scholarly journals Overlapping Functions of the Paralogous Proteins AtPAP2 and AtPAP9 in Arabidopsis thaliana

2021 ◽  
Vol 22 (14) ◽  
pp. 7243
Author(s):  
Renshan Zhang ◽  
Xiaoqian Guan ◽  
Meijing Yang ◽  
Yee-Song Law ◽  
Chia Pao Voon ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Small Subunit ◽  
Purple Acid Phosphatase ◽  
Bimolecular Fluorescence Complementation ◽  
Differential Growth ◽  
Outer Membranes ◽  
C Terminus ◽  
Specific Proteins ◽  
Hydrophobic Motif ◽  
High Seed Yield

Arabidopsis thaliana purple acid phosphatase 2 (AtPAP2), which is anchored to the outer membranes of chloroplasts and mitochondria, affects carbon metabolism by modulating the import of some preproteins into chloroplasts and mitochondria. AtPAP9 bears a 72% amino acid sequence identity with AtPAP2, and both proteins carry a hydrophobic motif at their C-termini. Here, we show that AtPAP9 is a tail-anchored protein targeted to the outer membrane of chloroplasts. Yeast two-hybrid and bimolecular fluorescence complementation experiments demonstrated that both AtPAP9 and AtPAP2 bind to a small subunit of rubisco 1B (AtSSU1B) and a number of chloroplast proteins. Chloroplast import assays using [35S]-labeled AtSSU1B showed that like AtPAP2, AtPAP9 also plays a role in AtSSU1B import into chloroplasts. Based on these data, we propose that AtPAP9 and AtPAP2 perform overlapping roles in modulating the import of specific proteins into chloroplasts. Most plant genomes contain only one PAP-like sequence encoding a protein with a hydrophobic motif at the C-terminus. The presence of both AtPAP2 and AtPAP9 in the Arabidopsis genome may have arisen from genome duplication in Brassicaceae. Unlike AtPAP2 overexpression lines, the AtPAP9 overexpression lines did not exhibit early-bolting or high-seed-yield phenotypes. Their differential growth phenotypes could be due to the inability of AtPAP9 to be targeted to mitochondria, as the overexpression of AtPAP2 on mitochondria enhances the capacity of mitochondria to consume reducing equivalents.

scholarly journals A Balance between the Activities of Chloroplasts and Mitochondria Is Crucial for Optimal Plant Growth

Antioxidants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 935
Author(s):  
Zhou Xu ◽  
Renshan Zhang ◽  
Meijing Yang ◽  
Yee-Song Law ◽  
Feng Sun ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Growth ◽  
Seed Yield ◽  
Optimal Growth ◽  
Purple Acid Phosphatase ◽  
Outer Membranes ◽  
Transgenic Lines ◽  
Growth Promoting ◽  
High Level ◽  
Reducing Equivalents

Energy metabolism in plant cells requires a balance between the activities of chloroplasts and mitochondria, as they are the producers and consumers of carbohydrates and reducing equivalents, respectively. Recently, we showed that the overexpression of Arabidopsis thaliana purple acid phosphatase 2 (AtPAP2), a phosphatase dually anchored on the outer membranes of chloroplasts and mitochondria, can boost the plant growth and seed yield of Arabidopsis thaliana by coordinating the activities of both organelles. However, when AtPAP2 is solely overexpressed in chloroplasts, the growth-promoting effects are less optimal, indicating that active mitochondria are required for dissipating excess reducing equivalents from chloroplasts to maintain the optimal growth of plants. It is even more detrimental to plant productivity when AtPAP2 is solely overexpressed in mitochondria. Although these lines contain high level of adenosine triphosphate (ATP), they exhibit low leaf sucrose, low seed yield, and early senescence. These transgenic lines can be useful tools for studying how hyperactive chloroplasts or mitochondria affect the physiology of their counterparts and how they modify cellular metabolism and plant physiology.

scholarly journals Comparison of two Turnip mosaic virus P1 proteins in their ability to co-localize with the Arabidopsis thaliana G3BP-2 protein

