{"title":"Cyclic AMP-regulatory element-binding protein: a novel UV-targeted transcription factor in skin cancer.","authors":"Julianne C Nayar, Myriam Abboud, Katie M Dixon","doi":"10.1007/s43630-024-00578-7","DOIUrl":"10.1007/s43630-024-00578-7","url":null,"abstract":"<p><p>Common therapeutics in relation to melanoma and non-melanoma cancers include the use of kinase inhibitors. The long-term benefits of kinases, however, are limited by development of drug resistance. An alternative approach for treatment would be to focus on transcription factors. Cyclic AMP-regulatory element-binding protein (CREB) is a transcription factor that is commonly overactivated or overexpressed in many different cancers including skin cancer. Ultraviolet radiation (UVR), one of the main causes of skin cancer, can activate CREB in both melanocytes and keratinocytes. In addition, CREB has been found to be activated in skin cancers. Considering the prominent role that CREB plays in skin cancers, the studies reviewed herein raise the possibility of CREB as a potential prognostic and diagnostic marker of skin cancer and a novel target for therapeutic intervention.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1209-1215"},"PeriodicalIF":3.1,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140924327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S Madronich, G H Bernhard, P J Neale, A Heikkilä, M P Sulbæk Andersen, A L Andrady, P J Aucamp, A F Bais, A T Banaszak, P J Barnes, J F Bornman, L S Bruckman, R Busquets, G Chiodo, D-P Häder, M L Hanson, S Hylander, M A K Jansen, G Lingham, R M Lucas, R Mackenzie Calderon, C Olsen, R Ossola, K K Pandey, I Petropavlovskikh, L E Revell, L E Rhodes, S A Robinson, T M Robson, K C Rose, T Schikowski, K R Solomon, B Sulzberger, T J Wallington, Q-W Wang, S-Å Wängberg, C C White, S R Wilson, L Zhu, R E Neale
{"title":"Continuing benefits of the Montreal Protocol and protection of the stratospheric ozone layer for human health and the environment.","authors":"S Madronich, G H Bernhard, P J Neale, A Heikkilä, M P Sulbæk Andersen, A L Andrady, P J Aucamp, A F Bais, A T Banaszak, P J Barnes, J F Bornman, L S Bruckman, R Busquets, G Chiodo, D-P Häder, M L Hanson, S Hylander, M A K Jansen, G Lingham, R M Lucas, R Mackenzie Calderon, C Olsen, R Ossola, K K Pandey, I Petropavlovskikh, L E Revell, L E Rhodes, S A Robinson, T M Robson, K C Rose, T Schikowski, K R Solomon, B Sulzberger, T J Wallington, Q-W Wang, S-Å Wängberg, C C White, S R Wilson, L Zhu, R E Neale","doi":"10.1007/s43630-024-00577-8","DOIUrl":"10.1007/s43630-024-00577-8","url":null,"abstract":"<p><p>The protection of Earth's stratospheric ozone (O<sub>3</sub>) is an ongoing process under the auspices of the universally ratified Montreal Protocol and its Amendments and adjustments. A critical part of this process is the assessment of the environmental issues related to changes in O<sub>3</sub>. The United Nations Environment Programme's Environmental Effects Assessment Panel provides annual scientific evaluations of some of the key issues arising in the recent collective knowledge base. This current update includes a comprehensive assessment of the incidence rates of skin cancer, cataract and other skin and eye diseases observed worldwide; the effects of UV radiation on tropospheric oxidants, and air and water quality; trends in breakdown products of fluorinated chemicals and recent information of their toxicity; and recent technological innovations of building materials for greater resistance to UV radiation. These issues span a wide range of topics, including both harmful and beneficial effects of exposure to UV radiation, and complex interactions with climate change. While the Montreal Protocol has succeeded in preventing large reductions in stratospheric O<sub>3</sub>, future changes may occur due to a number of natural and anthropogenic factors. Thus, frequent assessments of potential environmental impacts are essential to ensure that policies remain based on the best available scientific knowledge.