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Price BD, Sojka A, Maity S, Chavez IM, Starck M, Wilson MZ, Han S, Sherwin MS. Field-domain rapid-scan EPR at 240GHz for studies of protein functional dynamics at room temperature. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 366:107744. [PMID: 39096714 DOI: 10.1016/j.jmr.2024.107744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 07/22/2024] [Accepted: 07/24/2024] [Indexed: 08/05/2024]
Abstract
We present field-domain rapid-scan (RS) electron paramagnetic resonance (EPR) at 8.6T and 240GHz. To enable this technique, we upgraded a home-built EPR spectrometer with an FPGA-enabled digitizer and real-time processing software. The software leverages the Hilbert transform to recover the in-phase (I) and quadrature (Q) channels, and therefore the raw absorptive and dispersive signals, χ' and χ'', from their combined magnitude (I2+Q2). Averaging a magnitude is simpler than real-time coherent averaging and has the added benefit of permitting long-timescale signal averaging (up to at least 2.5×106 scans) because it eliminates the effects of source-receiver phase drift. Our rapid-scan (RS) EPR provides a signal-to-noise ratio that is approximately twice that of continuous wave (CW) EPR under the same experimental conditions, after scaling by the square root of acquisition time. We apply our RS EPR as an extension of the recently reported time-resolved Gd-Gd EPR (TiGGER) [Maity et al., 2023], which is able to monitor inter-residue distance changes during the photocycle of a photoresponsive protein through changes in the Gd-Gd dipolar couplings. RS, opposed to CW, returns field-swept spectra as a function of time with 10ms time resolution, and thus, adds a second dimension to the static field transients recorded by TiGGER. We were able to use RS TiGGER to track time-dependent and temperature-dependent kinetics of AsLOV2, a light-activated phototropin domain found in oats. The results presented here combine the benefits of RS EPR with the improved spectral resolution and sensitivity of Gd chelates at high magnetic fields. In the future, field-domain RS EPR at high magnetic fields may enable studies of other real-time kinetic processes with time resolutions that are otherwise difficult to access in the solution state.
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Affiliation(s)
- Brad D Price
- Department of Physics, University of California, Santa Barbara, 93106, CA, USA; Institute for Terahertz Science and Technology, University of California, Santa Barbara, 93106, CA, USA.
| | - Antonín Sojka
- Department of Physics, University of California, Santa Barbara, 93106, CA, USA; Institute for Terahertz Science and Technology, University of California, Santa Barbara, 93106, CA, USA
| | - Shiny Maity
- Department of Chemistry, University of California, Santa Barbara, 93106, CA, USA; Department of Chemistry, Northwestern University, 633 Clark Street, Evanston, 60208, IL, USA
| | - I Marcelo Chavez
- Department of Chemistry, University of California, Santa Barbara, 93106, CA, USA
| | - Matthieu Starck
- Department of Chemistry, Durham University, Durham, DH13LE, UK
| | - Maxwell Z Wilson
- Department Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, 93106, CA, USA
| | - Songi Han
- Department of Chemistry, University of California, Santa Barbara, 93106, CA, USA; Department of Chemistry, Northwestern University, 633 Clark Street, Evanston, 60208, IL, USA
| | - Mark S Sherwin
- Department of Physics, University of California, Santa Barbara, 93106, CA, USA; Institute for Terahertz Science and Technology, University of California, Santa Barbara, 93106, CA, USA.
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Waksman T, Suetsugu N, Hermanowicz P, Ronald J, Sullivan S, Łabuz J, Christie JM. Phototropin phosphorylation of ROOT PHOTOTROPISM 2 and its role in mediating phototropism, leaf positioning, and chloroplast accumulation movement in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 114:390-402. [PMID: 36794876 PMCID: PMC10953443 DOI: 10.1111/tpj.16144] [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: 11/29/2022] [Accepted: 02/08/2023] [Indexed: 05/10/2023]
Abstract
Directional movements impact the ability of plants to respond and adjust their growth accordingly to the prevailing light environment. The plasma-membrane associated protein, ROOT PHOTOTROPISM 2 (RPT2) is a key signalling component involved in chloroplast accumulation movement, leaf positioning, and phototropism, all of which are regulated redundantly by the ultraviolet/blue light-activated AGC kinases phototropin 1 and 2 (phot1 and phot2). We recently demonstrated that members of the NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3)/RPT2-like (NRL) family in Arabidopsis thaliana, including RPT2, are directly phosphorylated by phot1. However, whether RPT2 is a substrate for phot2, and the biological significance of phot phosphorylation of RPT2 remains to be determined. Here, we show that RPT2 is phosphorylated by both phot1 and phot2 at a conserved serine residue (S591) within the C-terminal region of the protein. Blue light triggered the association of 14-3-3 proteins with RPT2 consistent with S591 acting as a 14-3-3 binding site. Mutation of S591 had no effect on the plasma membrane localization of RPT2 but reduced its functionality for leaf positioning and phototropism. Moreover, our findings indicate that S591 phosphorylation within the C-terminus of RPT2 is required for chloroplast accumulation movement to low level blue light. Taken together, these findings further highlight the importance of the C-terminal region of NRL proteins and how its phosphorylation contributes to phot receptor signalling in plants.
