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Nam JC, Bhatt PS, Bonnard A, Pujara D, Kang HG. Arabidopsis MORC1 and MED9 Interact to Regulate Defense Gene Expression and Plant Fitness. THE PLANT PATHOLOGY JOURNAL 2024; 40:438-450. [PMID: 39397299 PMCID: PMC11471927 DOI: 10.5423/ppj.oa.07.2024.0107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Revised: 08/09/2024] [Accepted: 08/11/2024] [Indexed: 10/15/2024]
Abstract
Arabidopsis MORC1 (Microrchidia) is required for multiple levels of immunity. We identified 14 MORC1-interacting proteins (MIPs) via yeast two-hybrid screening, eight of which have confirmed or putative nuclear-associated functions. While a few MIP mutants displayed altered bacterial resistance, MIP13 was unusual. The MIP13 mutant was susceptible to Pseudomonas syringae, but when combined with morc1/2, it regained wild-type resistance; notably, morc1/2 is susceptible to the same pathogen. MIP13 encodes MED9, a mediator complex component that interfaces with RNA polymerase II and transcription factors. Expression analysis of defense genes PR1, PR2, and PR5 in response to avirulent P. syringae revealed that morc1/2 med9 expressed these genes in a slow but sustained manner, unlike its lower-order mutants. This expression pattern may explain the restored resistance and suggests that the interplay of MORC1/2 and MED9 might be important in curbing defense responses to maintain fitness. Indeed, repeated challenges with avirulent P. syringae triggered significant growth inhibition in morc1/2 med9, indicating that MED9 and MORC1 may play an important role in balancing defense and growth. Furthermore, the in planta interaction of MED9 and MORC1 occurred 24 h, not 6 h, postinfection, suggesting that the interaction functions late in the defense signaling. Our study reveals a complex interplay between MORC1 and MED9 in maintaining an optimal balance between defense and growth in Arabidopsis.
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Affiliation(s)
- Ji Chul Nam
- Department of Biology, Texas State University, 600 University Dr., San Marcos, TX 78666, USA
| | - Padam Shekhar Bhatt
- Department of Biology, Texas State University, 600 University Dr., San Marcos, TX 78666, USA
| | | | - Dinesh Pujara
- Department of Biology, Texas State University, 600 University Dr., San Marcos, TX 78666, USA
| | - Hong-Gu Kang
- Department of Biology, Texas State University, 600 University Dr., San Marcos, TX 78666, USA
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2
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Wang H, Tang X, Liu Y. SlCK2α as a novel substrate for CRL4 E3 ligase regulates fruit size through maintenance of cell division homeostasis in tomato. PLANTA 2023; 257:38. [PMID: 36645501 DOI: 10.1007/s00425-023-04070-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 01/04/2023] [Indexed: 06/17/2023]
Abstract
This study unravels a novel regulatory module (CRL4-CK2α-CDK2) involving fruit size control by mediating cell division homeostasis (SlCK2α and SlCDK2) in tomato. Fruit size is one of the crucial agronomical traits for crop production. UV-damaged DNA binding protein 1 (DDB1), a core component of Cullin4-RING E3 ubiquitin ligase complex (CRL4), has been identified as a negative regulator of fruit size in tomato (Solanum lycopersicum). However, the underlying molecular mechanism remains largely unclear. Here, we report the identification and characterization of a SlDDB1-interacting protein putatively involving fruit size control through regulating cell proliferation in tomato. It is a tomato homolog SlCK2α, the catalytic subunit of the casein kinase 2 (CK2), identified by yeast two-hybrid (Y2H) assays. The interaction between SlDDB1 and SlCK2α was demonstrated by bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP). RNA interference (RNAi) and CRISPR/Cas9-based mutant analyses showed that lack of SlCK2α resulted in reduction of fruit size with reduced cell number, suggesting it is a positive regulator on fruit size by promoting cell proliferation. We also showed SlDDB1 is required to ubiquitinate SlCK2α and negatively regulate its stability through 26S proteasome-mediated degradation. Furthermore, we found that a tomato homolog of cell division protein kinase 2 (SlCDK2) could interact with and specifically be phosphorylated by SlCK2α, resulting in an increase of SlCDK2 protein stability. CRISPR/Cas9-based genetic evidence showed that SlCDK2 is also a positive regulator of fruit size by influencing cell division in tomato. Taken together, our findings, thus, unravel a novel regulatory module CRL4-CK2α-CDK2 in finely modulating cell division homeostasis and the consequences on fruit size.
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Affiliation(s)
- Hongtao Wang
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, 230009, China
| | - Xiaofeng Tang
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, 230009, China.
| | - Yongsheng Liu
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei, 230009, China.
- School of Horticulture and State Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, 230036, China.
- Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, 610064, China.
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3
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Zhu J, Wang WS, Yan DW, Hong LW, Li TT, Gao X, Yang YH, Ren F, Lu YT, Yuan TT. CK2 promotes jasmonic acid signaling response by phosphorylating MYC2 in Arabidopsis. Nucleic Acids Res 2022; 51:619-630. [PMID: 36546827 PMCID: PMC9881174 DOI: 10.1093/nar/gkac1213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 10/19/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
Jasmonic acid (JA) signaling plays a pivotal role in plant development and defense. MYC2 is a master transcription factor in JA signaling, and was found to be phosphorylated and negatively regulated by MAP kinase and receptor-like kinase. However, the kinases that positively regulate MYC2 through phosphorylation and promote MYC2-mediated activation of JA response have not been identified. Here, we identified CK2 as a kinase that phosphorylates MYC2 and thus regulates the JA signaling. CK2 holoenzyme can interact with MYC2 using its regulatory subunits and phosphorylate MYC2 at multiple sites with its catalytic subunits. Inhibition of CK2 activity in a dominant-negative plant line, CK2mut, repressed JA response. On the other hand, increasing CK2 activity by overexpression of CKB4, a regulatory subunit gene of CK2, enhanced JA response in a MYC2-dependent manner. Substitution of the Ser and Thr residues at phosphorylation sites of MYC2 by CK2 with Ala impaired MYC2 function in activating JA response. Further investigations evidenced that CK2 facilitated the JA-induced increase of MYC2 binding to the promoters of JA-responsive genes in vivo. Our study demonstrated that CK2 plays a positive role in JA signaling, and reveals a previously undiscovered mechanism that regulates MYC2 function.
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Affiliation(s)
| | | | - Da-Wei Yan
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Li-Wei Hong
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Ting-Ting Li
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Xiang Gao
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430072, China
| | - Yun-Huang Yang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, National Center for Magnetic Resonance in Wuhan, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Feng Ren
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Ying-Tang Lu
- Correspondence may also be addressed to Ying-Tang Lu. Tel: +86 27 68752619; Fax: +86 27 68753551;
| | - Ting-Ting Yuan
- To whom correspondence should be addressed. Tel: +86 27 68752619; Fax: +86 27 68753551;
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4
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Wang G, Gao G, Yang X, Yang X, Ma P. Casein kinase CK2 structure and activities in plants. JOURNAL OF PLANT PHYSIOLOGY 2022; 276:153767. [PMID: 35841742 DOI: 10.1016/j.jplph.2022.153767] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 07/10/2022] [Accepted: 07/10/2022] [Indexed: 06/15/2023]
Abstract
Casein kinase CK2 is a highly conserved serine/threonine protein kinase and exists in all eukaryotes. It has been demonstrated to be widely involved in the biological processes of plants. The CK2 holoenzyme is a heterotetramer consisting of two catalytic subunits (α and/or α') and two regulatory subunits (β). CK2 in plants is generally encoded by multiple genes, with monomeric and oligomeric forms present in the tissue. Various subunit genes of CK2 have been cloned and characterized from Arabidopsis thaliana, tobacco, maize, wheat, tomato, and other plants. This paper reviews the structural features of CK2, provides a clear classification of its physiological functions and mechanisms of action, and elaborates on the regulation of CK2 activity to provide a knowledge base for subsequent studies of CK2 in plants.
