Characterization of Aspergillus nidulans DidB Did2, a non-essential component of the multivesicular body pathway.
ESCRT-III heteropolymers mediate membrane protein cargo sorting into multivesicular endosomes for subsequent vacuolar degradation. We studied the localization of largely uncharacterized Aspergillus nidulans ESCRT-III using its key structural component Vps32 and the 'associated' component DidB(Did2). Vps32-GFP localizes to motile early endosomes as reported, but predominates in aggregates often associated with vacuoles due to inability to dissociate from endosomes. DidB(Did)(2) regulating Vps4 (the ATPase disassembling ESCRT-III) is not essential. Consistent with this accessory role, didB Delta is unable to block the MVB sorting of the glutamate transporter AgtA, but increases its steady-state level and mislocalizes a fraction of the permease to the plasma membrane under conditions promoting its vacuolar targeting. didB Delta exacerbates the dominant-negative growth defect resulting from Vps32-GFP over-expression. A proportion of DidB-GFP is detectable in early endosomes colocalizing with RabA(Rab5) and accumulating in nudA1 tips, suggesting that ESCRT-III assembles on endosomes from the early steps of the endocytic pathway.
Hervás-Aguilar
América
A
Department of Molecular and Cellular Medicine, Centro de Investigaciones Biológicas CSIC, Ramiro de Maeztu 9, Madrid 28040, Spain.
Rodríguez-Galán
Olga
O
Galindo
Antonio
A
Abenza
Juan F
JF
Arst
Herbert N
HN
Peñalva
Miguel A
MA
D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism; D001233:Aspergillus nidulans / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D011992:Endosomes / Q000737:chemistry / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D057146:Multivesicular Bodies / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D022161:Transport Vesicles / Q000378:metabolism
D056827:Endosomal Sorting Complexes Required for Transport; D005656:Fungal Proteins; D008565:Membrane Proteins; D049452:Green Fluorescent Proteins; D000251:Adenosine Triphosphatases