Virus Genes ◽  
2021 ◽  
Vol 57 (2) ◽  
pp. 233-237
Author(s):  
Hendrik Reuper ◽  
Björn Krenz
Keyword(s):  
Arabidopsis Thaliana ◽  
Mosaic Virus ◽  
Specific Interaction ◽  
Viral Proteins ◽  
Turnip Mosaic Virus ◽  
Stress Conditions ◽  
C Terminus ◽  
Positive Sense ◽  
Key Factor ◽  
Large Host

AbstractTurnip mosaic virus (TuMV), belonging to the genus Potyvirus (family Potyviridae), has a large host range and consists of a single-stranded positive sense RNA genome encoding 12 proteins, including the P1 protease. This protein which is separated from the polyprotein by cis cleavage at its respective C-terminus, has been attributed with different functions during potyviral infection of plants. P1 of Turnip mosaic virus (P1-TuMV) harbors an FGSF-motif and FGSL-motif at its N-terminus. This motif is predicted to be a binding site for the host Ras GTPase-activating protein-binding protein (G3BP), which is a key factor for stress granule (SG) formation in mammalian systems and often targeted by viruses to inhibit SG formation. We therefore hypothesized that P1-TuMV might interact with G3BP to control and regulate plant SGs to optimize cellular conditions for the production of viral proteins. Here, we analyzed the co-localization of the Arabidopsis thaliana G3BP-2 with the P1 of two TuMV isolates, namely UK 1 and DEU 2. Surprisingly, P1-TuMV-DEU 2 co-localized with AtG3BP-2 under abiotic stress conditions, whereas P1-TuMV-UK 1 did not. AtG3BP-2::RFP showed strong SGs formation after stress, while P1-UK 1::eGFP maintained a chloroplastic signal under stress conditions, the signal of P1-DEU 2::eGFP co-localized with that of AtG3BP-2::RFP. This indicates a specific interaction between P1-DEU 2 and the AtG3BP family which is not solely based on the canonical interaction motifs.

IRON MAN interacts with BRUTUS to maintain iron homeostasis in Arabidopsis

2021 ◽  
Vol 118 (39) ◽  
pp. e2109063118
Author(s):  
Yang Li ◽  
Cheng Kai Lu ◽  
Chen Yang Li ◽  
Ri Hua Lei ◽  
Meng Na Pu ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Transcription Factors ◽  
Iron Homeostasis ◽  
Fe Deficiency ◽  
Small Peptides ◽  
Interaction Domain ◽  
C Terminus ◽  
Positive Regulators ◽  
Fe Homeostasis ◽  
And Function

IRON MAN (IMA) peptides, a family of small peptides, control iron (Fe) transport in plants, but their roles in Fe signaling remain unclear. BRUTUS (BTS) is a potential Fe sensor that negatively regulates Fe homeostasis by promoting the ubiquitin-mediated degradation of bHLH105 and bHLH115, two positive regulators of the Fe deficiency response. Here, we show that IMA peptides interact with BTS. The C-terminal parts of IMA peptides contain a conserved BTS interaction domain (BID) that is responsible for their interaction with the C terminus of BTS. Arabidopsis thaliana plants constitutively expressing IMA genes phenocopy the bts-2 mutant. Moreover, IMA peptides are ubiquitinated and degraded by BTS. bHLH105 and bHLH115 also share a BID, which accounts for their interaction with BTS. IMA peptides compete with bHLH105/bHLH115 for interaction with BTS, thereby inhibiting the degradation of these transcription factors by BTS. Genetic analyses suggest that bHLH105/bHLH115 and IMA3 have additive roles and function downstream of BTS. Moreover, the transcription of both BTS and IMA3 is activated directly by bHLH105 and bHLH115 under Fe-deficient conditions. Our findings provide a conceptual framework for understanding the regulation of Fe homeostasis: IMA peptides protect bHLH105/bHLH115 from degradation by sequestering BTS, thereby activating the Fe deficiency response.

scholarly journals The vaccinia virus F12L protein is associated with intracellular enveloped virus particles and is required for their egress to the cell surface

