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Zeng H, Zhu Q, Yuan P, Yan Y, Yi K, Du L. Calmodulin and calmodulin-like protein-mediated plant responses to biotic stresses. PLANT, CELL & ENVIRONMENT 2023; 46:3680-3703. [PMID: 37575022 DOI: 10.1111/pce.14686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/10/2023] [Accepted: 08/01/2023] [Indexed: 08/15/2023]
Abstract
Plants have evolved a set of finely regulated mechanisms to respond to various biotic stresses. Transient changes in intracellular calcium (Ca2+ ) concentration have been well documented to act as cellular signals in coupling environmental stimuli to appropriate physiological responses with astonishing accuracy and specificity in plants. Calmodulins (CaMs) and calmodulin-like proteins (CMLs) are extensively characterized as important classes of Ca2+ sensors. The spatial-temporal coordination between Ca2+ transients, CaMs/CMLs and their target proteins is critical for plant responses to environmental stresses. Ca2+ -loaded CaMs/CMLs interact with and regulate a broad spectrum of target proteins, such as ion transporters (including channels, pumps, and antiporters), transcription factors, protein kinases, protein phosphatases, metabolic enzymes and proteins with unknown biological functions. This review focuses on mechanisms underlying how CaMs/CMLs are involved in the regulation of plant responses to diverse biotic stresses including pathogen infections and herbivore attacks. Recent discoveries of crucial functions of CaMs/CMLs and their target proteins in biotic stress resistance revealed through physiological, molecular, biochemical, and genetic analyses have been described, and intriguing insights into the CaM/CML-mediated regulatory network are proposed. Perspectives for future directions in understanding CaM/CML-mediated signalling pathways in plant responses to biotic stresses are discussed. The application of accumulated knowledge of CaM/CML-mediated signalling in biotic stress responses into crop cultivation would improve crop resistance to various biotic stresses and safeguard our food production in the future.
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Affiliation(s)
- Houqing Zeng
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Qiuqing Zhu
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Peiguo Yuan
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, Texas, USA
| | - Yan Yan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, USA
| | - Keke Yi
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Liqun Du
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
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Pedretti M, Favretto F, Troilo F, Giovannoni M, Conter C, Mattei B, Dominici P, Travaglini-Allocatelli C, Di Matteo A, Astegno A. Role of myristoylation in modulating PCaP1 interaction with calmodulin. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 203:108003. [PMID: 37717348 DOI: 10.1016/j.plaphy.2023.108003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 08/09/2023] [Accepted: 09/04/2023] [Indexed: 09/19/2023]
Abstract
Plasma membrane-associated Cation-binding Protein 1 (PCaP1) belongs to the plant-unique DREPP protein family with largely unknown biological functions but ascertained roles in plant development and calcium (Ca2+) signaling. PCaP1 is anchored to the plasma membrane via N-myristoylation and a polybasic cluster, and its N-terminal region can bind Ca2+/calmodulin (CaM). However, the molecular determinants of PCaP1-Ca2+-CaM interaction and the functional impact of myristoylation in the complex formation and Ca2+ sensitivity of CaM remained to be elucidated. Herein, we investigated the direct interaction between Arabidopsis PCaP1 (AtPCaP1) and CaM1 (AtCaM1) using both myristoylated and non-myristoylated peptides corresponding to the N-terminal region of AtPCaP1. ITC analysis showed that AtCaM1 forms a high affinity 1:1 complex with AtPCaP1 peptides and the interaction is strictly Ca2+-dependent. Spectroscopic and kinetic Ca2+ binding studies showed that the myristoylated peptide dramatically increased the Ca2+-binding affinity of AtCaM1 and slowed the Ca2+ dissociation rates from both the C- and N-lobes, thus suggesting that the myristoylation modulates the mechanism of AtPCaP1 recognition by AtCaM1. Furthermore, NMR and CD spectroscopy revealed that the structure of both the N- and C-lobes of Ca2+-AtCaM1 changes markedly in the presence of the myristoylated AtPCaP1 peptide, which assumes a helical structure in the final complex. Overall, our results indicate that AtPCaP1 biological function is strictly related to the presence of multiple ligands, i.e., the myristoyl moiety, Ca2+ ions and AtCaM1 and only a full characterization of their equilibria will allow for a complete molecular understanding of the putative role of PCaP1 as signal protein.
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Affiliation(s)
- Marco Pedretti
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Filippo Favretto
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Francesca Troilo
- CNR Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Moira Giovannoni
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | - Carolina Conter
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Benedetta Mattei
- Department of Life, Health and Environmental Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | - Paola Dominici
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | | | - Adele Di Matteo
- CNR Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185, Rome, Italy.
| | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
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Wang H, Feng M, Zhong X, Yu Q, Que Y, Xu L, Guo J. Identification of Saccharum CaM gene family and function characterization of ScCaM1 during cold and oxidant exposure in Pichia pastoris. Genes Genomics 2023; 45:103-122. [PMID: 35608775 DOI: 10.1007/s13258-022-01263-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Accepted: 05/03/2022] [Indexed: 01/11/2023]
Abstract
BACKGROUND Calmodulin (CaM) plays an essential role in binding calcium ions and mediating the interpretation of Ca2+ signals in plants under various stresses. However, the evolutionary relationship of CaM family proteins in Saccharum has not been elucidated. OBJECTIVE To deduce and explore the evolution and function of Saccharum CaM family. METHODS A total of 104 typical CaMs were obtained from Saccharum spontaneum and other 18 plant species. The molecular characteristics and evolution of those CaM proteins were analyzed. A typical CaM gene, ScCaM1, was subsequently cloned from sugarcane (Saccharum spp. hybrid). Its expression patterns in different tissues and under various abiotic stresses were assessed by quantitative real-time PCR. Then the green fluorescent protein was used to determine the subcellular localization of ScCaM1. Finally, the function of ScCaM1 was evaluated via heterologous yeast expression systems. RESULTS Three typical CaM members (SsCaM1, SsCaM2, and SsCaM3) were identified from the S. spontaneum genome database. CaMs were originated from the two last common ancestors before the origin of angiosperms. The number of CaM family members did not correlate to the genome size but correlated with allopolyploidization events. The ScCaM1 was more highly expressed in buds and roots than in other tissues. The expression patterns of ScCaM1 suggested that it was involved in responses to various abiotic stresses in sugarcane via different hormonal signaling pathways. Noteworthily, its expression levels appeared relatively stable during the cold exposure in the cold-tolerant variety but significantly suppressed in the cold-susceptible variety. Moreover, the recombinant yeast (Pichia pastoris) overexpressing ScCaM1 grew better than the wild-type yeast strain under cold and oxidative stresses. It was revealed that the ScCaM1 played a positive role in reactive oxygen species scavenging and conferred enhanced cold and oxidative stress tolerance to cells. CONCLUSION This study provided comprehensive information on the CaM gene family in Saccharum and would facilitate further investigation of their functional characterization.
