scholarly journals SKP1-like protein, CrSKP1-e, interacts with pollen-specific F-box proteins and assembles into SCF-type E3 complex in ‘Wuzishatangju’ (Citrus reticulata Blanco) pollen

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10578
Author(s):  
Yi Ren ◽  
Qingzhu Hua ◽  
Jiayan Pan ◽  
Zhike Zhang ◽  
Jietang Zhao ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Citrus Reticulata ◽  
S Locus ◽  
Binding Assays ◽  
In Vitro Binding ◽  
Genome Wide ◽  
Ubiquitin Ligase Complex ◽  
Vitro Binding

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’.

scholarly journals Virion-Associated Vpr Alleviates a Postintegration Block to HIV-1 Infection of Dendritic Cells

2017 ◽  
Vol 91 (13) ◽  
Author(s):  
Caitlin M. Miller ◽  
Hisashi Akiyama ◽  
Luis M. Agosto ◽  
Ann Emery ◽  
Chelsea R. Ettinger ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Culture ◽  
Dendritic Cells ◽  
Ubiquitin Ligase ◽  
Culture System ◽  
E3 Ubiquitin Ligase ◽  
Cell Culture System ◽  
Ubiquitin Ligase Complex ◽  
Hiv 1

ABSTRACT Viral protein R (Vpr) is an HIV-1 accessory protein whose function remains poorly understood. In this report, we sought to determine the requirement of Vpr for facilitating HIV-1 infection of monocyte-derived dendritic cells (MDDCs), one of the first cell types to encounter virus in the peripheral mucosal tissues. In this report, we characterize a significant restriction of Vpr-deficient virus replication and spread in MDDCs alone and in cell-to-cell spread in MDDC-CD4+ T cell cocultures. This restriction of HIV-1 replication in MDDCs was observed in a single round of virus replication and was rescued by the expression of Vpr in trans in the incoming virion. Interestingly, infections of MDDCs with viruses that encode Vpr mutants unable to interact with either the DCAF1/DDB1 E3 ubiquitin ligase complex or a host factor hypothesized to be targeted for degradation by Vpr also displayed a significant replication defect. While the extent of proviral integration in HIV-1-infected MDDCs was unaffected by the absence of Vpr, the transcriptional activity of the viral long terminal repeat (LTR) from Vpr-deficient proviruses was significantly reduced. Together, these results characterize a novel postintegration restriction of HIV-1 replication in MDDCs and show that the interaction of Vpr with the DCAF1/DDB1 E3 ubiquitin ligase complex and the yet-to-be-identified host factor might alleviate this restriction by inducing transcription from the viral LTR. Taken together, these findings identify a robust in vitro cell culture system that is amenable to addressing mechanisms underlying Vpr-mediated enhancement of HIV-1 replication. IMPORTANCE Despite decades of work, the function of the HIV-1 protein Vpr remains poorly understood, primarily due to the lack of an in vitro cell culture system that demonstrates a deficit in replication upon infection with viruses in the absence of Vpr. In this report, we describe a novel cell infection system that utilizes primary human dendritic cells, which display a robust decrease in viral replication upon infection with Vpr-deficient HIV-1. We show that this replication difference occurs in a single round of infection and is due to decreased transcriptional output from the integrated viral genome. Viral transcription could be rescued by virion-associated Vpr. Using mutational analysis, we show that domains of Vpr involved in binding to the DCAF1/DDB1/E3 ubiquitin ligase complex and prevention of cell cycle progression into mitosis are required for LTR-mediated viral expression, suggesting that the evolutionarily conserved G2 cell cycle arrest function of Vpr is essential for HIV-1 replication.

scholarly journals DNA Modeling Reveals an Extended Lac Repressor Conformation in Classic In Vitro Binding Assays

2011 ◽  
Vol 101 (3) ◽  
pp. 718-726 ◽  
Author(s):  
Andrew D. Hirsh ◽  
Todd D. Lillian ◽  
Troy A. Lionberger ◽  
N.C. Perkins
Keyword(s):  
Lac Repressor ◽  
Binding Assays ◽  
In Vitro Binding ◽  
Vitro Binding ◽  
Dna Modeling

scholarly journals BLADE-ON-PETIOLE proteins act in an E3 ubiquitin ligase complex to regulate PHYTOCHROME INTERACTING FACTOR 4 abundance

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Bo Zhang ◽  
Mattias Holmlund ◽  
Severine Lorrain ◽  
Mikael Norberg ◽  
László Bakó ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Flower Development ◽  
Red Light ◽  
E3 Ubiquitin Ligase ◽  
Plant Responses ◽  
Signaling Mechanism ◽  
Ubiquitin Ligase Complex ◽  
Molecular Determinants ◽  
Subsequent Degradation

Both light and temperature have dramatic effects on plant development. Phytochrome photoreceptors regulate plant responses to the environment in large part by controlling the abundance of PHYTOCHROME INTERACTING FACTOR (PIF) transcription factors. However, the molecular determinants of this essential signaling mechanism still remain largely unknown. Here, we present evidence that the BLADE-ON-PETIOLE (BOP) genes, which have previously been shown to control leaf and flower development in Arabidopsis, are involved in controlling the abundance of PIF4. Genetic analysis shows that BOP2 promotes photo-morphogenesis and modulates thermomorphogenesis by suppressing PIF4 activity, through a reduction in PIF4 protein level. In red-light-grown seedlings PIF4 ubiquitination was reduced in the bop2 mutant. Moreover, we found that BOP proteins physically interact with both PIF4 and CULLIN3A and that a CULLIN3-BOP2 complex ubiquitinates PIF4 in vitro. This shows that BOP proteins act as substrate adaptors in a CUL3BOP1/BOP2 E3 ubiquitin ligase complex, targeting PIF4 proteins for ubiquitination and subsequent degradation.

scholarly journals Direct phosphorylation of HY5 by SPA1 kinase to regulate photomorphogenesis in Arabidopsis

2020 ◽  
Author(s):  
Wenli Wang ◽  
Inyup Paik ◽  
Junghyun Kim ◽  
Xilin Hou ◽  
Sibum Sung ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Active Form ◽  
E3 Ubiquitin Ligase ◽  
Kinase Domain ◽  
Ubiquitin Ligase Complex ◽  
The Stability ◽  
Target Promoters ◽  
Spa Proteins

SUMMARYELONGATED HYPOCOTYL5 (HY5) is a key transcription factor which promotes photomorphogenesis by regulating complex downstream growth programs. Previous studies suggest that the regulation of HY5 mainly depends on the CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) - SUPPRESSOR OF PHYTOCHROME A-105 (SPA) E3 ubiquitin ligase complex, which degrades positively acting transcription factors of light signaling to repress photomorphogenesis in the dark. SPA proteins function not only as a component of the E3 ubiquitin ligase complex but also as a kinase of PHYTOCHROME INTERACTING FACTOR1 (PIF1) through its N-terminal kinase domain. Here, we show that HY5 is a new substrate of SPA1 kinase. SPA1 can directly phosphorylate HY5 in vitro and in vivo. We also demonstrate that unphosphorylated HY5 strongly interacts with both COP1 and SPA1 than phosphorylated HY5, is the preferred substrate for degradation, whereas phosphorylated HY5 is more stable in the dark. In addition, unphosphorylated HY5 actively binds to the target promoters, and is physiologically more active form. Consistently, the transgenic plants expressing unphosphorylated mutant of HY5 displays enhanced photomorphogenesis. Collectively, our study revealed that SPA1 fine-tunes the stability and the activity of HY5 to regulate photomorphogenesis.

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