title: A nodule-specific protein secretory pathway required for nitrogen-fixing symbiosis.
abstract: The nitrogen-fixing symbiosis between Sinorhizobium meliloti and its leguminous host plant Medicago truncatula occurs in a specialized root organ called the nodule. Bacteria that are released into plant cells are surrounded by a unique plant membrane compartment termed a symbiosome. We found that in the symbiosis-defective dnf1 mutant of M. truncatula, bacteroid and symbiosome development are blocked. We identified the DNF1 gene as encoding a subunit of a signal peptidase complex that is highly expressed in nodules. By analyzing data from whole-genome expression analysis, we propose that correct symbiosome development in M. truncatula requires the orderly secretion of protein constituents through coordinated up-regulation of a nodule-specific pathway exemplified by DNF1.
authors.affiliation: Department of Biology, Stanford University, Stanford, CA 94305, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Joel
authors.initials: J
authors.lastname: Griffitts
authors.forename: Colby
authors.initials: C
authors.lastname: Starker
authors.forename: Elena
authors.initials: E
authors.lastname: Fedorova
authors.forename: Erik
authors.initials: E
authors.lastname: Limpens
authors.forename: Sergey
authors.initials: S
authors.lastname: Ivanov
authors.forename: Ton
authors.initials: T
authors.lastname: Bisseling
authors.forename: Sharon
authors.initials: S
authors.lastname: Long
mesh_terms: D004721:Endoplasmic Reticulum / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D017343:Genes, Plant; D046913:Medicago truncatula / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009586:Nitrogen Fixation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D053204:Root Nodules, Plant / Q000378:metabolism / Q000382:microbiology*; D055571:Secretory Pathway; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013559:Symbiosis
chemical_list: D008565:Membrane Proteins; D010940:Plant Proteins; D021122:Protein Subunits; D012697:Serine Endopeptidases; C026515:type I signal peptidase