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Affiliation(s)
- Guanfeng Wang
- College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Geling Gao
- College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Xiangna Yang
- College of Life Sciences, Northwest A&F University, Yangling, 712100, China
| | - Xiangdong Yang
- Institute of Agricultural Biotechnology, Jilin Academy of Agricultural Sciences, Changchun, 130033, China.
| | - Pengda Ma
- College of Life Sciences, Northwest A&F University, Yangling, 712100, China.
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5
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Niu Y, Huang X, He Z, Zhang Q, Meng H, Shi H, Feng B, Zhou Y, Zhang J, Lu G, Wang Z, Zhang W, Tang D, Wang M. Phosphorylation of OsTGA5 by casein kinase II compromises its suppression of defense-related gene transcription in rice. THE PLANT CELL 2022; 34:3425-3442. [PMID: 35642941 PMCID: PMC9421590 DOI: 10.1093/plcell/koac164] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 04/25/2022] [Indexed: 06/15/2023]
Abstract
Plants manage the high cost of immunity activation by suppressing the expression of defense genes during normal growth and rapidly switching them on upon pathogen invasion. TGAs are key transcription factors controlling the expression of defense genes. However, how TGAs function, especially in monocot plants like rice with continuously high levels of endogenous salicylic acid (SA) remains elusive. In this study, we characterized the role of OsTGA5 as a negative regulator of rice resistance against blast fungus by transcriptionally repressing the expression of various defense-related genes. Moreover, OsTGA5 repressed PTI responses and the accumulation of endogenous SA. Importantly, we showed that the nucleus-localized casein kinase II (CK2) complex interacts with and phosphorylates OsTGA5 on Ser-32, which reduces the affinity of OsTGA5 for the JIOsPR10 promoter, thereby alleviating the repression of JIOsPR10 transcription and increasing rice resistance. Furthermore, the in vivo phosphorylation of OsTGA5 Ser-32 was enhanced by blast fungus infection. The CK2 α subunit, depending on its kinase activity, positively regulated rice defense against blast fungus. Taken together, our results provide a mechanism for the role of OsTGA5 in negatively regulating the transcription of defense-related genes in rice and the repressive switch imposed by nuclear CK2-mediated phosphorylation during blast fungus invasion.
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Affiliation(s)
- Yuqing Niu
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian University Key Laboratory for Plant–Microbe Interaction, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiaoguang Huang
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian University Key Laboratory for Plant–Microbe Interaction, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zexue He
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, JiangSu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing 210095, China
| | - Qingqing Zhang
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian University Key Laboratory for Plant–Microbe Interaction, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Han Meng
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian University Key Laboratory for Plant–Microbe Interaction, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Hua Shi
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian University Key Laboratory for Plant–Microbe Interaction, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Baomin Feng
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian University Key Laboratory for Plant–Microbe Interaction, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | | | - Jianfu Zhang
- Rice Research Institute, Fujian Academy of Agricultural Sciences, Fuzhou 350019, China
| | - Guodong Lu
- Key Laboratory of Biopesticides and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Zonghua Wang
- Institute of Oceanography, Minjiang University, Fuzhou 350108, China
| | - Wenli Zhang
- State Key Laboratory for Crop Genetics and Germplasm Enhancement, JiangSu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, Nanjing 210095, China
| | - Dingzhong Tang
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Fujian University Key Laboratory for Plant–Microbe Interaction, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Mo Wang
- Author for correspondence: (Y.Z.), (M.W.)
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6
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Tomaž Š, Gruden K, Coll A. TGA transcription factors-Structural characteristics as basis for functional variability. FRONTIERS IN PLANT SCIENCE 2022; 13:935819. [PMID: 35958211 PMCID: PMC9360754 DOI: 10.3389/fpls.2022.935819] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
TGA transcription factors are essential regulators of various cellular processes, their activity connected to different hormonal pathways, interacting proteins and regulatory elements. Belonging to the basic region leucine zipper (bZIP) family, TGAs operate by binding to their target DNA sequence as dimers through a conserved bZIP domain. Despite sharing the core DNA-binding sequence, the TGA paralogues exert somewhat different DNA-binding preferences. Sequence variability of their N- and C-terminal protein parts indicates their importance in defining TGA functional specificity through interactions with diverse proteins, affecting their DNA-binding properties. In this review, we provide a short and concise summary on plant TGA transcription factors from a structural point of view, including the relation of their structural characteristics to their functional roles in transcription regulation.
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Affiliation(s)
- Špela Tomaž
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
- Jožef Stefan International Postgraduate School, Ljubljana, Slovenia
| | - Kristina Gruden
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
| | - Anna Coll
- Department of Biotechnology and Systems Biology, National Institute of Biology, Ljubljana, Slovenia
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7
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Effects of Abscisic Acid and Salicylic Acid on Gene Expression in the Antiviral RNA Silencing Pathway in Arabidopsis. Int J Mol Sci 2019; 20:ijms20102538. [PMID: 31126102 PMCID: PMC6566719 DOI: 10.3390/ijms20102538] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 05/19/2019] [Accepted: 05/21/2019] [Indexed: 02/06/2023] Open
Abstract
The RNA silencing pathways modulate responses to certain stresses, and can be partially tuned by several hormones such as salicylic acid (SA) and abscisic acid (ABA). Although SA and ABA are often antagonistic and often modulate different stress responses, they have similar effects on virus resistance, which are partially achieved through the antiviral RNA silencing pathway. Whether they play similar roles in regulating the RNA silencing pathway is unclear. By employing coexpression and promoter analyses, we found that some ABA- and SA-related transcription factors (TFs) are coexpressed with several AGO, DCL, and RDR genes, and have multiple binding sites for the identified TFs in the queried promoters. ABA and SA are antagonistic with respect to the expression of AGO1 and RDRs because ABA was able to induce these genes only in the SA mutant. Nevertheless, both hormones showed similarities in the regulation of other genes, for example, the induction of AGO2 by ABA was SA-dependent, indicating that ABA acts upstream of SA in this regulation. We inferred that the similar effects of ABA and SA on some genes resulted in the redundancy of their roles in resistance to bamboo mosaic virus, but that the two hormones are antagonistic with respect to other genes unrelated to their biosynthesis pathways.
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8
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Weinman LM, Running KLD, Carey NS, Stevenson EJ, Swaney DL, Chow BY, Krogan NJ, Krogan NT. TCO, a Putative Transcriptional Regulator in Arabidopsis, Is a Target of the Protein Kinase CK2. Int J Mol Sci 2018; 20:ijms20010099. [PMID: 30597831 PMCID: PMC6337506 DOI: 10.3390/ijms20010099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 12/26/2018] [Accepted: 12/26/2018] [Indexed: 11/16/2022] Open
Abstract
As multicellular organisms grow, spatial and temporal patterns of gene expression are strictly regulated to ensure that developmental programs are invoked at appropriate stages. In this work, we describe a putative transcriptional regulator in Arabidopsis, TACO LEAF (TCO), whose overexpression results in the ectopic activation of reproductive genes during vegetative growth. Isolated as an activation-tagged allele, tco-1D displays gene misexpression and phenotypic abnormalities, such as curled leaves and early flowering, characteristic of chromatin regulatory mutants. A role for TCO in this mode of transcriptional regulation is further supported by the subnuclear accumulation patterns of TCO protein and genetic interactions between tco-1D and chromatin modifier mutants. The endogenous expression pattern of TCO and gene misregulation in tco loss-of-function mutants indicate that this factor is involved in seed development. We also demonstrate that specific serine residues of TCO protein are targeted by the ubiquitous kinase CK2. Collectively, these results identify TCO as a novel regulator of gene expression whose activity is likely influenced by phosphorylation, as is the case with many chromatin regulators.