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1087-1115"},"PeriodicalIF":3.1,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141066669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Near-infrared two-photon absorption and excited state dynamics of a fluorescent diarylethene derivative.","authors":"Hikaru Sotome, Tatsuhiro Nagasaka, Tatsuki Konishi, Kenji Kamada, Masakazu Morimoto, Masahiro Irie, Hiroshi Miyasaka","doi":"10.1007/s43630-024-00573-y","DOIUrl":"10.1007/s43630-024-00573-y","url":null,"abstract":"<p><p>Near-infrared two-photon absorption and excited state dynamics of a fluorescent diarylethene (fDAE) derivative were investigated by time-resolved absorption and fluorescence spectroscopies. Prescreening with quantum chemical calculation predicted that a derivative with methylthienyl groups (mt-fDAE) in the closed-ring isomer has a two-photon absorption cross-section larger than 1000 GM, which was experimentally verified by Z-scan measurements and excitation power dependence in transient absorption. Comparison of transient absorption spectra under one-photon and simultaneous two-photon excitation conditions revealed that the closed-ring isomer of mt-fDAE populated into higher excited states deactivates following three pathways on a timescale of ca. 200 fs: (i) the cycloreversion reaction more efficient than that by the one-photon process, (ii) internal conversion into the S<sub>1</sub> state, and (iii) relaxation into a lower state (S<sub>1</sub>' state) different from the S<sub>1</sub> state. Time-resolved fluorescence measurements demonstrated that this S<sub>1</sub>' state is relaxed to the S<sub>1</sub> state with the large emission probability. These findings obtained in the present work contribute to extension of the ON-OFF switching capability of fDAE to the biological window and application to super-resolution fluorescence imaging in a two-photon manner.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1041-1050"},"PeriodicalIF":3.1,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140875277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Andreas Fellner, Nikolaus Bresgen, Michael Fefer, Jun Liu, Kristjan Plaetzer
{"title":"Fly into the light: eliminating Drosophila melanogaster with chlorophyllin-based Photodynamic Inactivation.","authors":"Andreas Fellner, Nikolaus Bresgen, Michael Fefer, Jun Liu, Kristjan Plaetzer","doi":"10.1007/s43630-024-00583-w","DOIUrl":"10.1007/s43630-024-00583-w","url":null,"abstract":"<p><p>Fruit flies spoil crops in agricultural settings. As conventional pesticides may generate negative off-target effects on humans or the environment, existing treatment methods need eco-friendly and safe alternatives. Photodynamic Inactivation (PDI) is based on the photosensitizer-mediated and light-induced overproduction of reactive oxygen species in targets. We here explore the potential of PDI for the control of fruit fly pests. Drosophila melanogaster serves as well-established model organism in this study. Two distinct experimental approaches are presented: the feed assay, in which fruit flies are provided with sodium magnesium chlorophyllin (Chl, approved as food additive E140) along with sucrose (3%) as their food, and the spray assay, where the photosensitizer is sprayed onto the insects. We show that PDI based on Chl can induce moribundity rates of Drosophila melanogaster of more than 99% with 5 mM Chl and LED illumination (395 nm, 8 h incubation in the dark, radiant exposure 78.9 J/cm<sup>2</sup>) with the feed assay. If the radiant exposure is doubled to 157.8 J/cm<sup>2</sup>, 88% of insects are killed by PDI based on 1 mM Chl. The photoactive compound is also effective if presented on strawberries without addition of sucrose with somewhat lower moribundity (71% at 5 mM Chl). Spraying Chl onto insects is less effective than feeding the photosensitizer: 5 mM Chl resulted in 79.5% moribundity (drug to light interval 8 h, radiant exposure 78.9 J/cm<sup>2</sup>), but if 5 h of sun light (532 J/cm<sup>2</sup>) and overnight (14 h) dark incubation is used for activation of Chl, more than 95% of insects are killed. As conclusion, Chl serves as effective photoinsecticide against Drosophila melanogaster if a drug to light interval of 8 h is maintained. Feeding the photoactive compound together with sucrose is more effective than spraying it onto insects and increasing the radiant exposure allows for lowering the photosensitizer concentration. Photodynamic Inactivation might therefore represent an eco-friendly addition to the farmers armamentarium against (semi-transparent) insects.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1155-1166"},"PeriodicalIF":2.7,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140910779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Li-Hao Liu, Xian-Zhao Shang, Jian-Hao Yuan, Yi-Ning Luo, Jia-Yi Wang, Xiao-Lei Xue, Nan Jiang, Kun-Peng Wang, Zhi-Qiang Hu