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Affiliation(s)
- Thomas Waksman
- School of Molecular BiosciencesCollege of Medical, Veterinary and Life Sciences, University of GlasgowBower BuildingGlasgowG12 8QQUK
| | - Noriyuki Suetsugu
- School of Molecular BiosciencesCollege of Medical, Veterinary and Life Sciences, University of GlasgowBower BuildingGlasgowG12 8QQUK
- Graduate School of Arts and SciencesThe University of TokyoTokyo153‐8902Japan
| | - Pawel Hermanowicz
- Malopolska Centre of BiotechnologyJagiellonian UniversityGronostajowa 7A30‐387KrakówPoland
| | - James Ronald
- School of Molecular BiosciencesCollege of Medical, Veterinary and Life Sciences, University of GlasgowBower BuildingGlasgowG12 8QQUK
| | - Stuart Sullivan
- School of Molecular BiosciencesCollege of Medical, Veterinary and Life Sciences, University of GlasgowBower BuildingGlasgowG12 8QQUK
| | - Justyna Łabuz
- Malopolska Centre of BiotechnologyJagiellonian UniversityGronostajowa 7A30‐387KrakówPoland
| | - John M. Christie
- School of Molecular BiosciencesCollege of Medical, Veterinary and Life Sciences, University of GlasgowBower BuildingGlasgowG12 8QQUK
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Crump MC, Brown C, Griffin-Nolan RJ, Angeloni L, Lemoine NP, Seymoure BM. Effects of Low-Level Artificial Light at Night on Kentucky Bluegrass and an Introduced Herbivore. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.732959] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Increasing evidence suggests that artificial light at night (ALAN) can negatively impact organisms. However, most studies examine the impacts of ALAN on a single species or under high levels of artificial light that are infrequent or unrealistic in urban environments. We currently have little information on how low levels of artificial light emanating from urban skyglow affect plants and their interactions with herbivores. We examined how short-term, low levels of ALAN affect grass and insects, including growth rate, photosynthesis, and stomatal conductance in grass, and foraging behavior and survival in crickets. We compared growth and leaf-level gas exchange of Kentucky Bluegrass (Poa pratensis) under low-levels of ALAN (0.3 lux) and starlight conditions (0.001 lux). Furthermore, each light treatment was divided into treatments with and without house crickets (Acheta domesticus). Without crickets present, bluegrass grown under ALAN for three weeks grew taller than plants grown under natural night light levels. In the fourth week when crickets were introduced, grass height decreased resulting in no measurable effects of light treatment. There were no measurable differences in grass physiology among treatments. Our results indicate that low levels of light resulting from skyglow affect plant growth initially. However, with herbivory, the effects of ALAN on grass may be inconsequential. Gaining an understanding of how ALAN affects plant-insect interactions is critical to predicting the ecological and evolutionary consequences of anthropogenic light pollution.
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Matsuoka D, Iwata T, Zikihara K, Kandori H, Tokutomi S. Primary processes during the light-signal transduction of phototropin. Photochem Photobiol 2007; 83:122-30. [PMID: 16802859 DOI: 10.1562/2006-03-29-ra-861] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Phototropin is a blue-light photoreceptor in plants that mediates phototropism, chloroplast relocation, stomata opening and leaf expansion. Phototropin molecule has two photoreceptive domains named LOV1 (light-oxygen-voltage) and LOV2 in the N-terminus and a serine/threonine kinase domain in the C-terminus, and acts as a blue light-regulated kinase. Each LOV domain binds a flavin mononucleotide as a chromophore and undergoes unique cyclic reactions upon blue-light absorption that comprises a cysteinyl-flavin adduct formation through a triplet-excited state and a successive adduct break to revert to the initial ground state. The molecular reactions underlying the photocycle are reviewed and one of the probable molecular schemes is presented. Adduct formation alters the secondary protein structure of the LOV domains. This structural change could be transferred to the linker between the kinase domain and involved in the photoregulation of the kinase activity. The structural changes as well as the oligomeric structures seem to differ between LOV1 and LOV2, which may explain the proposed roles of each domain in the photoregulation of the kinase activity. The photoregulation mechanism of phototropin kinase is reviewed and discussed in reference to the regulation mechanism of protein kinase A, which it resembles.
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Affiliation(s)
- Daisuke Matsuoka
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Naka-ku, Sakai, Osaka, Japan
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