title: ARP2/3-Mediated Actin Nucleation Associated With Symbiosome Membrane Is Essential for the Development of Symbiosomes in Infected Cells of Medicago truncatula Root Nodules.
abstract: The nitrogen-fixing rhizobia in the symbiotic infected cells of root nodules are kept in membrane compartments derived from the host cell plasma membrane, forming what are known as symbiosomes. These are maintained as individual units, with mature symbiosomes having a specific radial position in the host cell cytoplasm. The mechanisms that adapt the host cell architecture to accommodate intracellular bacteria are not clear. The intracellular organization of any cell depends heavily on the actin cytoskeleton. Dynamic rearrangement of the actin cytoskeleton is crucial for cytoplasm organization and intracellular trafficking of vesicles and organelles. A key component of the actin cytoskeleton rearrangement is the ARP2/3 complex, which nucleates new actin filaments and forms branched actin networks. To clarify the role of the ARP2/3 complex in the development of infected cells and symbiosomes, we analyzed the pattern of actin microfilaments and the functional role of ARP3 in Medicago truncatula root nodules. In infected cells, ARP3 protein and actin were spatially associated with maturing symbiosomes. Partial ARP3 silencing causes defects in symbiosome development; in particular, ARP3 silencing disrupts the final differentiation steps in functional maturation into nitrogen-fixing units.
authors.affiliation: Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708PB, Wageningen, The Netherlands.
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Gavrin
authors.affiliation: Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708PB, Wageningen, The Netherlands.
authors.forename: Veerle
authors.initials: V
authors.lastname: Jansen
authors.affiliation: Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708PB, Wageningen, The Netherlands.
authors.forename: Sergey
authors.initials: S
authors.lastname: Ivanov
authors.affiliation: Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708PB, Wageningen, The Netherlands.
authors.forename: Ton
authors.initials: T
authors.lastname: Bisseling
authors.affiliation: Laboratory of Molecular Biology, Wageningen University, Droevendaalsesteeg 1, 6708PB, Wageningen, The Netherlands.
authors.forename: Elena
authors.initials: E
authors.lastname: Fedorova
mesh_terms: D051376:Actin-Related Protein 2-3 Complex / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D051378:Actin-Related Protein 3 / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D000199:Actins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure*; D003593:Cytoplasm / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D046913:Medicago truncatula / Q000235:genetics / Q000382:microbiology / Q000648:ultrastructure*; D009586:Nitrogen Fixation; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D018517:Plant Roots / Q000235:genetics / Q000382:microbiology / Q000648:ultrastructure; D021381:Protein Transport; D053204:Root Nodules, Plant / Q000235:genetics / Q000382:microbiology / Q000648:ultrastructure; D016962:Sinorhizobium meliloti / Q000502:physiology*; D013559:Symbiosis
chemical_list: D051376:Actin-Related Protein 2-3 Complex; D051378:Actin-Related Protein 3; D000199:Actins; D010940:Plant Proteins