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Affiliation(s)
- Laina M Weinman
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Katherine L D Running
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Nicholas S Carey
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Erica J Stevenson
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA 94158, USA.
| | - Danielle L Swaney
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA 94158, USA.
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA.
| | - Brenda Y Chow
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
| | - Nevan J Krogan
- Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, CA 94158, USA.
- Quantitative Biosciences Institute (QBI), University of California, San Francisco, CA 94158, USA.
| | - Naden T Krogan
- Department of Biology, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016, USA.
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9
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Liu W, Lin Z, Liu Y, Lin Y, Xu X, Lai Z. Genome-wide identification and characterization of the CKII gene family in the cultivated banana cultivar (Musa spp. cv Tianbaojiao) and the wild banana (Musa itinerans). PLoS One 2018; 13:e0200149. [PMID: 29995937 PMCID: PMC6040749 DOI: 10.1371/journal.pone.0200149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/20/2018] [Indexed: 11/19/2022] Open
Abstract
Plant casein kinase II (CKII) plays an essential role in regulating plant growth and development, and responses to biotic and abiotic stresses. Here, we report the identification and characterization of the CKII family genes in Musa spp. cv. ‘Tianbaojiao’ (AAA group) and the wild banana (Musa itinerans). The 13 cDNA sequences of the CKII family members were identified both in ‘Tianbaojiao’ and wild banana, respectively. The differences between CKII α and CKII β members are corroborated through the subcellular localizations, phosphorylation sites and gene structures. The cloning of CKII β-like-2 gDNA sequences in wild banana and ‘Tianbaojiao’ and the analysis of gene structures showed MiCKIIβ-like-2b and MaCKIIβ-like-2 are likely alternatively spliced transcripts, which were derived from the alternative splicing events that involved exon deletion. The qPCR validation showed differential expression CKII family members in response to cold stress and also in all tested tissues (leaf, pseudostem and root) of wild banana. In particular, the normal transcript MiCKIIβ-like-2a was highly expressed in response to cold stress in wild banana; oppositely, the alternatively spliced transcript MiCKIIβ-like-2b was quite lowly expressed. The complex origin and long-term evolution of Musa lineage might explain the alternative splicing events of CKII β-like-2.
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Affiliation(s)
- Weihua Liu
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Zhengchun Lin
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Yanying Liu
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Yuling Lin
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - XuHan Xu
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Zhongxiong Lai
- Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- * E-mail:
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10
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Findling S, Stotz HU, Zoeller M, Krischke M, Zander M, Gatz C, Berger S, Mueller MJ. TGA2 signaling in response to reactive electrophile species is not dependent on cysteine modification of TGA2. PLoS One 2018; 13:e0195398. [PMID: 29608605 PMCID: PMC5880405 DOI: 10.1371/journal.pone.0195398] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 03/21/2018] [Indexed: 01/18/2023] Open
Abstract
Reactive electrophile species (RES), including prostaglandins, phytoprostanes and 12-oxo phytodienoic acid (OPDA), activate detoxification responses in plants and animals. However, the pathways leading to the activation of defense reactions related to abiotic or biotic stress as a function of RES formation, accumulation or treatment are poorly understood in plants. Here, the thiol-modification of proteins, including the RES-activated basic region/leucine zipper transcription factor TGA2, was studied. TGA2 contains a single cysteine residue (Cys186) that was covalently modified by reactive cyclopentenones but not required for induction of detoxification genes in response to OPDA or prostaglandin A1. Activation of the glutathione-S-transferase 6 (GST6) promoter was responsive to cyclopentenones but not to unreactive cyclopentanones, including jasmonic acid suggesting that thiol reactivity of RES is important to activate the TGA2-dependent signaling pathway resulting in GST6 activation We show that RES modify thiols in numerous proteins in vivo, however, thiol reactivity alone appears not to be sufficient for biological activity as demonstrated by the failure of several membrane permeable thiol reactive reagents to activate the GST6 promoter.
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Affiliation(s)
- Simone Findling
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, Wuerzburg, Germany
| | - Henrik U. Stotz
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, Wuerzburg, Germany
| | - Maria Zoeller
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, Wuerzburg, Germany
| | - Markus Krischke
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, Wuerzburg, Germany
| | - Mark Zander
- Albrecht-von-Haller Institute for Plant Sciences, Georg-August-University of Goettingen, Goettingen, Germany
| | - Christiane Gatz
- Albrecht-von-Haller Institute for Plant Sciences, Georg-August-University of Goettingen, Goettingen, Germany
| | - Susanne Berger
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, Wuerzburg, Germany
| | - Martin J. Mueller
- Julius-von-Sachs-Institute of Biosciences, Biocenter, Pharmaceutical Biology, University of Wuerzburg, Wuerzburg, Germany
- * E-mail:
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11
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Rayapuram N, Bigeard J, Alhoraibi H, Bonhomme L, Hesse AM, Vinh J, Hirt H, Pflieger D. Quantitative Phosphoproteomic Analysis Reveals Shared and Specific Targets of Arabidopsis Mitogen-Activated Protein Kinases (MAPKs) MPK3, MPK4, and MPK6. Mol Cell Proteomics 2017; 17:61-80. [PMID: 29167316 DOI: 10.1074/mcp.ra117.000135] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 10/27/2017] [Indexed: 01/14/2023] Open
Abstract
In Arabidopsis, mitogen-activated protein kinases MPK3, MPK4, and MPK6 constitute essential relays for a variety of functions including cell division, development and innate immunity. Although some substrates of MPK3, MPK4 and MPK6 have been identified, the picture is still far from complete. To identify substrates of these MAPKs likely involved in cell division, growth and development we compared the phosphoproteomes of wild-type and mpk3, mpk4, and mpk6. To study the function of these MAPKs in innate immunity, we analyzed their phosphoproteomes following microbe-associated molecular pattern (MAMP) treatment. Partially overlapping substrates were retrieved for all three MAPKs, showing target specificity to one, two or all three MAPKs in different biological processes. More precisely, our results illustrate the fact that the entity to be defined as a specific or a shared substrate for MAPKs is not a phosphoprotein but a particular (S/T)P phosphorylation site in a given protein. One hundred fifty-two peptides were identified to be differentially phosphorylated in response to MAMP treatment and/or when compared between genotypes and 70 of them could be classified as putative MAPK targets. Biochemical analysis of a number of putative MAPK substrates by phosphorylation and interaction assays confirmed the global phosphoproteome approach. Our study also expands the set of MAPK substrates to involve other protein kinases, including calcium-dependent (CDPK) and sugar nonfermenting (SnRK) protein kinases.