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Affiliation(s)
- Hengbo Wang
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Meichang Feng
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Xiaoqiang Zhong
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Qing Yu
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Youxiong Que
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Liping Xu
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Jinlong Guo
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
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Troilo F, Pedretti M, Travaglini-Allocatelli C, Astegno A, Di Matteo A. Rapid kinetics of calcium dissociation from plant calmodulin and calmodulin-like proteins and effect of target peptides. Biochem Biophys Res Commun 2022; 590:103-108. [PMID: 34974297 DOI: 10.1016/j.bbrc.2021.12.077] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 12/21/2021] [Indexed: 11/02/2022]
Abstract
Calcium (Ca2+) signaling represents a universal information code in plants, playing crucial roles spanning developmental processes to stress responses. Ca2+ signals are decoded into defined plant adaptive responses by different Ca2+ sensing proteins, including calmodulin (CaM) and calmodulin-like (CML) proteins. Although major advances have been achieved in describing how these Ca2+ decoding proteins interact and regulate downstream target effectors, the molecular details of these processes remain largely unknown. Herein, the kinetics of Ca2+ dissociation from a conserved CaM and two CML isoforms from A. thaliana has been studied by fluorescence stopped-flow spectroscopy. Kinetic data were obtained for the isolated Ca2+-bound proteins as well as for the proteins complexed with different target peptides. Moreover, the lobe specific interactions between the Ca2+ sensing proteins and their targets were characterized by using a panel of protein mutants deficient in Ca2+ binding at the N-lobe or C-lobe. Results were analyzed and discussed in the context of the Ca2+-decoding and Ca2+-controlled target binding mechanisms in plants.
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Affiliation(s)
- Francesca Troilo
- CNR Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Marco Pedretti
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | | | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy.
| | - Adele Di Matteo
- CNR Institute of Molecular Biology and Pathology, P.le Aldo Moro 5, 00185, Rome, Italy.
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Sun B, Fang X, Johnson C, Hauck G, Kou Y, Davis JP, Kekenes-Huskey PM. Non-Canonical Interaction between Calmodulin and Calcineurin Contributes to the Differential Regulation of Plant-Derived Calmodulins on Calcineurin. J Chem Inf Model 2021; 61:5223-5233. [PMID: 34615359 PMCID: PMC8867402 DOI: 10.1021/acs.jcim.1c00873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Calmodulin (CaM) serves as an important Ca2+ signaling hub that regulates many protein signaling pathways. Recently, it was demonstrated that plant CaM homologues can regulate mammalian targets, often in a manner that opposes the impact of the mammalian CaM (mCaM). However, the molecular basis of how CaM homologue mutations differentially impact target activation is unclear. To understand these mechanisms, we examined two CaM isoforms found in soybean plants that differentially regulate a mammalian target, calcineurin (CaN). These CaM isoforms, sCaM-1 and sCaM-4, share >90 and ∼78% identity with the mCaM, respectively, and activate CaN with comparable or reduced activity relative to mCaM. We used molecular dynamics (MD) simulations and fluorometric assays of CaN-dependent dephosphorylation of MUF-P to probe whether calcium and protein-protein binding interactions are altered by plant CaMs relative to mCaM as a basis for differential CaN regulation. In the presence of CaN, we found that the two sCaMs' Ca2+ binding properties, such as their predicted coordination of Ca2+ and experimentally measured EC50 [Ca2+] values are comparable to mCaM. Furthermore, the binding of CaM to the CaM binding region (CaMBR) in CaN is comparable among the three CaMs, as evidenced by MD-predicted binding energies and experimentally measured EC50 [CaM] values. However, mCaM and sCaM-1 exhibited binding with a secondary region of CaN's regulatory domain that is weakened for sCaM-4. We speculate that this secondary interaction affects the turnover rate (kcat) of CaN based on our modeling of enzyme activity, which is consistent with our experimental data. Together, our data describe how plant-derived CaM variants alter CaN activity through enlisting interactions other than those directly influencing Ca2+ binding and canonical CaMBR binding, which may additionally play a role in the differential regulation of other mammalian targets.
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Affiliation(s)
- Bin Sun
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, USA 60153
| | - Xuan Fang
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, USA 60153
| | - Christopher Johnson
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA 43210
- Department of Chemistry, Mississippi State University Starkville MS, 39759
| | - Garrett Hauck
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA 43210
| | - Yongjun Kou
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA 43210
| | - Jonathan P. Davis
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA 43210
| | - Peter M. Kekenes-Huskey
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, USA 60153
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Yaduvanshi S, Ero R, Kumar V. The mechanism of complex formation between calmodulin and voltage gated calcium channels revealed by molecular dynamics. PLoS One 2021; 16:e0258112. [PMID: 34610038 PMCID: PMC8491939 DOI: 10.1371/journal.pone.0258112] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 09/18/2021] [Indexed: 11/18/2022] Open
Abstract
Calmodulin, a ubiquitous eukaryotic calcium sensor responsible for the regulation of many fundamental cellular processes, is a highly flexible protein and exhibits an unusually wide range of conformations. Furthermore, CaM is known to interact with more than 300 cellular targets. Molecular dynamics (MD) simulation trajectories suggest that EF-hand loops show different magnitudes of flexibility. Therefore, the four EF-hand motifs have different affinities for Ca2+ ions, which enables CaM to function on wide range of Ca2+ ion concentrations. EF-hand loops are 2-3 times more flexible in apo CaM whereas least flexible in Ca2+/CaM-IQ motif complexes. We report a unique intermediate conformation of Ca2+/CaM while transitioning from extended to compact form. We also report the complex formation process between Ca2+/CaM and IQ CaM-binding motifs. Our results showed how IQ motif recognise its binding site on the CaM and how CaM transforms from extended to compact form upon binding to IQ motif.