{"title":"A fluorescent probe based on cyclochalcone for detecting peroxynitrite.","authors":"Li-Hao Liu, Xian-Zhao Shang, Jian-Hao Yuan, Yi-Ning Luo, Jia-Yi Wang, Xiao-Lei Xue, Nan Jiang, Kun-Peng Wang, Zhi-Qiang Hu","doi":"10.1007/s43630-024-00565-y","DOIUrl":"10.1007/s43630-024-00565-y","url":null,"abstract":"<p><p>A novel cyclic chalcone fluorescent probe C-PN was synthesized to detect ONOO<sup>-</sup>. After reaction with peroxynitrite, the double bond of C-PN in the cyclic chalcone structure was disconnected, which caused the change of intramolecular charge transfer (ICT) effect, emitting blue fluorescence and quenching orange red fluorescence. Visible to the naked eye, the color of the probe solution changed. The probe showed low sensitivity (detection limit = 20.2 nm), short response time (less than 60 s) at low concentration of ONOO<sup>-</sup>, good visibility, and good selectivity and stability for ONOO<sup>-</sup>.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1031-1039"},"PeriodicalIF":3.1,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141260245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Photostability and photodynamic antimicrobial profile of dye extracts from four (4) plants: prospects for eco-friendly low-cost food disinfection and topical biomedical applications.","authors":"Hussaini Majiya, Aliyu Adamu, Anzhela Galstyan","doi":"10.1007/s43630-024-00585-8","DOIUrl":"10.1007/s43630-024-00585-8","url":null,"abstract":"<p><p>In this study, photostability and photodynamic antimicrobial performance of dye extracts from Hibiscus sabdariffa (HS) calyces, Sorghum bicolor (SB) leaf sheaths, Lawsonia inermis (LI) leaves and Curcuma longa (CL) roots were investigated in Acetate-HCl (AH) Buffer (pH 4.6), Tris Base-HCl (TBH) Buffer (pH 8.6), distilled water (dH<sub>2</sub>O), and Phosphate Buffer Saline (PBS, pH 7.2) using Bacillus subtilis as model for gram positive bacteria, Escherichia coli as model for gram negative bacteria, phage MS2 as model for non-envelope viruses and phage phi6 as model for envelope viruses including SARS CoV-2 which is the causative agent of COVID-19. Our results showed that the photostability of the dye extracts is in the decreasing order of LI > CL > SB > HS. The dye extract-HS is photostable in dH<sub>2</sub>O but bleaches in buffers-AH, TBH and PBS. The rate of bleaching is higher in AH compared to in TBH and PBS. The bleaching and buffers affected the photodynamic and non-photodynamic antimicrobial activity of the dye extracts. The photodynamic antibacterial activity of the dye extracts is in the decreasing order of CL > HS > LI > SB while the non-photodynamic antibacterial activity is in the decreasing order of LI > CL > HS > SB. The non-photodynamic antiviral activity pattern observed is the same as that of non-photodynamic antibacterial activity observed. However, the photodynamic antiviral activity of the dye extracts is in the decreasing order of CL > LI > HS > SB. Given their performance, the dye extracts maybe mostly suitable for environmental applications including fresh produce and food disinfection, sanitation of hands and contact surfaces where water can serve as diluent for the extracts and the microenvironment is free of salts.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1179-1194"},"PeriodicalIF":3.1,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141069821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Madalena F C Silva, Rafael T Aroso, Janusz M Dabrowski, Barbara Pucelik, Agata Barzowska, Gabriela J da Silva, Luis G Arnaut, Mariette M Pereira
{"title":"Photodynamic inactivation of E. coli with cationic imidazolyl-porphyrin photosensitizers and their synergic combination with antimicrobial cinnamaldehyde.","authors":"Madalena F C Silva, Rafael T Aroso, Janusz M Dabrowski, Barbara Pucelik, Agata Barzowska, Gabriela J da Silva, Luis G Arnaut, Mariette M Pereira","doi":"10.1007/s43630-024-00581-y","DOIUrl":"10.1007/s43630-024-00581-y","url":null,"abstract":"<p><p>Bacterial infections are a global health concern, particularly due to the increasing resistance of bacteria to antibiotics. Multi-drug resistance (MDR) is a considerable challenge, and novel approaches are needed to treat bacterial infections. Photodynamic inactivation (PDI) of microorganisms is increasingly recognized as an effective method to