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Affiliation(s)
- Naganand Rayapuram
- From the ‡Center for Desert Agriculture, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Jean Bigeard
- §Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France.,¶Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405 Orsay, France
| | - Hanna Alhoraibi
- From the ‡Center for Desert Agriculture, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Ludovic Bonhomme
- ‖UMR INRA/UBP Génétique, Diversité et Écophysiologie des Céréales, Université de Clermont-Ferrand, 63039 Clermont-Ferrand, France
| | - Anne-Marie Hesse
- **CEA, BIG-BGE-EDyP, U1038 Inserm/CEA/UGA, 38000 Grenoble, France
| | - Joëlle Vinh
- ‡‡ESPCI Paris, PSL Research University, Spectrométrie de Masse Biologique et Protéomique (SMBP), CNRS USR 3149, 10 rue Vauquelin, F75231 Paris cedex05, France
| | - Heribert Hirt
- From the ‡Center for Desert Agriculture, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia;
| | - Delphine Pflieger
- **CEA, BIG-BGE-EDyP, U1038 Inserm/CEA/UGA, 38000 Grenoble, France.,§§CNRS, LAMBE UMR 8587, Université d'Evry Val d'Essonne, Evry, France
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12
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de Jonge J, Hofius D, Hennig L. Salicylic acid interferes with GFP fluorescence in vivo. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1689-1696. [PMID: 28369601 PMCID: PMC5441896 DOI: 10.1093/jxb/erx031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Fluorescent proteins have become essential tools for cell biologists. They are routinely used by plant biologists for protein and promoter fusions to infer protein localization, tissue-specific expression and protein abundance. When studying the effects of biotic stress on chromatin, we unexpectedly observed a decrease in GFP signal intensity upon salicylic acid (SA) treatment in Arabidopsis lines expressing histone H1-GFP fusions. This GFP signal decrease was dependent on SA concentration. The effect was not specific to the linker histone H1-GFP fusion but was also observed for the nucleosomal histone H2A-GFP fusion. This result prompted us to investigate a collection of fusion proteins, which included different promoters, subcellular localizations and fluorophores. In all cases, fluorescence signals declined strongly or disappeared after SA application. No changes were detected in GFP-fusion protein abundance when fluorescence signals were lost indicating that SA does not interfere with protein stability but GFP fluorescence. In vitro experiments showed that SA caused GFP fluorescence reduction only in vivo but not in vitro, suggesting that SA requires cellular components to cause fluorescence reduction. Together, we conclude that SA can interfere with the fluorescence of various GFP-derived reporter constructs in vivo. Assays that measure relocation or turnover of GFP-tagged proteins upon SA treatment should therefore be evaluated with caution.
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Affiliation(s)
- Jennifer de Jonge
- Swedish University of Agricultural Sciences, Department of Plant Biology and Linnean Center for Plant Biology, PO Box 7080, SE-75007 Uppsala, Sweden
| | - Daniel Hofius
- Swedish University of Agricultural Sciences, Department of Plant Biology and Linnean Center for Plant Biology, PO Box 7080, SE-75007 Uppsala, Sweden
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13
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Bordiya Y, Zheng Y, Nam JC, Bonnard AC, Choi HW, Lee BK, Kim J, Klessig DF, Fei Z, Kang HG. Pathogen Infection and MORC Proteins Affect Chromatin Accessibility of Transposable Elements and Expression of Their Proximal Genes in Arabidopsis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:674-687. [PMID: 27482822 DOI: 10.1094/mpmi-01-16-0023-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
To assess the role of MORC1 in epigenetics in relation to plant immunity, genome-wide chromatin accessibility was compared between mock- or Pseudomonas syringae pv. tomato-inoculated wild type (WT) Arabidopsis, the morc1/2 double mutant, or both. Most changes in chromatin accessibility, scored by DNase I hypersensitive sites (DHSs), were located in the promoters of genes and transposable elements (TEs). Comparisons between morc1/2 and WT receiving the same treatment revealed differential DHSs (dDHSs) predominantly associated with heterochromatic TEs. By contrast, comparisons between mock- and P. syringae pv. tomato-inoculated plants from the same genotype showed dDHSs associated with biotic and abiotic stress-related genes; a smaller but significant population was in TEs. Moreover, many defense genes, including PR-1, PR-2, and PR-5, were proximal to P. syringae pv. tomato-induced, TE-associated dDHSs. A random subset of these defense genes showed moderately delayed or reduced expression or both in P. syringae pv. tomato-infected morc1/2 as compared with WT. MORC1 was physically bound to chromatin in a P. syringae pv. tomato infection-responsive manner at sites dispersed throughout the genome. Notably, silencing of TE-associated dDHSs proximal to these infection-induced, MORC1-interacting sites led to significant suppression of P. syringae pv. tomato-induced transcription of adjacent defense genes, including PR-1. These results provide evidence that MORC1 is associated with TEs and suggest that a subset of these TEs may help regulate their proximal defense genes.
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Affiliation(s)
- Yogendra Bordiya
- 1 Department of Biology, Texas State University, San Marcos, TX, U.S.A
| | - Yi Zheng
- 2 Boyce Thompson Institute for Plant Research, Ithaca, NY, U.S.A
| | - Ji-Chul Nam
- 1 Department of Biology, Texas State University, San Marcos, TX, U.S.A
| | - April C Bonnard
- 1 Department of Biology, Texas State University, San Marcos, TX, U.S.A
| | - Hyong Woo Choi
- 2 Boyce Thompson Institute for Plant Research, Ithaca, NY, U.S.A
| | - Bum-Kyu Lee
- 3 Department of Molecular Biosciences, The University of Texas at Austin, U.S.A.; and
| | - Jonghwan Kim
- 3 Department of Molecular Biosciences, The University of Texas at Austin, U.S.A.; and
| | - Daniel F Klessig
- 2 Boyce Thompson Institute for Plant Research, Ithaca, NY, U.S.A
| | - Zhangjun Fei
- 2 Boyce Thompson Institute for Plant Research, Ithaca, NY, U.S.A
- 4 USDA Robert W. Holley Center for Agriculture and Health, Tower Road, Ithaca, NY, U.S.A
| | - Hong-Gu Kang
- 1 Department of Biology, Texas State University, San Marcos, TX, U.S.A
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14
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Phosphorylation Affects DNA-Binding of the Senescence-Regulating bZIP Transcription Factor GBF1. PLANTS 2015; 4:691-709. [PMID: 27135347 PMCID: PMC4844403 DOI: 10.3390/plants4030691] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 08/12/2015] [Accepted: 09/08/2015] [Indexed: 11/28/2022]
Abstract
Massive changes in the transcriptome of Arabidopsis thaliana during onset and progression of leaf senescence imply a central role for transcription factors. While many transcription factors are themselves up- or down-regulated during senescence, the bZIP transcription factor G-box-binding factor 1 (GBF1/bZIP41) is constitutively expressed in Arabidopsis leaf tissue but at the same time triggers the onset of leaf senescence, suggesting posttranscriptional mechanisms for senescence-specific GBF1 activation. Here we show that GBF1 is phosphorylated by the threonine/serine CASEIN KINASE II (CKII) in vitro and that CKII phosphorylation had a negative effect on GBF1 DNA-binding to G-boxes of two direct target genes, CATALASE2 and RBSCS1a. Phosphorylation mimicry at three serine positions in the basic region of GBF1 also had a negative effect on DNA-binding. Kinase assays revealed that CKII phosphorylates at least one serine in the basic domain but has additional phosphorylation sites outside this domain. Two different ckII α subunit1 and one α subunit2 T-DNA insertion lines showed no visible senescence phenotype, but in all lines the expression of the senescence marker gene SAG12 was remarkably diminished. A model is presented suggesting that senescence-specific GBF1 activation might be achieved by lowering the phosphorylation of GBF1 by CKII.
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15
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Vilela B, Pagès M, Riera M. Emerging roles of protein kinase CK2 in abscisic acid signaling. FRONTIERS IN PLANT SCIENCE 2015; 6:966. [PMID: 26579189 PMCID: PMC4630567 DOI: 10.3389/fpls.2015.00966] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 10/22/2015] [Indexed: 05/02/2023]
Abstract
The phytohormone abscisic acid (ABA) regulates many aspects of plant growth and development as well as responses to multiple stresses. Post-translational modifications such as phosphorylation or ubiquitination have pivotal roles in the regulation of ABA signaling. In addition to the positive regulator sucrose non-fermenting-1 related protein kinase 2 (SnRK2), the relevance of the role of other protein kinases, such as CK2, has been recently highlighted. We have recently established that CK2 phosphorylates the maize ortholog of open stomata 1 OST1, ZmOST1, suggesting a role of CK2 phosphorylation in the control of ZmOST1 protein degradation (Vilela et al., 2015). CK2 is a pleiotropic enzyme involved in multiple developmental and stress-responsive pathways. This review summarizes recent advances that taken together suggest a prominent role of protein kinase CK2 in ABA signaling and related processes.
