title: Gem1 and ERMES do not directly affect phosphatidylserine transport from ER to mitochondria or mitochondrial inheritance.
abstract: In yeast, a protein complex termed the ER-Mitochondria Encounter Structure (ERMES) tethers mitochondria to the endoplasmic reticulum. ERMES proteins are implicated in a variety of cellular functions including phospholipid synthesis, mitochondrial protein import, mitochondrial attachment to actin, polarized mitochondrial movement into daughter cells during division, and maintenance of mitochondrial DNA (mtDNA). The mitochondrial-anchored Gem1 GTPase has been proposed to regulate ERMES functions. Here, we show that ERMES and Gem1 have no direct role in the transport of phosphatidylserine (PS) from the ER to mitochondria during the synthesis of phosphatidylethanolamine (PE), as PS to PE conversion is not affected in ERMES or gem1 mutants. In addition, we report that mitochondrial inheritance defects in ERMES mutants are a secondary consequence of mitochondrial morphology defects, arguing against a primary role for ERMES in mitochondrial association with actin and mitochondrial movement. Finally, we show that ERMES complexes are long-lived, and do not depend on the presence of Gem1. Our findings suggest that the ERMES complex may have primarily a structural role in maintaining mitochondrial morphology.
authors.affiliation: Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
authors.forename: Tammy T
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Lewandowska
authors.forename: Jae-Yeon
authors.initials: JY
authors.lastname: Choi
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Markgraf
authors.forename: Mirco
authors.initials: M
authors.lastname: Junker
authors.forename: Mesut
authors.initials: M
authors.lastname: Bilgin
authors.forename: Christer S
authors.initials: CS
authors.lastname: Ejsing
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Voelker
authors.forename: Tom A
authors.initials: TA
authors.lastname: Rapoport
authors.forename: Janet M
authors.initials: JM
authors.lastname: Shaw
mesh_terms: D001692:Biological Transport; D004272:DNA, Mitochondrial / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D008928:Mitochondria / Q000378:metabolism*; D024101:Mitochondrial Proteins / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010718:Phosphatidylserines / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism
chemical_list: D004272:DNA, Mitochondrial; C120472:GEM1 protein, S cerevisiae; D024101:Mitochondrial Proteins; C571177:Mmr1 protein, S cerevisiae; D010714:Phosphatidylethanolamines; D010718:Phosphatidylserines; D029701:Saccharomyces cerevisiae Proteins; C468556:Ypt11 protein, S cerevisiae; D049452:Green Fluorescent Proteins; C483858:phosphatidylethanolamine; D020558:GTP Phosphohydrolases; D020691:rab GTP-Binding Proteins