El Kasmi F, Krause C, Hiller U, Stierhof YD, Mayer U, Conner L, Kong L, Reichardt I, Sanderfoot AA, Juergens G

Membrane fusion is mediated by SNARE complexes. Although membrane fusion is required for separating daughter cells in eukaryotic cytokinesis, SNARE complexes involved are not known. In plants, membrane vesicles targeted to the cell division plane fuse with one another to form the partitioning membrane, progressing from the center to the ...

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periphery of the cell. In Arabidopsis, the cytokinesis-specific Qa-SNARE KNOLLE interacts with two other Q-SNAREs, SNAP33 and NPSN11, whose role in cytokinesis is not clear. Here we show by coimmunoprecipitation that KNOLLE forms two SNARE complexes that differ in composition. One complex is modeled on the trimeric plasma-membrane type of SNARE complex, comprising promiscuous Qb,c-SNARE SNAP33 and R-SNARE VAMP721,722 also involved in innate immunity. In contrast, the other KNOLLE-containing complex is tetrameric and comprises Qb-SNARE NPSN11, Qc-SNARE SYP71 and also VAMP721,722. Elimination of only one or the other type of KNOLLE complex by mutation including the double mutant npsn11 syp71 causes a mild or no cytokinesis defect. In contrast, the two double mutants snap33 npsn11 and snap33 syp71 eliminate both types of KNOLLE complexes and display knolle-like cytokinesis defects. Thus, the two distinct types of KNOLLE complexes appear to jointly mediate membrane fusion in Arabidopsis cytokinesis.

Date: Mar. 20, 2013

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