Open AccessSKP1-like protein, CrSKP1-e, interacts with pollen-specific F-box proteins and assembles into SCF-type E3 complex in ‘Wuzishatangju’ (Citrus reticulata Blanco) pollen
Author(s) -
Yi Ren,
Qian Hua,
Jiayan Pan,
Zhike Zhang,
Jiamin Zhao,
Xinhua He,
Yonghua Qin,
Guibing Hu
Publication year - 2020
Publication title -
peerj
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.927
H-Index - 70
ISSN - 2167-8359
DOI - 10.7717/peerj.10578
Subject(s) - skp1 , biology , f box protein , gene , ubiquitin ligase , ribonuclease , rnase p , bimolecular fluorescence complementation , microbiology and biotechnology , clementine (nuclear reactor) , genetics , pollen , ubiquitin , botany , chemistry , rna , nuclear chemistry
S-ribonuclease (S-RNase)-based self-incompatibility (SI) mechanisms have been extensively studied in Solanaceae, Rosaceae and Plantaginaceae. S-RNase-based SI is controlled by two closely related genes, S-RNase and S-locus F-box ( SLF ), located at a polymorphic S-locus. In the SI system, the SCF-type (SKP1-CUL1-F-box-RBX1) complex functions as an E3 ubiquitin ligase complex for ubiquitination of non-self S-RNase. Pummelo ( Citrus grandis ) and several mandarin cultivars are suggested to utilize an S-RNase-based SI system. However, the molecular mechanism of the non-S-factors involved in the SI reaction is not straightforward in Citrus . To investigate the SCF-type E3 complex responsible for the SI reaction in mandarin, SLF, SKP1-like and CUL1 candidates potentially involved in the SI reaction of ‘Wuzishatangju’ ( Citrus reticulata Blanco) were identified based on the genome-wide identification and expression analyses. Sixteen pollen-specific F-box genes ( CrFBX1-CrFBX16 ), one pollen-specific SKP1-like gene ( CrSKP1-e ) and two CUL1 genes ( CrCUL1A and CrCUL1B ) were identified and cloned from ‘Wuzishatangju’. Yeast two-hybrid (Y2H) and in vitro binding assays showed that five CrFBX proteins could bind to CrSKP1-e, which is an ortholog of SSK1 (SLF-interacting-SKP1-like), a non-S-factor responsible for the SI reaction. Luciferase complementation imaging (LCI) and in vitro binding assays also showed that CrSKP1-e interacts with the N-terminal region of both CrCUL1A and CrCUL1B. These results indicate that CrSKP1-e may serve as a functional member of the SCF-type E3 ubiquitin ligase complex in ‘Wuzishatangju’.