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16
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Bigeard J, Rayapuram N, Bonhomme L, Hirt H, Pflieger D. Proteomic and phosphoproteomic analyses of chromatin-associated proteins from Arabidopsis thaliana. Proteomics 2014; 14:2141-55. [PMID: 24889360 DOI: 10.1002/pmic.201400072] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/28/2014] [Accepted: 05/26/2014] [Indexed: 11/09/2022]
Abstract
The nucleus is the organelle where basically all DNA-related processes take place in eukaryotes, such as replication, transcription, and splicing as well as epigenetic regulation. The identification and description of the nuclear proteins is one of the requisites toward a comprehensive understanding of the biological functions accomplished in the nucleus. Many of the regulatory mechanisms of protein functions rely on their PTMs among which phosphorylation is probably one of the most important properties affecting enzymatic activity, interaction with other molecules, localization, or stability. So far, the nuclear and subnuclear proteome and phosphoproteome of the model plant Arabidopsis thaliana have been the subject of very few studies. In this work, we developed a purification protocol of Arabidopsis chromatin-associated proteins and performed proteomic and phosphoproteomic analyses identifying a total of 879 proteins of which 198 were phosphoproteins that were mainly involved in chromatin remodeling, transcriptional regulation, and RNA processing. From 230 precisely localized phosphorylation sites (phosphosites), 52 correspond to hitherto unidentified sites. This protocol and data thereby obtained should be a valuable resource for many domains of plant research.
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Affiliation(s)
- Jean Bigeard
- Unité de Recherche en Génomique Végétale (URGV), UMR INRA/CNRS/Université d'Evry Val d'Essonne/Saclay Plant Sciences, Evry, France
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17
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Mulekar JJ, Huq E. Expanding roles of protein kinase CK2 in regulating plant growth and development. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2883-93. [PMID: 24307718 DOI: 10.1093/jxb/ert401] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Protein kinase CK2 (formerly known as casein kinase II) is a ubiquitious Ser/Thr kinase present in all eukaryotes. The α (catalytic) and β (regulatory) subunits of CK2 exist both as a tetrameric holoenzyme and as monomers in eukaryotic cells. CK2 has been implicated in multiple developmental and stress-responsive pathways including light signalling and circadian clock in plants. Recent studies using CK2 knockout and dominant negative mutants in Arabidopsis have uncovered new roles for this enzyme. CK2 substrates that have been identified so far are primarily transcription factors or regulatory proteins. CK2-mediated phosphorylation of these factors often results in alteration of the protein function including changes in the DNA-binding affinity, dimerization, stability, protein-protein interactions, and subcellular localization. CK2 has evolved as an essential housekeeping kinase in plants that modifies protein function in a dynamic way. This review summarizes the current knowledge of the role of CK2 in plant development.
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Affiliation(s)
- Jidnyasa Jayant Mulekar
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Enamul Huq
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
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18
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Armengot L, Marquès-Bueno MM, Soria-Garcia A, Müller M, Munné-Bosch S, Martínez MC. Functional interplay between protein kinase CK2 and salicylic acid sustains PIN transcriptional expression and root development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 78:411-23. [PMID: 24547808 DOI: 10.1111/tpj.12481] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 01/27/2014] [Accepted: 02/10/2014] [Indexed: 05/12/2023]
Abstract
We have previously reported that CK2-defective Arabidopsis thaliana plants (CK2mut plants) were impaired severely in root development and auxin polar transport, and exhibited transcriptional misregulation of auxin-efflux transporters (Plant J., 67, 2011a, 169). In this work we show that CK2mut roots accumulate high levels of salicylic acid (SA) and that the gene that encodes isochorismate synthase (SID2) is overexpressed, strongly suggesting that CK2 activity is required for SA biosynthesis via the shikimate pathway. Moreover, SA activates transcription of CK2-encoding genes and, thus, SA and CK2 appear to be part of an autoregulatory feed-back loop to fine-tune each other's activities. We also show that exogenous SA and constitutive high SA levels in cpr mutants reproduce the CK2mut root phenotypes (decrease of root length and of number of lateral roots), whereas inhibition of CK2 activity in SA-defective and SA-signalling mutants lead to less severe phenotypes, suggesting that the CK2mut root phenotypes are SA-mediated effects. Moreover, exogenous SA mediates transcriptional repression of most of PIN-FORMED (PIN) genes, which is the opposite effect observed in CK2mut roots. These results prompted us to propose a model in which CK2 acts as a link between SA homeostasis and transcriptional regulation of auxin-efflux transporters. We also show that CK2 overexpression in Arabidopsis has neither impact on SA biosynthesis nor on auxin transport, but it improves the Arabidopsis root system. Thus, unlike the outcome in mammals, an excess of CK2 in plant cells does not produce neoplasia, but it might be advantageous for plant fitness.
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Affiliation(s)
- Laia Armengot
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra (Barcelona), Spain
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19
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Effect of salicylic acid on the attenuation of aluminum toxicity in Coffea arabica L. suspension cells: A possible protein phosphorylation signaling pathway. J Inorg Biochem 2013; 128:188-95. [PMID: 23953991 DOI: 10.1016/j.jinorgbio.2013.07.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 07/02/2013] [Accepted: 07/07/2013] [Indexed: 11/21/2022]
Abstract
The protective effect of salicylic acid (SA) on aluminum (Al) toxicity was studied in suspension cells of Coffea arabica L. The results showed that SA does not produce any effect on cell growth and that the growth inhibition produced by aluminum is restored during simultaneous treatment of the cells with Al and SA. In addition, the cells exposed to both compounds, Al and SA, showed evident morphological signals of recovery from the toxic state produced in the presence of Al. The cells treated with SA showed a lower accumulation of Al, which was linked to restoration from Al toxicity because the concentration of Al(3+) outside the cells, measured as the Al(3+)-morin complex, was not modified by the presence of SA. Additionally, the inhibition of phospholipase C by Al treatment was restored during the exposure of the cells to SA and Al. The involvement of protein phosphorylation in the protective effect of SA on Al-toxicity was suggested because staurosporine, a protein kinase inhibitor, reverted the stimulatory effect of the combination of Al and SA on protein kinase activity. These results suggest that SA attenuates aluminum toxicity by affecting a signaling pathway linked to protein phosphorylation.
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20
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Gatz C. From pioneers to team players: TGA transcription factors provide a molecular link between different stress pathways. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:151-9. [PMID: 23013435 DOI: 10.1094/mpmi-04-12-0078-ia] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The plant immune system encompasses an arsenal of defense genes that is activated upon recognition of a pathogen. Appropriate adjustment of gene expression is mediated by multiple interconnected signal transduction cascades that finally control the activity of transcription factors. These sequence-specific DNA-binding proteins act at the interface between the DNA and the regulatory protein network. In 1989, tobacco TGA1a was cloned as the first plant transcription factor. Since then, multiple studies have shown that members of the TGA family play important roles in defense responses against biotrophic and necrotrophic pathogens and against chemical stress. Here, we review 22 years of research on TGA factors which have yielded both consistent and conflicting results.
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Affiliation(s)
- Christiane Gatz
- Georg-August-University of Göttingen (GAU), Albrecht-von-Haller-Institute for Plant Sciences, Julia-Lermontowa-Weg 3, 37077 Göttingen, Germany.
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21
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Tsai YC, Koo Y, Delk NA, Gehl B, Braam J. Calmodulin-related CML24 interacts with ATG4b and affects autophagy progression in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:325-35. [PMID: 23039100 DOI: 10.1111/tpj.12043] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 09/20/2012] [Accepted: 10/02/2012] [Indexed: 05/10/2023]
Abstract
Plants encounter environmental stress challenges that are distinct from those of other eukaryotes because of their relative immobility. Therefore, plants may have evolved distinct regulatory mechanisms for conserved cellular functions. Plants, like other eukaryotes, share aspects of both calcium- and calmodulin-based cellular signaling and the autophagic process of cellular renewal. Here, we report a novel function for an Arabidopsis calmodulin-related protein, CML24, and insight into ATG4-regulated autophagy. CML24 interacts with ATG4b in yeast two-hybrid, in vitro pull-down and transient tobacco cell transformation assays. Mutants with missense mutations in CML24 have aberrant ATG4 activity patterns in in vitro extract assays, altered ATG8 accumulation levels, an altered pattern of GFP-ATG8-decorated cellular structures, and altered recovery from darkness-induced starvation. Together, these results support the conclusion that CML24 affects autophagy progression through interactions with ATG4.