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Affiliation(s)
- Shivani Yaduvanshi
- Amity Institute of Molecular Medicine and Stem Cell Research (AIMMSCR), Amity University Noida, Noida, Uttar Pradesh, India
| | - Rya Ero
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Veerendra Kumar
- Amity Institute of Molecular Medicine and Stem Cell Research (AIMMSCR), Amity University Noida, Noida, Uttar Pradesh, India
- * E-mail:
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Raina M, Kumar A, Yadav N, Kumari S, Yusuf MA, Mustafiz A, Kumar D. StCaM2, a calcium binding protein, alleviates negative effects of salinity and drought stress in tobacco. PLANT MOLECULAR BIOLOGY 2021; 106:85-108. [PMID: 33629224 DOI: 10.1007/s11103-021-01131-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 02/09/2021] [Indexed: 05/20/2023]
Abstract
KEY MESSAGE Overexpression of StCaM2 in tobacco promotes plant growth and confers increased salinity and drought tolerance by enhancing the photosynthetic efficiency, ROS scavenging, and recovery from membrane injury. Calmodulins (CaMs) are important Ca2+ sensors that interact with effector proteins and drive a network of signal transduction pathways involved in regulating the growth and developmental pattern of plants under stress. Herein, using in silico analysis, we identified 17 CaM isoforms (StCaM) in potato. Expression profiling revealed different temporal and spatial expression patterns of these genes, which were modulated under abiotic stress. Among the identified StCaM genes, StCaM2 was found to have the largest number of abiotic stress responsive promoter elements. In addition, StCaM2 was upregulated in response to some of the selected abiotic stress in potato tissues. Overexpression of StCaM2 in transgenic tobacco plants enhanced their tolerance to salinity and drought stress. Accumulation of reactive oxygen species was remarkably decreased in transgenic lines compared to that in wild type plants. Chlorophyll a fluorescence analysis suggested better performance of photosystem II in transgenic plants under stress compared to that in wild type plants. The increase in salinity stress tolerance in StCaM2-overexpressing plants was also associated with a favorable K+/Na+ ratio. The enhanced tolerance to abiotic stresses correlated with the increase in the activities of anti-oxidative enzymes in transgenic tobacco plants. Overall, our results suggest that StCaM2 can be a novel candidate for conferring salt and drought tolerance in plants.
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Affiliation(s)
- Meenakshi Raina
- Department of Botany, Central University of Jammu, Rahya-Suchani (Bagla), Dist- Samba, Jammu and Kashmir, 181143, India
| | - Ashish Kumar
- Plant Molecular Biology Laboratory, Faculty of Life Sciences and Biotechnology, South Asian University, Akbar Bhawan, Chanakyapuri, New Delhi, 110021, India
| | - Nikita Yadav
- Plant Molecular Biology Laboratory, Faculty of Life Sciences and Biotechnology, South Asian University, Akbar Bhawan, Chanakyapuri, New Delhi, 110021, India
| | - Sumita Kumari
- Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, Jammu and Kashmir, India
| | - Mohd Aslam Yusuf
- Department of Bioengineering, Integral University, Dasauli, Kursi Road, Lucknow, 226026, India
| | - Ananda Mustafiz
- Plant Molecular Biology Laboratory, Faculty of Life Sciences and Biotechnology, South Asian University, Akbar Bhawan, Chanakyapuri, New Delhi, 110021, India.
| | - Deepak Kumar
- Department of Botany, Central University of Jammu, Rahya-Suchani (Bagla), Dist- Samba, Jammu and Kashmir, 181143, India.
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, 221005, Uttar Pradesh, India.
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Bombardi L, Pedretti M, Conter C, Dominici P, Astegno A. Distinct Calcium Binding and Structural Properties of Two Centrin Isoforms from Toxoplasma gondii. Biomolecules 2020; 10:E1142. [PMID: 32759683 PMCID: PMC7465447 DOI: 10.3390/biom10081142] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/27/2020] [Accepted: 07/31/2020] [Indexed: 11/16/2022] Open
Abstract
Centrins are calcium (Ca2+)-binding proteins that have been implicated in several regulatory functions. In the protozoan parasite Toxoplasma gondii, the causative agent of toxoplasmosis, three isoforms of centrin have been identified. While increasing information is now available that links the function of centrins with defined parasite biological processes, knowledge is still limited on the metal-binding and structural properties of these proteins. Herein, using biophysical and structural approaches, we explored the Ca2+ binding abilities and the subsequent effects of Ca2+ on the structure of a conserved (TgCEN1) and a more divergent (TgCEN2) centrin isoform from T. gondii. Our data showed that TgCEN1 and TgCEN2 possess diverse molecular features, suggesting that they play nonredundant roles in parasite physiology. TgCEN1 binds two Ca2+ ions with high/medium affinity, while TgCEN2 binds one Ca2+ with low affinity. TgCEN1 undergoes significant Ca2+-dependent conformational changes that expose hydrophobic patches, supporting a role as a Ca2+ sensor in toxoplasma. In contrast, Ca2+ binding has a subtle influence on conformational features of TgCEN2 without resulting in hydrophobic exposure, suggesting a different Ca2+ relay mode for this isoform. Furthermore, TgCEN1 displays a Ca2+-dependent ability to self-assemble, while TgCEN2 did not. We discuss our findings in the context of Ca2+ signaling in toxoplasma.
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Affiliation(s)
| | | | | | | | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy; (L.B.); (M.P.); (C.C.); (P.D.)