inactivate a broad spectrum of bacteria and overcome resistance mechanisms. This study presents the synthesis of a new cationic 5,15-di-imidazolyl porphyrin derivative and the impact of n-octanol/water partition coefficient (logP) values of this class of photosensitizers on PDI efficacy of Escherichia coli. The derivative with logP = -0.5, IP-H-OH<sup>2+</sup>, achieved a remarkable 3 log CFU reduction of E. coli at 100 nM with only 1.36 J/cm<sup>2</sup> light dose at 415 nm, twice as effective as the second-best porphyrin IP-H-Me<sup>2+</sup>, of logP = -1.35. We relate the rapid uptake of IP-H-OH<sup>2+</sup> by E. coli to improved PDI and the very low uptake of a fluorinated derivative, IP-H-CF<sub>3</sub><sup>2+</sup>, logP ≈ 1, to its poor performance. Combination of PDI with cinnamaldehyde, a major component of the cinnamon plant known to alter bacteria cell membranes, offered synergic inactivation of E. coli (7 log CFU reduction), using 50 nM of IP-H-OH<sup>2+</sup> and just 1.36 J/cm<sup>2</sup> light dose. The success of combining PDI with this natural compound broadens the scope of therapies for MDR infections that do not add drug resistance. In vivo studies on a mouse model of wound infection showed the potential of cationic 5,15-di-imidazolyl porphyrins to treat clinically relevant infected wounds.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1129-1142"},"PeriodicalIF":3.1,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140908279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Linda Jernej, Danielle S M Frost, Anne-Sophie Walker, Jun Liu, Michael Fefer, Kristjan Plaetzer
{"title":"Photodynamic Inactivation in agriculture: combating fungal phytopathogens resistant to conventional treatment.","authors":"Linda Jernej, Danielle S M Frost, Anne-Sophie Walker, Jun Liu, Michael Fefer, Kristjan Plaetzer","doi":"10.1007/s43630-024-00579-6","DOIUrl":"10.1007/s43630-024-00579-6","url":null,"abstract":"<p><p>Botrytis cinerea is a severe threat in agriculture, as it can infect over 200 different crop species with gray mold affecting food yields and quality. The conventional treatment using fungicides lead to emerging resistance over the past decades. Here, we introduce Photodynamic Inactivation (PDI) as a strategy to combat B. cinerea infections, independent of fungicide resistance. PDI uses photoactive compounds, which upon illumination create reactive oxygen species toxic for killing target organisms. This study focuses on different formulations of sodium-magnesium-chlorophyllin (Chl, food additive E140) as photoactive compound in combination with EDTA disodium salt dihydrate (Na<sub>2</sub>EDTA) as cell-wall permeabilizer and a surfactant. In an in vitro experiment, three different photosensitizers (PS) with varying Chl and Na<sub>2</sub>EDTA concentrations were tested against five B. cinerea strains with different resistance mechanisms. We showed that all B. cinerea mycelial spheres of all tested strains were eradicated with concentrations as low as 224 µM Chl and 3.076 mM Na<sub>2</sub>EDTA (LED illumination with main wavelength of 395 nm, radiant exposure 106 J cm<sup>-2</sup>). To further test PDI as a Botrytis treatment strategy in agriculture a greenhouse trial was performed on B. cinerea infected bell pepper plants (Capsicum annum L). Two different rates (560 or 1120 g Ha<sup>-1</sup>) of PS formulation (0.204 M Chl and 1.279 M Na<sub>2</sub>EDTA) and a combination of PS formulation with 0.05% of the surfactant BRIJ L4 (560 g Ha<sup>-1</sup>) were applied weekly for 4 weeks by spray application. Foliar lesions, percentage of leaves affected, percentage of leaf area diseased and AUDPC were significantly reduced, while percentage of marketable plants were increased by all treatments compared to a water treated control, however, did not statistically differ from each other. No phytotoxicity was observed in any treatment. These results add to the proposition of employing PDI with the naturally sourced PS Chl in agricultural settings aimed at controlling B. cinerea disease. This approach seems to be effective regardless of the evolving resistance mechanisms observed in response to conventional antifungal treatments.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"1117-1128"},"PeriodicalIF":3.1,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140943227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gabriel F. Pelentir, Atílio Tomazini, Vanessa R. Bevilaqua, Vadim R. Viviani