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Affiliation(s)
- Yu-Chang Tsai
- Biochemistry and Cell Biology, Rice University, Houston, TX, 77005-1892, USA
| | - Yeonjong Koo
- Biochemistry and Cell Biology, Rice University, Houston, TX, 77005-1892, USA
| | - Nikkí A Delk
- Biochemistry and Cell Biology, Rice University, Houston, TX, 77005-1892, USA
| | - Bernadette Gehl
- Biochemistry and Cell Biology, Rice University, Houston, TX, 77005-1892, USA
| | - Janet Braam
- Biochemistry and Cell Biology, Rice University, Houston, TX, 77005-1892, USA
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22
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Mulekar JJ, Bu Q, Chen F, Huq E. Casein kinase II α subunits affect multiple developmental and stress-responsive pathways in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 69:343-54. [PMID: 21950772 DOI: 10.1111/j.1365-313x.2011.04794.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Casein kinase II (formerly known as CK2), a ubiquitous Ser/Thr kinase, plays critical roles in all higher organisms including plants. The CK2 holoenzyme consists of two catalytic α subunits and two regulatory β subunits. The Arabidopsis genome has four α subunit and four β subunit genes, and members of both the α and β subunit families have been shown to be localized in the cytoplasm, nucleus and also in chloroplasts. However, the biological roles of CK2 subunits have not been fully characterized yet. Here we identified T-DNA insertion mutants in three α subunit genes (α1, α2 and α3) and made double and triple mutants. The CK2 α1α2α3 triple mutants displayed reduced CK2 activity compared with wild-type seedlings. Phenotypic characterization showed that CK2 α1α2α3 triple mutants are late flowering under both long- and short-day conditions. Genes encoding floral integrators are differentially regulated in the triple mutant compared with the wild-type plants. CK2 α1α2α3 triple mutants also displayed reduced hypocotyl growth, smaller cotyledon size and a reduced number of lateral roots compared with wild-type seedlings under light. Abscisic acid-induced blockage of seed germination and cotyledon greening is reduced in CK2 α subunit mutants in an additive manner. Moreover, CK2 α subunit mutants are also hyposensitive to a NaCl-induced blockage of seed germination. Taken together, these data suggest that CK2 α subunits affect diverse developmental and stress responsive pathways in Arabidopsis.
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Affiliation(s)
- Jidnyasa Jayant Mulekar
- Section of Molecular Cell and Developmental Biology and The Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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23
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About the role of CK2 in plant signal transduction. Mol Cell Biochem 2011; 356:233-40. [DOI: 10.1007/s11010-011-0970-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 06/24/2011] [Indexed: 12/24/2022]
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24
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The p23 co-chaperone protein is a novel substrate of CK2 in Arabidopsis. Mol Cell Biochem 2011; 356:245-54. [DOI: 10.1007/s11010-011-0969-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 06/24/2011] [Indexed: 11/26/2022]
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25
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Marquès-Bueno MM, Moreno-Romero J, Abas L, De Michele R, Martínez MC. A dominant negative mutant of protein kinase CK2 exhibits altered auxin responses in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 67:169-80. [PMID: 21435053 DOI: 10.1111/j.1365-313x.2011.04585.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Protein kinase CK2 is a pleiotropic Ser/Thr kinase, evolutionary conserved in eukaryotes. Studies performed in different organisms, from yeast to humans, have highlighted the importance of CK2 in cell growth and cell-cycle control. However, the signalling pathways in which CK2 is involved have not been fully identified. In plants, the phytohormone auxin is a major regulator of cell growth. Recent discoveries have demonstrated that differential distribution of within auxin plant tissues is essential for developmental processes, and that this distribution is dependent on polar auxin transport. We report here that a dominant-negative mutant of CK2 (CK2mut) in Arabidopsis thaliana shows phenotypic traits that are typically linked to alterations in auxin-dependent processes. However, CK2mut plants exhibit normal responses to exogenous indole-3-acetic acid (IAA) indicating that they are not affected in the perception of the hormone but upstream in the pathway. We demonstrate that mutant plants are not deficient in IAA but are impaired in its transport. Using genetic and pharmacological tools we show that CK2 activity depletion hinders correct formation of auxin gradients and leads to widespread changes in the expression of auxin-related genes. In particular, members of the auxin efflux carrier family (PINs), and the protein kinase PINOID, both key regulators of auxin fluxes, were misexpressed. PIN4 and PIN7 were also found mislocalized, with accumulation in endosomal bodies. We propose that CK2 functions in the regulation of auxin-signalling pathways, particularly in auxin transport.
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Affiliation(s)
- Maria Mar Marquès-Bueno
- Departament de Bioquímica i Biologia Molecular, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain
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26
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Boyle P, Després C. Dual-function transcription factors and their entourage: unique and unifying themes governing two pathogenesis-related genes. PLANT SIGNALING & BEHAVIOR 2010; 5:629-34. [PMID: 20383056 PMCID: PMC3001550 DOI: 10.4161/psb.5.6.11570] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Much of what we, as plant molecular biologists studying gene regulation, know comes from paradigms characterized or developed in mammalian systems. Although plants, animals, and fungi have been diverging for a very long time, a great deal of the machineries and components discovered in yeast and mammals seem to have been maintained in plants. Nevertheless, despite this apparent conservation, evolutionary pressures on the mechanisms of gene regulation are likely to be different between these kingdoms, given their different environmental constraints. As such, it is imperative for plant molecular biologists to develop their own paradigms, even on seemingly conserved systems. It is with this intent that we compare and contrast the regulation of two pathogenesis-related genes, the arabidopsis PR-1 and potato PR-10a genes. The transcription factors regulating these genes present prime paradigms for the study of plant signal- and context-dependent dual-function transcription factors.
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Affiliation(s)
- Patrick Boyle
- Department of Biological Sciences, Brock University, St Catharines, ON, Canada
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27
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Lebska M, Szczegielniak J, Dobrowolska G, Cozza G, Moro S, Muszyńska G. A novel splicing variant encoding putative catalytic alpha subunit of maize protein kinase CK2. PHYSIOLOGIA PLANTARUM 2009; 136:251-263. [PMID: 19470094 DOI: 10.1111/j.1399-3054.2009.01238.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A cDNA highly homologous to the known catalytic alpha subunit of protein kinase CK2 was cloned from maize (Zea mays). It was designated ZmCK2alpha-4 (accession no. AAF76187). Sequence analysis shows that ZmCK2alpha-4 and the previously identified ZmCK2alpha-1 (accession no. X61387) are transcribed from the same gene, ZmPKCK2AL (accession no. Y11649), but at different levels in various maize organs and at different stages of development. The cDNA encoding ZmCK2alpha-4 has three potential translation initiation sites. The three putative variants of ZmCK2alpha-4 were expressed in Escherichia coli as GST-fusion proteins and purified from bacterial extracts. In contrast to the previously characterized ZmCK2alphas, the obtained GST:ZmCK2alpha-4 proteins were catalytically inactive as monomers or in the presence of equimolar amounts of the human CK2beta. However, GST:ZmCK2alpha-4 did phosphorylate casein in the presence of a large excess of the beta subunit. The activity of ZmCK2alpha-4 toward casein could also be stimulated by increasing ATP concentration. Modeling studies have shown that there is no interaction between the N-terminal segment of ZmCK2alpha-4 and the activation loop responsible for constitutive catalytic activity of CK2alpha. Preliminary results suggest that ZmCK2alpha-4 may function as a negative regulator of other CK2s, and at certain circumstances as a holoenzyme which catalytic activity is stimulated by specific regulatory subunit(s).