2002 ◽  
Vol 83 (1) ◽  
pp. 195-207 ◽  
Author(s):  
Henriette van Eijl ◽  
Michael Hollinshead ◽  
Gaener Rodger ◽  
Wei-Hong Zhang ◽  
Geoffrey L. Smith
Keyword(s):  
Cell Surface ◽  
Vaccinia Virus ◽  
Virus Particles ◽  
Enveloped Virus ◽  
Virus Morphogenesis ◽  
C Terminus ◽  
Specific Proteins ◽  
Infected Cells ◽  
Mature Virus ◽  
Confocal And Electron Microscopy

The vaccinia virus (VV) F12L gene encodes a 65 kDa protein that is expressed late during infection and is important for plaque formation, EEV production and virulence. Here we have used a recombinant virus (vF12LHA) in which the F12L protein is tagged at the C terminus with an epitope recognized by a monoclonal antibody to determine the location of F12L in infected cells and whether it associates with virions. Using confocal and electron microscopy we show that the F12L protein is located on intracellular enveloped virus (IEV) particles, but is absent from immature virions (IV), intracellular mature virus (IMV) and cell-associated enveloped virus (CEV). In addition, F12L shows co-localization with endosomal compartments and microtubules. F12L did not co-localize with virions attached to actin tails, providing further evidence that actin tails are associated with CEV but not IEV particles. In vΔF12L-infected cells, virus morphogenesis was arrested after the formation of IEV particles, so that the movement of these virions to the cell surface was inhibited and CEV particles were not found. Previously, virus mutants lacking IEV- or EEV-specific proteins were either unable to make IEV particles (vΔF13L and vΔB5R), or were unable to form actin tails after formation of CEV particles (vΔA36R, vΔA33R, vΔA34R). The F12L deletion mutant therefore defines a new stage in the morphogenic pathway and the F12L protein is implicated as necessary for microtubule-mediated egress of IEV particles to the cell surface.

scholarly journals Identification of client iron–sulfur proteins of the chloroplastic NFU2 transfer protein in Arabidopsis thaliana

2020 ◽  
Vol 71 (14) ◽  
pp. 4171-4187 ◽  
Author(s):  
Nathalie Berger ◽  
Florence Vignols ◽  
Jonathan Przybyla-Toscano ◽  
Mélanie Roland ◽  
Valérie Rofidal ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
De Novo ◽  
Bimolecular Fluorescence Complementation ◽  
In Planta ◽  
Chlorophyll Metabolism ◽  
Transfer Protein ◽  
Iron Sulfur ◽  
Bimolecular Fluorescence Complementation Assay ◽  
Client Proteins ◽  
S Proteins

Abstract Iron–sulfur (Fe-S) proteins have critical functions in plastids, notably participating in photosynthetic electron transfer, sulfur and nitrogen assimilation, chlorophyll metabolism, and vitamin or amino acid biosynthesis. Their maturation relies on the so-called SUF (sulfur mobilization) assembly machinery. Fe-S clusters are synthesized de novo on a scaffold protein complex and then delivered to client proteins via several transfer proteins. However, the maturation pathways of most client proteins and their specificities for transfer proteins are mostly unknown. In order to decipher the proteins interacting with the Fe-S cluster transfer protein NFU2, one of the three plastidial representatives found in Arabidopsis thaliana, we performed a quantitative proteomic analysis of shoots, roots, and seedlings of nfu2 plants, combined with NFU2 co-immunoprecipitation and binary yeast two-hybrid experiments. We identified 14 new targets, among which nine were validated in planta using a binary bimolecular fluorescence complementation assay. These analyses also revealed a possible role for NFU2 in the plant response to desiccation. Altogether, this study better delineates the maturation pathways of many chloroplast Fe-S proteins, considerably extending the number of NFU2 clients. It also helps to clarify the respective roles of the three NFU paralogs NFU1, NFU2, and NFU3.

scholarly journals FRUITFULL Is a Repressor of Apical Hook Opening in Arabidopsis thaliana

