaining all eight canonical subunits (albeit highly divergent at the sequence level) plus a novel essential subunit, Exo99. Exo99 and Sec15 knockdowns have remarkably similar phenotypes in terms of viability and impact on morphology and trafficking pathways. Significantly, both Sec15 and Exo99 have a clear function in endocytosis, and global proteomic analysis indicates an important role in maintaining the surface proteome. Taken together these data indicate additional exocyst functions in trypanosomes, which likely include endocytosis, recycling and control of surface composition. Knockdowns in HeLa cells suggest that the role in endocytosis is shared with metazoan cells. We conclude that, whilst the trypanosome exocyst has novel components, overall functionality appears conserved, and suggest that the unique subunit may provide therapeutic opportunities.
Author Summary Trafficking is an important process in most eukaryotic cells, and has been adapted for specific species to accommodate their requirements. There is good evidence for the innovation of novel routes and mechanisms in plants and animals in terms of the evolution of lineage-specific proteins that function within the endocytic and exocytic pathways, and emerging data indicates that similar novel features are also present in unicellular protozoa. This suggests the likely presence of significant variation within membrane trafficking. Here we have identified a novel component of the exocyst, a complex that is important in late stages of protein secretion. Moreover, we also find evidence that the exocyst is involved in endocytosis extending the functional reach of this complex.
Databáze: OpenAIRE
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