{"title":"Role of Histidine 310 in Amydetes vivianii firefly luciferase pH and metal sensitivities and improvement of its color tuning properties","authors":"Gabriel F. Pelentir, Atílio Tomazini, Vanessa R. Bevilaqua, Vadim R. Viviani","doi":"10.1007/s43630-024-00570-1","DOIUrl":"https://doi.org/10.1007/s43630-024-00570-1","url":null,"abstract":"<p>Firefly luciferases emit yellow-green light and are pH-sensitive, changing the bioluminescence color to red in the presence of heavy metals, acidic pH and high temperatures. These pH and metal-sensitivities have been recently harnessed for intracellular pH indication and toxic metal biosensing. However, whereas the structure of the pH sensor and the metal binding site, which consists mainly of two salt bridges that close the active site (E311/R337 and H310/E354), has been identified, the specific role of residue H310 in pH and metal sensing is still under debate. The <i>Amydetes vivianii</i> firefly luciferase has one of the lowest pH sensitivities among the group of pH-sensitive firefly luciferases, displaying high bioluminescent activity and special spectral selectivity for cadmium and mercury, which makes it a promising analytical reagent. Using site-directed mutagenesis, we have investigated in detail the role of residue H310 on pH and metal sensitivity in this luciferase. Negatively charged residues at position 310 increase the pH sensitivity and metal sensitivity; H310G considerably increases the size of the cavity, severely impacting the activity, H310R closes the cavity, and H310F considerably decreases both pH and metal sensitivities. However, no substitution completely abolished pH and metal sensitivities. The results indicate that the presence of negatively charged and basic side chains at position 310 is important for pH sensitivity and metals coordination, but not essential, indicating that the remaining side chains of E311 and E354 may still coordinate some metals in this site. Furthermore, a metal binding site search predicted that H310 mutations decrease the affinity mainly for Zn, Ni and Hg but less for Cd, and revealed the possible existence of additional binding sites for Zn, Ni and Hg.</p><h3 data-test=\"abstract-sub-heading\">Graphical abstract</h3>\u0000","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":"6 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140839478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Spectral changes of light-harvesting complex 2 lacking B800 bacteriochlorophyll a under neutral pH conditions.","authors":"Shota Kawato, Shinichi Sato, Hirotaka Kitoh-Nishioka, Yoshitaka Saga","doi":"10.1007/s43630-024-00560-3","DOIUrl":"10.1007/s43630-024-00560-3","url":null,"abstract":"<p><p>Exchange of B800 bacteriochlorophyll (BChl) a in light-harvesting complex 2 (LH2) is promising for a better understanding of the mechanism on intracomplex excitation energy transfer of this protein. Structural and spectroscopic properties of LH2 lacking B800 BChl a (B800-depleted LH2), which is an important intermediate protein in the B800 exchange, will be useful to tackle the energy transfer mechanism in LH2 by the B800 exchange strategy. In this study, we report a unique spectral change of B800-depleted LH2, in which the Q<sub>y</sub> absorption band of B800 BChl a is automatically recovered under neutral pH conditions. This spectral change was facilitated by factors for destabilization of LH2, namely, a detergent, lauryl dimethylamine N-oxide, and an increase in temperature. Spectral analyses in the preparation of an LH2 variant denoted as B800-recovered LH2 indicated that most BChl a that was released by decomposition of part of B800-depleted LH2 was a source of the production of B800-recovered LH2. Characterization of purified B800-recovered LH2 demonstrated that its spectroscopic and structural features was quite similar to those of native LH2. The current results indicate that the recovery of the B800 Q<sub>y</sub> band of B800-depleted LH2 originates from the combination of decomposition of part of B800-depleted LH2 and in situ reconstitution of BChl a into the B800 binding pockets of residual B800-depleted LH2, resulting in the formation of stable B800-recovered LH2.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"871-879"},"PeriodicalIF":2.7,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140333965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}