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Shen Q, Fu L, Su T, Ye L, Huang L, Kuang L, Wu L, Wu D, Chen ZH, Zhang G. Calmodulin HvCaM1 Negatively Regulates Salt Tolerance via Modulation of HvHKT1s and HvCAMTA4. PLANT PHYSIOLOGY 2020; 183:1650-1662. [PMID: 32554472 PMCID: PMC7401103 DOI: 10.1104/pp.20.00196] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/05/2020] [Indexed: 05/18/2023]
Abstract
Calcium (Ca2+) signaling modulates sodium (Na+) transport in plants; however, the role of the Ca2+ sensor calmodulin (CaM) in salt tolerance is elusive. We previously identified a salt-responsive calmodulin (HvCaM1) in a proteome study of barley (Hordeum vulgare) roots. Here, we employed bioinformatic, physiological, molecular, and biochemical approaches to determine the role of HvCaM1 in barley salt tolerance. CaM1s are highly conserved in green plants and probably originated from ancestors of green algae of the Chlamydomonadales order. HvCaM1 was mainly expressed in roots and was significantly up-regulated in response to long-term salt stress. Localization analyses revealed that HvCaM1 is an intracellular signaling protein that localizes to the root stele and vascular systems of barley. After treatment with 200 mm NaCl for 4 weeks, HvCaM1 knockdown (RNA interference) lines showed significantly larger biomass but lower Na+ concentration, xylem Na+ loading, and Na+ transportation rates in shoots compared with overexpression lines and wild-type plants. Thus, we propose that HvCaM1 is involved in regulating Na+ transport, probably via certain class I high-affinity potassium transporter (HvHKT1;5 and HvHKT1;1)-mediated Na+ translocation in roots. Moreover, we demonstrated that HvCaM1 interacted with a CaM-binding transcription activator (HvCAMTA4), which may be a critical factor in the regulation of HKT1s in barley. We conclude that HvCaM1 negatively regulates salt tolerance, probably via interaction with HvCAMTA4 to modulate the down-regulation of HvHKT1;5 and/or the up-regulation of HvHKT1;1 to reduce shoot Na+ accumulation under salt stress in barley.
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Affiliation(s)
- Qiufang Shen
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Liangbo Fu
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Tingting Su
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Lingzhen Ye
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Lu Huang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Liuhui Kuang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Liyuan Wu
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Dezhi Wu
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Zhong-Hua Chen
- School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales 2751, Australia
- Collaborative Innovation Centre for Grain Industry, College of Agriculture, Yangtze University, Jingzhou 434025, China
| | - Guoping Zhang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
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SAC3B is a target of CML19, the centrin 2 of Arabidopsis thaliana. Biochem J 2020; 477:173-189. [PMID: 31860002 DOI: 10.1042/bcj20190674] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/17/2019] [Accepted: 12/18/2019] [Indexed: 01/15/2023]
Abstract
Arabidopsis centrin 2, also known as calmodulin-like protein 19 (CML19), is a member of the EF-hand superfamily of calcium (Ca2+)-binding proteins. In addition to the notion that CML19 interacts with the nucleotide excision repair protein RAD4, CML19 was suggested to be a component of the transcription export complex 2 (TREX-2) by interacting with SAC3B. However, the molecular determinants of this interaction have remained largely unknown. Herein, we identified a CML19-binding site within the C-terminus of SAC3B and characterized the binding properties of the corresponding 26-residue peptide (SAC3Bp), which exhibits the hydrophobic triad centrin-binding motif in a reversed orientation (I8W4W1). Using a combination of spectroscopic and calorimetric experiments, we shed light on the SAC3Bp-CML19 complex structure in solution. We demonstrated that the peptide interacts not only with Ca2+-saturated CML19, but also with apo-CML19 to form a protein-peptide complex with a 1 : 1 stoichiometry. Both interactions involve hydrophobic and electrostatic contributions and include the burial of Trp residues of SAC3Bp. However, the peptide likely assumes different conformations upon binding to apo-CML19 or Ca2+-CML19. Importantly, the peptide dramatically increases the affinity for Ca2+ of CML19, especially of the C-lobe, suggesting that in vivo the protein would be Ca2+-saturated and bound to SAC3B even at resting Ca2+-levels. Our results, providing direct evidence that Arabidopsis SAC3B is a CML19 target and proposing that CML19 can bind to SAC3B through its C-lobe independent of a Ca2+ stimulus, support a functional role for these proteins in TREX-2 complex and mRNA export.
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Trande M, Pedretti M, Bonza MC, Di Matteo A, D'Onofrio M, Dominici P, Astegno A. Cation and peptide binding properties of CML7, a calmodulin-like protein from Arabidopsis thaliana. J Inorg Biochem 2019; 199:110796. [PMID: 31419675 DOI: 10.1016/j.jinorgbio.2019.110796] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/26/2019] [Accepted: 07/31/2019] [Indexed: 12/12/2022]
Abstract
Plants contain a large family of so-called calmodulin-like proteins (CMLs) which differ from canonical calmodulin in that they show greater variability in sequence, length, and number of EF-hand domains. The presence of this extended CML family has raised questions regarding the role of these proteins: are they functionally redundant or do they play specific functions in physiological plant processes? To answer these questions, comprehensive biochemical and structural information on CML proteins is fundamental. Among the 50 CMLs from Arabidopsis thaliana, herein we described the ability of CML7 to bind metal ions focusing on the Ca2+ and Mg2+ sensing properties, as well as on metal-induced conformational changes. Circular dichroism and nuclear magnetic resonance (NMR) studies indicated that both Ca2+ and Mg2+ stabilize CML7, as reflected in conformational rearrangements in secondary and tertiary structure and in increases in thermal stability of the protein. However, the conformational changes that binding induces differ between the two metal ions, and only Ca2+ binding controls a structural transition that leads to hydrophobic exposure, as suggested by 8-anilino-1-naphthalenesulfonic acid fluorescence. Isothermal titration calorimetry data coupled with NMR experiments revealed the presence of two high affinity Ca2+-binding sites in the C-lobe of CML7 and two weaker sites in the N-lobe. The paired nature of these CML7 EF-hands enables them to bind Ca2+ with positive cooperativity within each globular domain. Our results clearly place CML7 in the category of Ca2+ sensors. Along with this, the protein can bind to a model target peptide (melittin) in a Ca2+-dependent manner.