2020 ◽  
Vol 21 (17) ◽  
pp. 6438
Author(s):  
Miriam Führer ◽  
Angelika Gaidora ◽  
Peter Venhuizen ◽  
Jedrzej Dobrogojski ◽  
Chloé Béziat ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
In Silico ◽  
Target Genes ◽  
Growth Promotion ◽  
In Silico Analysis ◽  
Regulatory Elements ◽  
Suitable Model ◽  
Differential Growth ◽  
Apical Hook ◽  
Growth Transitions

Plants adjust their architecture to a constantly changing environment, requiring adaptation of differential growth. Despite their importance, molecular switches, which define growth transitions, are largely unknown. Apical hook development in dark grown Arabidopsis thaliana (A. thaliana) seedlings serves as a suitable model for differential growth transition in plants. Here, we show that the phytohormone auxin counteracts the light-induced growth transition during apical hook opening. We, subsequently, identified genes which are inversely regulated by light and auxin. We used in silico analysis of the regulatory elements in this set of genes and subsequently used natural variation in gene expression to uncover correlations between underlying transcription factors and the in silico predicted target genes. This approach uncovered that MADS box transcription factor AGAMOUS-LIKE 8 (AGL8)/FRUITFULL (FUL) modulates apical hook opening. Our data shows that transient FUL expression represses the expression of growth stimulating genes during early phases of apical hook development and therewith guards the transition to growth promotion for apical hook opening. Here, we propose a role for FUL in setting tissue identity, thereby regulating differential growth during apical hook development.

scholarly journals Chimeric small subunit inhibitors of mammalian ribonucleotide reductase: a dual function for the R2 C-terminus?

1998 ◽  
Vol 11 (3) ◽  
pp. 219-224 ◽  
Author(s):  
C. S. Hamann ◽  
S. Lentainge ◽  
L. S. Li ◽  
J. S. Salem ◽  
F. D. Yang ◽  
...  
Keyword(s):  
Ribonucleotide Reductase ◽  
Small Subunit ◽  
Dual Function ◽  
C Terminus

scholarly journals AtRsgA from Arabidopsis thaliana is important for maturation of the small subunit of the chloroplast ribosome

2018 ◽  
Vol 96 (2) ◽  
pp. 404-420 ◽  
Author(s):  
Marcin Janowski ◽  
Reimo Zoschke ◽  
Lars B. Scharff ◽  
Silvia Martinez Jaime ◽  
Camilla Ferrari ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Small Subunit

scholarly journals Functional requirements of AID’s higher order structures and their interaction with RNA-binding proteins

2016 ◽  
Vol 113 (11) ◽  
pp. E1545-E1554 ◽  
Author(s):  
Samiran Mondal ◽  
Nasim A. Begum ◽  
Wenjun Hu ◽  
Tasuku Honjo
Keyword(s):  
Dna Cleavage ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Somatic Hypermutation ◽  
Cytidine Deaminase ◽  
Bimolecular Fluorescence Complementation ◽  
Functional Requirements ◽  
C Terminus ◽  
Gradient Fractionation

Activation-induced cytidine deaminase (AID) is essential for the somatic hypermutation (SHM) and class-switch recombination (CSR) of Ig genes. Although both the N and C termini of AID have unique functions in DNA cleavage and recombination, respectively, during SHM and CSR, their molecular mechanisms are poorly understood. Using a bimolecular fluorescence complementation (BiFC) assay combined with glycerol gradient fractionation, we revealed that the AID C terminus is required for a stable dimer formation. Furthermore, AID monomers and dimers form complexes with distinct heterogeneous nuclear ribonucleoproteins (hnRNPs). AID monomers associate with DNA cleavage cofactor hnRNP K whereas AID dimers associate with recombination cofactors hnRNP L, hnRNP U, and Serpine mRNA-binding protein 1. All of these AID/ribonucleoprotein associations are RNA-dependent. We propose that AID’s structure-specific cofactor complex formations differentially contribute to its DNA-cleavage and recombination functions.

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