title: Identification and characterization of an Arabidopsis mutant with altered localization of NIP5;1, a plasma membrane boric acid channel, reveals the requirement for D-galactose in endomembrane organization.
abstract: Endomembrane organization is important for various aspects of cell physiology, including membrane protein trafficking. To explore the molecular mechanisms regulating the trafficking of plasma membrane-localized proteins in plants, we screened for Arabidopsis mutants with defective localization of green fluorescent protein (GFP)-nodulin 26-like intrinsic protein (NIP)5;1. Fluorescence imaging-based screening led to the isolation of a mutant which accumulated abnormal intracellular aggregates labeled by GFP-NIP5;1. The aggregates appeared in epidermal cells in the root elongation zone and included the trans-Golgi network/early endosomes. Rough mapping and whole-genome sequencing identified the mutant as an allele of UDP-glucose 4-epimerase 4 (uge4)/root hair defective 1 (rhd1) /root epidermal bulgar 1 (reb 1), which was originally defined as a cell wall mutant. The responsible gene encodes UDP-glucose 4-epimerase 4 (UGE4), which functions in the biosynthesis of d-galactose, especially for the synthesis of the cell wall polysaccharide xyloglucan and arabinogalactan proteins (AGPs). The endomembrane aggregates in the mutants were absent in the presence of d-galactose, indicative of a requirement for a d-galactose-containing component in endomembrane organization. Genetic and pharmacological analyses suggested that the aggregates were not caused by the disruption of cell wall polysaccharides or the cytoskeleton. Overall, our results suggest that UGE4 activity in d-galactose synthesis is required for the structure of cell wall polysaccharides and endomembrane organization.
authors.affiliation: Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589 Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Uehara
authors.forename: Sheliang
authors.initials: S
authors.lastname: Wang
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kamiya
authors.forename: Shuji
authors.initials: S
authors.lastname: Shigenobu
authors.forename: Katsushi
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Toru
authors.initials: T
authors.lastname: Fujiwara
authors.forename: Satoshi
authors.initials: S
authors.lastname: Naito
authors.forename: Junpei
authors.initials: J
authors.lastname: Takano
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000483:Alleles; D020346:Aquaporins / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001888:Boric Acids / Q000378:metabolism; D002449:Cell Aggregation / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D002874:Chromosome Mapping; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D005690:Galactose / Q000494:pharmacology*; D018745:Genome, Plant; D005936:Glucans / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism; D009088:Mucoproteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D010940:Plant Proteins / Q000378:metabolism; D011134:Polysaccharides / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D017422:Sequence Analysis, DNA; D014534:UDPglucose 4-Epimerase / Q000378:metabolism*; D014990:Xylans / Q000378:metabolism; D021601:trans-Golgi Network / Q000187:drug effects / Q000378:metabolism
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D001888:Boric Acids; D005030:Ethylenes; D005936:Glucans; D007473:Ion Channels; D009088:Mucoproteins; C512214:NIP5;1 protein, Arabidopsis; D010940:Plant Proteins; D011134:Polysaccharides; D014990:Xylans; C006619:arabinogalactan proteins; D049452:Green Fluorescent Proteins; C029353:xyloglucan; C036216:ethylene; C495671:RHD1 protein, Arabidopsis; D014534:UDPglucose 4-Epimerase; C032688:boric acid; D005690:Galactose
keywords: Arabidopsis thaliana; Cell wall, endomembrane, d-galactose, UDP-d-glucose-4-epimerase