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Affiliation(s)
- Matteo Trande
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Marco Pedretti
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Maria Cristina Bonza
- Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy
| | - Adele Di Matteo
- Institute of Molecular Biology and Pathology, CNR, Piazzale Aldo Moro 5, Roma 00185, Italy
| | - Mariapina D'Onofrio
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Paola Dominici
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy
| | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
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12
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La Verde V, Dominici P, Astegno A. Towards Understanding Plant Calcium Signaling through Calmodulin-Like Proteins: A Biochemical and Structural Perspective. Int J Mol Sci 2018; 19:E1331. [PMID: 29710867 PMCID: PMC5983762 DOI: 10.3390/ijms19051331] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 11/17/2022] Open
Abstract
Ca2+ ions play a key role in a wide variety of environmental responses and developmental processes in plants, and several protein families with Ca2+-binding domains have evolved to meet these needs, including calmodulin (CaM) and calmodulin-like proteins (CMLs). These proteins have no catalytic activity, but rather act as sensor relays that regulate downstream targets. While CaM is well-studied, CMLs remain poorly characterized at both the structural and functional levels, even if they are the largest class of Ca2+ sensors in plants. The major structural theme in CMLs consists of EF-hands, and variations in these domains are predicted to significantly contribute to the functional versatility of CMLs. Herein, we focus on recent advances in understanding the features of CMLs from biochemical and structural points of view. The analysis of the metal binding and structural properties of CMLs can provide valuable insight into how such a vast array of CML proteins can coexist, with no apparent functional redundancy, and how these proteins contribute to cellular signaling while maintaining properties that are distinct from CaM and other Ca2+ sensors. An overview of the principal techniques used to study the biochemical properties of these interesting Ca2+ sensors is also presented.
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Affiliation(s)
- Valentina La Verde
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
| | - Paola Dominici
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
| | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy.
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13
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Ogunrinde A, Munro K, Davidson A, Ubaid M, Snedden WA. Arabidopsis Calmodulin-Like Proteins, CML15 and CML16 Possess Biochemical Properties Distinct from Calmodulin and Show Non-overlapping Tissue Expression Patterns. FRONTIERS IN PLANT SCIENCE 2017; 8:2175. [PMID: 29312414 PMCID: PMC5743801 DOI: 10.3389/fpls.2017.02175] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 12/12/2017] [Indexed: 05/20/2023]
Abstract
Calcium ions are used as ubiquitous, key second messengers in cells across eukaryotic taxa. In plants, calcium signal transduction is involved in a wide range of cellular processes from abiotic and biotic stress responses to development and growth. Calcium signals are detected by calcium sensor proteins, of which calmodulin (CaM), is the most evolutionarily conserved and well-studied. These sensors regulate downstream targets to propagate the information in signaling pathways. Plants possess a large family of calcium sensors related to CaM, termed CaM-like (CMLs), that are not found in animals and remain largely unstudied at the structural and functional level. Here, we investigated the biochemical properties and gene promoter activity of two closely related members of the Arabidopsis CML family, CML15 and CML16. Biochemical characterization of recombinant CML15 and CML16 indicated that they possess properties consistent with their predicted roles as calcium sensors. In the absence of calcium, CML15 and CML16 display greater intrinsic hydrophobicity than CaM. Both CMLs displayed calcium-dependent and magnesium-independent conformational changes that expose hydrophobic residues, but the degree of hydrophobic exposure was markedly less than that observed for CaM. Isothermal titration calorimetry indicated two and three calcium-binding sites for CML15 and CML16, respectively, with affinities expected to be within a physiological range. Both CML15 and CML16 bound calcium with high affinity in the presence of excess magnesium. Promoter-reporter analysis demonstrated that the CML16 promoter is active across a range of Arabidopsis tissues and developmental stages, whereas the CML15 promoter activity is very restricted and was observed only in floral tissues, specifically anthers and pollen. Collectively, our data indicate that these CMLs behave biochemically like calcium sensors but with properties distinct from CaM and likely have non-overlapping roles in floral development. We discuss our findings in the broader context of calcium sensors and signaling in Arabidopsis.
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Affiliation(s)
| | - Kim Munro
- Protein Function Discovery Laboratory, Department of Biomedical and Medical Sciences, Queen's University, Kingston, ON, Canada
| | | | - Midhat Ubaid
- Department of Biology, Queen's University, Kingston, ON, Canada
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14
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Jauregui E, Du L, Gleason C, Poovaiah BW. W342F Mutation in CCaMK Enhances Its Affinity to Calmodulin But Compromises Its Role in Supporting Root Nodule Symbiosis in Medicago truncatula. FRONTIERS IN PLANT SCIENCE 2017; 8:1921. [PMID: 29201032 PMCID: PMC5696362 DOI: 10.3389/fpls.2017.01921] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 10/24/2017] [Indexed: 06/07/2023]
Abstract
The calcium/calmodulin-dependent protein kinase (CCaMK) is regulated by free Ca2+ and Ca2+-loaded calmodulin. This dual binding is believed to be involved in its regulation and associated physiological functions, although direct experimental evidence for this is lacking. Here we document that site-directed mutations in the calmodulin-binding domain of CCaMK alters its binding capacity to calmodulin, providing an effective approach to study how calmodulin regulates CCaMK in terms of kinase activity and regulation of rhizobial symbiosis in Medicago truncatula. We observed that mutating the tryptophan at position 342 to phenylalanine (W342F) markedly increased the calmodulin-binding capability of the mutant. The mutant CCaMK underwent autophosphorylation and catalyzed substrate phosphorylation in the absence of calcium and calmodulin. When the mutant W342F was expressed in ccamk-1 roots, the transgenic roots exhibited an altered nodulation phenotype. These results indicate that altering the calmodulin-binding domain of CCaMK could generate a constitutively activated kinase with a negative role in the physiological function of CCaMK.
