Fig. 2

NbBeclin1 interacts with NIb. a Yeast-two hybrid (Y2H) assays for possible interactions between NbBeclin1 and each of the 11 TuMV proteins. NbBeclin1 and 11 viral proteins were fused with a GAL4 activation domain (AD-NbBeclin1) and a GAL4-binding domain (BD-P1, BD-HC-Pro, BD-P3, BD-P3N-PIPO, BD-6K1, BD-CI, BD-6K2, BD-NIa-VPg, BD-NIa-Pro, BD-NIb, BD-CP), respectively. Y2H Gold yeast cells co-transformed with the indicated plasmids were subjected to 10-fold serial dilutions and plated on synthetic dextrose (SD)/-Trp, -Leu, -His, -Ade or SD/-Trp, -Leu medium to screen for positive interactions at 3 days after transformation. Yeast co-transformed with AD-T7-T+BD-T7-53 serves as a positive control; yeast cells co-transformed with AD-NbBeclin1 and the empty BD or with the empty AD and BD-NIb are negative controls. b BiFC assays between NbBeclin1 and NIb in the leaves of H2B-RFP transgenic N. benthamiana. Confocal imaging was performed at 48 hpi. NbBeclin1 and NIb were fused to the N (YN) and C-terminal (YC) fragments of yellow fluorescent protein (YFP). The NbBeclin1-NIb interaction led to the reconstituted fluorescence-competent structure and restoration of yellow fluorescence (green). Nuclei of tobacco leaf epidermal cells are indicated by the expression of H2B-RFP transgene (red). Bars, 50 μm. c Co-localization of NIb-YFP with NbBeclin1-CFP in the leaf cells of H2B-RFP transgenic N. benthamiana by confocal microscopy at 48 hpi. Arrow indicates yellow fluorescence, which was produced from the overlapping of NIb-YFP (green) and NbBeclin1-CFP (red). Bars, 50 μm. d Co-immunoprecipitation (Co-IP) analysis of NbBeclin1-CFP and Myc-NIb in vivo. N. benthamiana leaves were co-infiltrated with A. tumefaciens cells harboring expression vectors to express NbBeclin1-CFP and Myc-NIb (Lane 1), NbBeclin1-CFP and Myc-P3N-PIPO (Lane 2), Myc-NIb and GFP (Lane 3), and GFP and Myc-P3N-PIPO (Lane 4). Leaf protein extracts were incubated with GFP-Trap®_MA magnetic agarose beads (ChromoTek). Samples before (Input) and after (IP) immunopurification were analyzed by immunoblotting using GFP or Myc antibody