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Affiliation(s)
- Maja Lebska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland
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Moreno-Romero J, Espunya MC, Platara M, Ariño J, Martínez MC. A role for protein kinase CK2 in plant development: evidence obtained using a dominant-negative mutant. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 55:118-30. [PMID: 18363781 DOI: 10.1111/j.1365-313x.2008.03494.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Protein kinase CK2 is an evolutionary conserved Ser/Thr phosphotransferase composed of two distinct subunits, alpha (catalytic) and beta (regulatory), that combine to form a tetrameric complex. Plant genomes contain multiple genes for each subunit, the expression of which gives rise to different active holoenzymes. In order to study the effects of loss of function of CK2 on plant development, we have undertaken a dominant-negative mutant approach. We generated an inactive catalytic subunit by site-directed mutagenesis of an essential lysine residue. The mutated open reading frame was cloned downstream of an inducible promoter, and stably transformed Arabidopsis thaliana plants and tobacco BY2 cells were isolated. Continuous expression of the CK2 kinase-inactive subunit did not prevent seed germination, but seedlings exhibited a strong phenotype, affecting chloroplast development, cotyledon expansion, and root and shoot growth. Prolonged induction of the transgene was lethal. Moreover, dark-germinated seedlings exhibited an apparent de-etiolated phenotype that was not caused by disruption of the light-signalling pathways. Short-term induction of the CK2 kinase-inactive subunit allowed plant survival, but root growth and lateral root formation were significantly affected. The expression pattern of CYCB1;1::GFP in the root meristems of mutant plants demonstrated an important decrease of mitotic activity, and expression of the CK2 kinase-inactive subunit in stably transformed BY2 cells provoked perturbation of the G1/S and G2 phases of the cell cycle. Our results are consistent with a model in which CK2 plays a key role in cell division and cell expansion, with compelling effects on Arabidopsis development.
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Affiliation(s)
- Jordi Moreno-Romero
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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29
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Kang HG, Kuhl JC, Kachroo P, Klessig DF. CRT1, an Arabidopsis ATPase that interacts with diverse resistance proteins and modulates disease resistance to turnip crinkle virus. Cell Host Microbe 2008; 3:48-57. [PMID: 18191794 DOI: 10.1016/j.chom.2007.11.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2007] [Revised: 09/12/2007] [Accepted: 11/26/2007] [Indexed: 01/30/2023]
Abstract
Plant immunity frequently involves the recognition of pathogen-encoded avirulence (avr) factors by their corresponding plant resistance (R) proteins. This triggers the hypersensitive response (HR) where necrotic lesions formed at the site(s) of infection help restrict pathogen spread. HRT is an Arabidopsis R protein required for resistance to turnip crinkle virus (TCV). In a genetic screen for mutants compromised in the recognition of TCV's avr factor, we identified crt1 (compromised recognition of TCV), a mutant that prematurely terminates an ATPase protein. Following TCV infection, crt1 developed a spreading HR and failed to control viral replication and spread. crt1 also suppressed HR-like cell death induced by ssi4, a constitutively active R protein, and by Pseudomonas syringae carrying avrRpt2. Furthermore, CRT1 interacts with HRT, SSI4, and two other R proteins, RPS2 and Rx. These data identify CRT1 as an important mediator of defense signaling triggered by distinct classes of R proteins.
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Affiliation(s)
- Hong-Gu Kang
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA
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30
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Kesarwani M, Yoo J, Dong X. Genetic interactions of TGA transcription factors in the regulation of pathogenesis-related genes and disease resistance in Arabidopsis. PLANT PHYSIOLOGY 2007; 144:336-46. [PMID: 17369431 PMCID: PMC1913812 DOI: 10.1104/pp.106.095299] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
TGA transcription factors are implicated as regulators of pathogenesis-related (PR) genes because of their physical interaction with the known positive regulator, nonexpresser of PR gene1 (NPR1). A triple-knockout mutant tga2-1 tga5-1 tga6-1 was shown previously to be defective in the induction of PR genes and systemic acquired resistance, confirming their role in disease resistance. However, the contributions of individual TGA factors have been difficult to discern because of functional redundancy among these factors, as well as possible dual functions for some single factors. In this study, we characterized six TGA factors by reverse genetics. We show that TGA3 is required for both basal and 2,6-dichloroisonicotinic acid-induced transcription of PR genes. The tga3-1 mutants were found to be defective in basal pathogen resistance, whereas induced resistance was unaffected. TGA1 and TGA4 play partially redundant roles in regulation of basal resistance, having only moderate effects on PR gene expression. Additionally, an activation-tagged mutant of TGA6 was able to increase basal as well as induced expression of PR1, demonstrating a positive role for TGA6 on PR gene expression. In contrast, TGA2 has repressor activity on PR gene expression even though it can act as a positive regulator in the tga5-1 tga6-1 null mutant background. Finally, we examined the genetic interaction between tga2-2 and suppressor of npr1 inducible1 (sni1-1). TGA2's repressor activity overlaps with SNI1 because the tga2-2 sni1-1 double mutant shows a synergistic effect on PR gene expression.
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Affiliation(s)
- Meenu Kesarwani
- Department of Biology, Duke University, Durham, NC 27708, USA.
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31
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Ndamukong I, Abdallat AA, Thurow C, Fode B, Zander M, Weigel R, Gatz C. SA-inducible Arabidopsis glutaredoxin interacts with TGA factors and suppresses JA-responsive PDF1.2 transcription. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2007; 50:128-39. [PMID: 17397508 DOI: 10.1111/j.1365-313x.2007.03039.x] [Citation(s) in RCA: 264] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Salicylic acid (SA) is a plant signaling molecule that mediates the induction of defense responses upon attack by a variety of pathogens. Moreover, it antagonizes gene induction by the stress signaling molecule jasmonic acid (JA). Several SA-responsive genes are regulated by basic/leucine zipper-type transcription factors of the TGA family. TGA factors interact with NPR1, a central regulator of many SA-induced defense responses including SA/JA antagonism. In order to identify further regulatory proteins of SA-dependent signaling pathways, a yeast protein interaction screen with tobacco TGA2.2 as bait and an Arabidopsis thaliana cDNA prey library was performed and led to the identification of a member of the glutaredoxin family (GRX480, encoded by At1g28480). Glutaredoxins are candidates for mediating redox regulation of proteins because of their capacity to catalyze disulfide transitions. This agrees with previous findings that the redox state of both TGA1 and NPR1 changes under inducing conditions. Transgenic Arabidopsis plants ectopically expressing GRX480 show near wild-type expression of standard marker genes for SA- and xenobiotic-inducible responses. In contrast, transcription of the JA-dependent defensin gene PDF1.2 was antagonized by transgenic GRX480. This, together with the observation that GRX480 transcription is SA-inducible and requires NPR1, suggests a role of GRX480 in SA/JA cross-talk. Suppression of PDF1.2 by GRX480 depends on the presence of TGA factors, indicating that the GRX480/TGA interaction is effective in planta.