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Affiliation(s)
- Edgard Jauregui
- Laboratory of Molecular Plant Science, Department of Horticulture, Washington State University, Pullman, WA, United States
| | - Liqun Du
- Laboratory of Molecular Plant Science, Department of Horticulture, Washington State University, Pullman, WA, United States
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China
| | - Cynthia Gleason
- Department of Plant Pathology, Washington State University, Pullman, WA, United States
| | - B. W. Poovaiah
- Laboratory of Molecular Plant Science, Department of Horticulture, Washington State University, Pullman, WA, United States
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15
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La Verde V, Trande M, D'Onofrio M, Dominici P, Astegno A. Binding of calcium and target peptide to calmodulin-like protein CML19, the centrin 2 of Arabidopsis thaliana. Int J Biol Macromol 2017; 108:1289-1299. [PMID: 29129631 DOI: 10.1016/j.ijbiomac.2017.11.044] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 11/07/2017] [Accepted: 11/08/2017] [Indexed: 01/03/2023]
Abstract
Calmodulin-like protein 19 (CML19) is an Arabidopsis centrin that modulates nucleotide excision repair (NER) by binding to RAD4 protein, the Arabidopsis homolog of human Xeroderma pigmentosum complementation group C protein. Although the necessity of CML19 as a part of the RAD4 plant recognition complex for functional NER is known at a cellular level, little is known at a molecular level. Herein, we used a combination of biophysical and biochemical approaches to investigate the structural and ion and target-peptide binding properties of CML19. We found that CML19 possesses four Ca2+-specific binding sites, two of high affinity in the N-terminal domain and two of low affinity in the C-terminal domain. Binding of Ca2+ to CML19 increases its alpha-helix content, stabilizes the tertiary structure, and triggers a conformational change, resulting in the exposure of a hydrophobic patch instrumental for target protein recognition. Using bioinformatics tools we identified a CML19-binding site at the C-terminus of RAD4, and through in vitro binding experiments we analyzed the interaction between a 17-mer peptide representing this site and CML19. We found that the peptide shows a high affinity for CML19 in the presence of Ca2+ (stoichiometry 1:1) and the interaction primarily involves the C-terminal half of CML19.
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Affiliation(s)
- Valentina La Verde
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Italy
| | - Matteo Trande
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Italy
| | - Mariapina D'Onofrio
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Italy
| | - Paola Dominici
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Italy
| | - Alessandra Astegno
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Italy.
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16
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Astegno A, Bonza MC, Vallone R, La Verde V, D'Onofrio M, Luoni L, Molesini B, Dominici P. Arabidopsis calmodulin-like protein CML36 is a calcium (Ca 2+) sensor that interacts with the plasma membrane Ca 2+-ATPase isoform ACA8 and stimulates its activity. J Biol Chem 2017; 292:15049-15061. [PMID: 28726644 PMCID: PMC5592680 DOI: 10.1074/jbc.m117.787796] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 07/07/2017] [Indexed: 11/06/2022] Open
Abstract
Calmodulin-like (CML) proteins are major EF-hand-containing, calcium (Ca2+)-binding proteins with crucial roles in plant development and in coordinating plant stress tolerance. Given their abundance in plants, the properties of Ca2+ sensors and identification of novel target proteins of CMLs deserve special attention. To this end, we recombinantly produced and biochemically characterized CML36 from Arabidopsis thaliana We analyzed Ca2+ and Mg2+ binding to the individual EF-hands, observed metal-induced conformational changes, and identified a physiologically relevant target. CML36 possesses two high-affinity Ca2+/Mg2+ mixed binding sites and two low-affinity Ca2+-specific sites. Binding of Ca2+ induced an increase in the α-helical content and a conformational change that lead to the exposure of hydrophobic regions responsible for target protein recognition. Cation binding, either Ca2+ or Mg2+, stabilized the secondary and tertiary structures of CML36, guiding a large structural transition from a molten globule apo-state to a compact holoconformation. Importantly, through in vitro binding and activity assays, we showed that CML36 interacts directly with the regulative N terminus of the Arabidopsis plasma membrane Ca2+-ATPase isoform 8 (ACA8) and that this interaction stimulates ACA8 activity. Gene expression analysis revealed that CML36 and ACA8 are co-expressed mainly in inflorescences. Collectively, our results support a role for CML36 as a Ca2+ sensor that binds to and modulates ACA8, uncovering a possible involvement of the CML protein family in the modulation of plant-autoinhibited Ca2+ pumps.
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Affiliation(s)
- Alessandra Astegno
- From the Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy and
| | - Maria Cristina Bonza
- the Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy
| | - Rosario Vallone
- From the Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy and
| | - Valentina La Verde
- From the Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy and
| | - Mariapina D'Onofrio
- From the Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy and
| | - Laura Luoni
- the Department of Biosciences, University of Milano, Via Celoria 26, 20133 Milano, Italy
| | - Barbara Molesini
- From the Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy and
| | - Paola Dominici
- From the Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona, Italy and
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17
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Liao J, Deng J, Qin Z, Tang J, Shu M, Ding C, Liu J, Hu C, Yuan M, Huang Y, Yang R, Zhou Y. Genome-Wide Identification and Analyses of Calmodulins and Calmodulin-like Proteins in Lotus japonicas. FRONTIERS IN PLANT SCIENCE 2017; 8:482. [PMID: 28424729 PMCID: PMC5380670 DOI: 10.3389/fpls.2017.00482] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/20/2017] [Indexed: 05/10/2023]
Abstract
L. japonicus, a model plant of legumes plants, is widely used in symbiotic nitrogen fixation. A large number of studies on it have been published based on the genetic, biochemical, structural studies. These results are secondhand reports that CaM is a key regulator during Rhizobial infection. In plants, there are multiple CaM genes encoding several CaM isoforms with only minor amino acid differences. Moreover, the regulation mechanism of this family of proteins during rhizobia infection is still unclear. In the current study, a family of genes encoding CaMs and CMLs that possess only the Ca2+-binding EF-hand motifs were analyzed. Using ML and BI tree based on amino acid sequence similarity, seven loci defined as CaMs and 19 CMLs, with at least 23% identity to CaM, were identified. The phylogenetics, gene structures, EF hand motif organization, and expression characteristics were evaluated. Seven CaM genes, encoding only 4 isoforms, were found in L. japonicus. According to qRT-PCR, four LjCaM isoforms are involved in different rhizobia infection stages. LjCaM1 might be involved in the early rhizobia infection epidermal cells stage. Furthermore, additional structural differences and expression behaviors indicated that LjCMLs may have different potential functions from LjCaMs.
