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The Nma1 protein promotes long distance transport mediated by early endosomes in Ustilago maydis
Author(s) -
Schneider Karina,
Farr Theresa,
Pinter Niko,
Schmitt Kerstin,
Valerius Oliver,
Braus Gerhard H.,
Kämper Jörg
Publication year - 2022
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14851
Subject(s) - endosome , biology , ustilago , vesicular transport proteins , endocytic cycle , rab , microbiology and biotechnology , small gtpase , gtpase , internalization , endocytosis , transport protein , vacuole , biochemistry , cytoplasm , receptor , signal transduction , vacuolar protein sorting , intracellular , gene
Early endosomes (EEs) are part of the endocytic transport pathway and resemble the earliest class of transport vesicles between the internalization of extracellular material, their cellular distribution or vacuolar degradation. In filamentous fungi, EEs fulfill important functions in long distance transport of cargoes as mRNAs, ribosomes, and peroxisomes. Formation and maturation of early endosomes is controlled by the specific membrane‐bound Rab‐GTPase Rab5 and tethering complexes as CORVET (class C core vacuole/endosome tethering). In the basidiomycete Ustilago maydis , Rab5a is the prominent GTPase to recruit CORVET to EEs; in rab5a deletion strains, this function is maintained by the second EE‐associated GTPase Rab5b. The tethering‐ and core‐subunits of CORVET are essential, buttressing a central role for EE transport in U. maydis . The function of EEs in long distance transport is supported by the Nma1 protein that interacts with the Vps3 subunit of CORVET. The interaction stabilizes the binding of Vps3 to the CORVET core complex that is recruited to Rab5a via Vps8. Deletion of nma1 leads to a significantly reduced number of EEs, and an increased conversion rate of EEs to late endosomes. Thus, Nma1 modulates the lifespan of EEs to ensure their availability for the various long distance transport processes.