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Affiliation(s)
- Ivan Ndamukong
- Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Georg-August-Universität Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany
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32
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Huang HE, Ger MJ, Chen CY, Pandey AK, Yip MK, Chou HW, Feng TY. Disease resistance to bacterial pathogens affected by the amount of ferredoxin-I protein in plants. MOLECULAR PLANT PATHOLOGY 2007; 8:129-37. [PMID: 20507485 DOI: 10.1111/j.1364-3703.2006.00378.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
SUMMARY Ferredoxin-I (Fd-I) is a fundamental protein that is involved in several metabolic pathways. The amount of Fd-I found in plants is generally regulated by environmental stress, including biotic and abiotic events. In this study, the correlation between quantity of Fd-I and plant disease resistance was investigated. Fd-I levels were increased by inoculation with Pseudomonas syringae pv. syringae but were reduced by Erwinia carotovora ssp. carotovora. Transgenic tobacco over-expressing Fd-I with the sense sweet pepper Fd-I gene (pflp) was resistant to E. carotovora ssp. carotovora and the saprophytic bacterium P. fluorescens. By contrast, transgenic tobacco with reduced total Fd-I and the antisense pflp gene was susceptible to E. carotovora ssp. carotovora and P. fluorescens. Both of these transgenic tobaccos were resistant to P. syringae pv. syringae. By contrast, the mutated E. carotovora ssp. carotovora, with a defective harpin protein, was able to invade the sense-pflp transgenic tobacco as well as the non-transgenic tobacco. An in vitro kinase assay revealed that harpin could activate unidentified kinases to phosphorylate PFLP. These results demonstrate that Fd-I plays an important role in the disease defence mechanism.
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Affiliation(s)
- Hsiang-En Huang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 115, Taiwan
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33
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Rochon A, Boyle P, Wignes T, Fobert PR, Després C. The coactivator function of Arabidopsis NPR1 requires the core of its BTB/POZ domain and the oxidation of C-terminal cysteines. THE PLANT CELL 2006; 18:3670-85. [PMID: 17172357 PMCID: PMC1785396 DOI: 10.1105/tpc.106.046953] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 (NPR1) regulates systemic acquired resistance (SAR) in Arabidopsis thaliana, and current models propose that after treatment with salicylic acid (SA), Cys-82 and Cys-216 of NPR1 are reduced, leading to nuclear import. The interaction of nucleus-localized NPR1 with TGA transcription factors results in the activation of defense genes, including the SAR marker PATHOGENESIS-RELATED-1 (PR-1), and the deployment of SAR. Little is known about how TGA factors or NPR1 regulate transcription or whether a TGA-NPR1 complex forms on DNA. We show that TGA2 and NPR1 are recruited to PR-1 independently of each other and of SA treatment. Consistent with the result that a triple knockout in TGA2/5/6 derepresses PR-1, in vivo plant transcription assays revealed that TGA2 is not an autonomous transcription activator but is a transcriptional repressor in both untreated and SA-treated cells. However, after stimulation with SA, TGA2 is incorporated into a transactivating complex with NPR1, forming an enhanceosome that requires the core of the NPR1 BTB/POZ domain (residues 80 to 91) and the oxidation of NPR1 Cys-521 and Cys-529. These Cys residues are found in a new type of transactivation domain that we term Cys-oxidized. These data further our understanding of the mechanism by which TGA2 and NPR1 activate Arabidopsis PR-1.
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Affiliation(s)
- Amanda Rochon
- Department of Biological Sciences, Brock University, St. Catharines, Ontario, Canada L2S 3A1
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34
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Salinas P, Fuentes D, Vidal E, Jordana X, Echeverria M, Holuigue L. An extensive survey of CK2 alpha and beta subunits in Arabidopsis: multiple isoforms exhibit differential subcellular localization. PLANT & CELL PHYSIOLOGY 2006; 47:1295-308. [PMID: 16926165 DOI: 10.1093/pcp/pcj100] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Casein kinase 2 (CK2) is a ubiquitous enzyme essential for the viability of eukaryotic cells. In the present work we analyzed the Arabidopsis thaliana genome in a search for the genes coding for all CK2 alpha and beta subunits. We found four alpha subunit and four beta subunit genes. Expression analysis showed that all CK2 subunit genes are expressed in inflorescences, stems, leaves and roots. The level of expression of these genes is very similar, except for the one that codes for an alpha subunit harboring a putative chloroplastic destination peptide (alphacp), which shows a slightly higher expression level in all tissues. Using transgenic plants and agroinfiltration, we have also characterized the subcellular localization of all proteins encoded by CK2 genes. Our results show that all alpha subunits are localized in the nucleus, with the exception of alphacp, which is only found in the chloroplasts. On the other hand, beta subunits have a more diverse distribution, with some of them localizing both to the nucleus and to the cytosol, while others are exclusively located in one of these compartments. Remarkably, no CK2beta subunit was found in the chloroplasts. Finally, by directly measuring its activity, we have demonstrated that purified Arabidopsis chloroplasts have active CK2 that can be regulated by external addition of CK2beta. This study represents a complete survey of the CK2 gene family in Arabidopsis and the first step for future studies on CK2 cellular function in this species.
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Affiliation(s)
- Paula Salinas
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, PO Box 114-D, Santiago, Chile
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35
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Foley RC, Sappl PG, Perl-Treves R, Millar AH, Singh KB. Desensitization of GSTF8 induction by a prior chemical treatment is long lasting and operates in a tissue-dependent manner. PLANT PHYSIOLOGY 2006; 142:245-53. [PMID: 16829588 PMCID: PMC1557611 DOI: 10.1104/pp.106.079509] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The Arabidopsis (Arabidopsis thaliana) GSTF8 gene is a member of the glutathione S-transferase (GST) family whose expression is induced by defense signals, certain chemical stresses, and some pathogens. Here, we have used transgenic plants and an in vivo imaging system to demonstrate that GSTF8 expression is subject to a distinct desensitization phenomenon because prior chemical treatment significantly reduces reactivation of the GSTF8 promoter by hydrogen peroxide, auxin, and salicylic acid. A GSTF8 null line had similar desensitization properties to wild type, demonstrating that GSTF8 protein levels are not responsible for desensitization. The resulting refractory period is unusually long lasting, with full recovery taking 4 d. Expression of the GSTF8 promoter following a second treatment occurred predominantly in newly formed tissue at the root tip, suggesting that desensitization is lost upon cell division. Expression of the endogenous GSTF8 gene and another GST gene, GSTF6, is also desensitized following treatment with hydrogen peroxide. The desensitization phenomenon can be activated by a very low concentration of inducer that is not sufficient to activate the GSTF8 promoter. These results demonstrate that activation of the GSTF8 promoter is not essential for eliciting desensitization. A key promoter sequence within the GSTF8 gene, the ocs element, is also affected by desensitization. Treatment with a phosphatase inhibitor prevents desensitization of GSTF8 expression and ocs element activity, suggesting that dephosphorylation of one or more proteins is required for desensitization to occur.
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Affiliation(s)
- Rhonda C Foley
- Commonwealth Scientific and Industrial Research Organization Plant Industry, Centre for Environmental and Life Sciences, Wembley, Western Australia 6913, Australia
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36
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Menke FLH, Kang HG, Chen Z, Park JM, Kumar D, Klessig DF. Tobacco transcription factor WRKY1 is phosphorylated by the MAP kinase SIPK and mediates HR-like cell death in tobacco. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2005; 18:1027-34. [PMID: 16255241 DOI: 10.1094/mpmi-18-1027] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The salicylic acid-induced protein kinase (SIPK) of tobacco, which is a mitogen-activated protein kinase (MAPK), is activated by various biotic and abiotic treatments. Overexpression of SIPK has been shown to trigger cell death. In this study, a targeted yeast two-hybrid approach identified the tobacco transcription factor WRKY1 as a potential substrate. SIPK phosphorylated WRKY1, which resulted in enhanced DNA-binding activity of WRKY1 to its cognate binding site, a W box sequence from the tobacco chitinase gene CHN50. SIPK-mediated enhancement of WRKY1 DNA-binding activity was inhibited by staurosporine, a general kinase inhibitor. Co-expression of SIPK and WRKY1 in Nicotiana benthamiana led to more rapid cell death than expression of SIPK alone, suggesting that WRKY1 is involved in the formation of hypersensitive response-like cell death and may be a component of the signaling cascade downstream of SIPK.
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Affiliation(s)
- Frank L H Menke
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA
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