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Affiliation(s)
- Jinqiu Liao
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Jiabin Deng
- School of Geography and Tourism, Guizhou Education UniversityGuiyang, China
| | - Zongzhi Qin
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Jiayong Tang
- Animal Nutrition Institute, Sichuan Agricultural UniversityChengdu, China
| | - Maorong Shu
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Chunbang Ding
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Jing Liu
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Chao Hu
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Ming Yuan
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Yan Huang
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Ruiwu Yang
- College of Life Sciences, Sichuan Agricultural UniversityYaan, China
| | - Yonghong Zhou
- Triticeae Research Institute, Sichuan Agricultural UniversityChengdu, China
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18
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Ababou A, Zaleska M, Pfuhl M. On the Ca 2+ binding and conformational change in EF-hand domains: Experimental evidence of Ca 2+-saturated intermediates of N-domain of calmodulin. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:640-651. [PMID: 28288938 DOI: 10.1016/j.bbapap.2017.03.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 03/07/2017] [Accepted: 03/09/2017] [Indexed: 02/07/2023]
Abstract
Double mutation of Q41L and K75I in the N-domain of calmodulin (N-Cam) stabilizes the closed form of N-Cam such that binding of Ca2+ in solution no longer triggers a conformational change to the open form, and its Ca2+ binding affinity decreases dramatically. To further investigate the solvation effects on the structure, Ca2+ binding affinity and conformational dynamics of this N-Cam double mutant in the Ca2+ saturated state, we solved its X-ray structure. Surprisingly, the structure revealed an open conformation of the domain which contradicts its closed conformation in solution. Here we provide evidence that crystallization conditions were responsible for this Ca2+-saturated domain open conformation in the crystal. Importantly, we demonstrate that the presence of the crystallization co-precipitant and alcohols were able to induce a progressive opening of the closed form of this domain, in Ca2+ saturated state, in solution. However, in the Ca2+ depleted state, addition of alcohols was unable to induce any opening of this domain in solution. In addition, in the Ca2+ saturated state, the molecular dynamics simulations show that while N-Cam can populate the open and closed conformation, the N-Cam double mutant exclusively populates the closed conformation. Our results provide experimental evidence of intermediate conformations of Ca2+-saturated N-Cam in solution. We propose that conformational change of Ca2+ sensor EF-hand domains depends on solvation energetics, Ca2+ binding to promote the full open form, Ca2+ depleted state conformational dynamics, and the chemical properties of the molecules nearby key residues such as those at positions 41 and 75 in N-Cam.
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Affiliation(s)
- Abdessamad Ababou
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK; University of East London, School of Health, Sport and Bioscience, Water Lane, London E15 4LZ, UK.
| | - Mariola Zaleska
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Mark Pfuhl
- Cardiovascular and Randall Division, King's College London, London SE1 1UL, UK
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19
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Walton SD, Chakravarthy H, Shettigar V, O’Neil AJ, Siddiqui JK, Jones BR, Tikunova SB, Davis JP. Divergent Soybean Calmodulins Respond Similarly to Calcium Transients: Insight into Differential Target Regulation. FRONTIERS IN PLANT SCIENCE 2017; 8:208. [PMID: 28261258 PMCID: PMC5309217 DOI: 10.3389/fpls.2017.00208] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 02/03/2017] [Indexed: 05/07/2023]
Abstract
Plants commonly respond to stressors by modulating the expression of a large family of calcium binding proteins including isoforms of the ubiquitous signaling protein calmodulin (CaM). The various plant CaM isoforms are thought to differentially regulate the activity of specific target proteins to modulate cellular stress responses. The mechanism(s) behind differential target activation by the plant CaMs is unknown. In this study, we used steady-state and stopped-flow fluorescence spectroscopy to investigate the strategy by which two soybean CaMs (sCaM1 and sCaM4) have evolved to differentially regulate NAD kinase (NADK), which is activated by sCaM1 but inhibited by sCaM4. Although the isolated proteins have different cation binding properties, in the presence of Mg2+ and the CaM binding domains from proteins that are differentially regulated, the two plant CaMs respond nearly identically to rapid and slow Ca2+ transients. Our data suggest that the plant CaMs have evolved to bind certain targets with comparable affinities, respond similarly to a particular Ca2+ signature, but achieve different structural states, only one of which can activate the enzyme. Understanding the basis for differential enzyme regulation by the plant CaMs is the first step to engineering a vertebrate CaM that will selectively alter the CaM signaling network.
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Affiliation(s)
| | | | | | | | | | | | | | - Jonathan P. Davis
- Department of Physiology and Cell Biology, The Ohio State UniversityColumbus, OH, USA
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20
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Astegno A, La Verde V, Marino V, Dell'Orco D, Dominici P. Biochemical and biophysical characterization of a plant calmodulin: Role of the N- and C-lobes in calcium binding, conformational change, and target interaction. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1864:297-307. [PMID: 26708477 DOI: 10.1016/j.bbapap.2015.12.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 11/29/2015] [Accepted: 12/09/2015] [Indexed: 12/22/2022]
Abstract
In plants, transient elevation of intracellular Ca(2+) concentration in response to abiotic stress is responsible for glutamate decarboxylase (GAD) activation via association with calmodulin (CaM), an EF-hand protein consisting of two homologous domains (N and C). An unusual 1:2 binding mode of CaM to CaM-binding domains of GAD has long been known, however the contribution of the two CaM domains in target recognition and activation remains to be clarified. Here, we explored the coupling between physicochemical properties of Arabidopsis CaM1 (AtCaM1) and Arabidopsis GAD1 activation, focusing on each AtCaM1 lobe. We found that the four EF-loops of AtCaM1 differently contribute to the ~20 μM apparent affinity for Ca(2+) and the C-lobe shows a ~6-fold higher affinity than N-lobe (Kd(app) 5.6 μM and 32 μM for C- and N-lobes, respectively). AtCaM1 responds structurally to Ca(2+) in a manner similar to vertebrate CaM based on comparison of Ca(2+)-induced changes in hydrophobicity exposure, secondary structure, and hydrodynamic behavior. Molecular dynamics simulations of AtCaM1 apo and Ca(2+)-bound reveal that the latter state is significantly less flexible, although regions of the N-lobe remain quite flexible; this suggests the importance of N-lobe for completing the transition to the extended structure of holoprotein, consistent with data from ANS fluorescence, CD spectroscopy, and SEC analysis. Moreover, enzymatic analysis reveal that mutations in the two lobes affect GAD1 activation in similar ways and only intact AtCaM1 can fully activate GAD1. Taken together, our data provide new insights into the CaM lobes role in interactions between CaM and plant GAD.
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Affiliation(s)
| | | | - Valerio Marino
- Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Daniele Dell'Orco
- Department of Neurological, Biomedical and Movement Sciences, University of Verona, Verona, Italy
| | - Paola Dominici
- Department of Biotechnology, University of Verona, Verona, Italy
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21
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Campe R, Langenbach C, Leissing F, Popescu GV, Popescu SC, Goellner K, Beckers GJM, Conrath U. ABC transporter PEN3/PDR8/ABCG36 interacts with calmodulin that, like PEN3, is required for Arabidopsis nonhost resistance. THE NEW PHYTOLOGIST 2016; 209:294-306. [PMID: 26315018 DOI: 10.1111/nph.13582] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 06/30/2015] [Indexed: 05/20/2023]
Abstract
Nonhost resistance (NHR) is the most prevalent form of plant immunity. In Arabidopsis, NHR requires membrane-localized ATP-binding cassette (ABC) transporter PENETRATION (PEN) 3. Upon perception of pathogen-associated molecular patterns, PEN3 becomes phosphorylated, suggestive of PEN3 regulation by post-translational modification. Here, we investigated the PEN3 protein interaction network. We probed the Arabidopsis protein microarray AtPMA-5000 with the N-terminal cytoplasmic domain of PEN3. Several of the proteins identified to interact with PEN3 in vitro represent cellular Ca(2+) sensors, including calmodulin (CaM) 3, CaM7 and several CaM-like proteins, pointing to the importance of Ca(2+) sensing to PEN3-mediated NHR. We demonstrated co-localization of PEN3 and CaM7, and we confirmed PEN3-CaM interaction in vitro and in vivo by PEN3 pull-down with CaM Sepharose, CaM overlay assay and bimolecular fluorescence complementation. We also show that just like in pen3, NHR to the nonadapted fungal pathogens Phakopsora pachyrhizi and Blumeria graminis f.sp. hordei is compromised in the Arabidopsis cam7 and pen3 cam7 mutants. Our study discloses CaM7 as a PEN3-interacting protein crucial to Arabidopsis NHR and emphasizes the importance of Ca(2+) sensing to plant immunity.
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Affiliation(s)
- Ruth Campe
- Department of Plant Physiology, RWTH Aachen University, Aachen, 52056, Germany
| | - Caspar Langenbach
- Department of Plant Physiology, RWTH Aachen University, Aachen, 52056, Germany
| | - Franz Leissing
- Department of Plant Physiology, RWTH Aachen University, Aachen, 52056, Germany
| | - George V Popescu
- Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853-1801, USA
- National Institute for Laser, Plasma & Radiation Physics, Str. Atomistilor, Nr. 409, Magurele, 077125, Bucharest, Romania
| | - Sorina C Popescu
- Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853-1801, USA
| | - Katharina Goellner
- Department of Plant Physiology, RWTH Aachen University, Aachen, 52056, Germany
| | - Gerold J M Beckers
- Department of Plant Physiology, RWTH Aachen University, Aachen, 52056, Germany
| | - Uwe Conrath
- Department of Plant Physiology, RWTH Aachen University, Aachen, 52056, Germany
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22
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Kissoudis C, van de Wiel C, Visser RGF, van der Linden G. Enhancing crop resilience to combined abiotic and biotic stress through the dissection of physiological and molecular crosstalk. FRONTIERS IN PLANT SCIENCE 2014; 5:207. [PMID: 24904607 PMCID: PMC4032886 DOI: 10.3389/fpls.2014.00207] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 04/28/2014] [Indexed: 05/18/2023]
Abstract
Plants growing in their natural habitats are often challenged simultaneously by multiple stress factors, both abiotic and biotic. Research has so far been limited to responses to individual stresses, and understanding of adaptation to combinatorial stress is limited, but indicative of non-additive interactions. Omics data analysis and functional characterization of individual genes has revealed a convergence of signaling pathways for abiotic and biotic stress adaptation. Taking into account that most data originate from imposition of individual stress factors, this review summarizes these findings in a physiological context, following the pathogenesis timeline and highlighting potential differential interactions occurring between abiotic and biotic stress signaling across the different cellular compartments and at the whole plant level. Potential effects of abiotic stress on resistance components such as extracellular receptor proteins, R-genes and systemic acquired resistance will be elaborated, as well as crosstalk at the levels of hormone, reactive oxygen species, and redox signaling. Breeding targets and strategies are proposed focusing on either manipulation and deployment of individual common regulators such as transcription factors or pyramiding of non- (negatively) interacting components such as R-genes with abiotic stress resistance genes. We propose that dissection of broad spectrum stress tolerance conferred by priming chemicals may provide an insight on stress cross regulation and additional candidate genes for improving crop performance under combined stress. Validation of the proposed strategies in lab and field experiments is a first step toward the goal of achieving tolerance to combinatorial stress in crops.
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