eLife Sciences PublicationsActa Medica Okayama2050-084X122023Characterization of tryptophan oxidation affecting D1 degradation by FtsH in the photosystem II quality control of chloroplastsRP88822ENYusukeKatoInstitute of Plant Science and Resources (IPSR), Okayama UniversityHiroshiKurodaResearch Institute for Interdisciplinary Science, Okayama UniversityShin-IchiroOzawaInstitute of Plant Science and Resources (IPSR), Okayama UniversityKeisukeSaitoResearch Center for Advanced Science and Technology, The University of TokyoVivekDograShanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of SciencesMartinScholzInstitute of Plant Biology and Biotechnology, University of MünsterGuoxianZhangInstitute of Plant Science and Resources (IPSR), Okayama UniversityCatherinede VitryInstitut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique and Sorbonne Université Pierre et Marie CurieHiroshiIshikitaResearch Center for Advanced Science and Technology, The University of TokyoChanhongKimShanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of SciencesMichaelHipplerInstitute of Plant Science and Resources (IPSR), Okayama UniversityYuichiroTakahashiResearch Institute for Interdisciplinary Science, Okayama UniversityWataruSakamotoInstitute of Plant Science and Resources (IPSR), Okayama UniversityPhotosynthesis is one of the most important reactions for sustaining our environment. Photosystem II (PSII) is the initial site of photosynthetic electron transfer by water oxidation. Light in excess, however, causes the simultaneous production of reactive oxygen species (ROS), leading to photo-oxidative damage in PSII. To maintain photosynthetic activity, the PSII reaction center protein D1, which is the primary target of unavoidable photo-oxidative damage, is efficiently degraded by FtsH protease. In PSII subunits, photo-oxidative modifications of several amino acids such as Trp have been indeed documented, whereas the linkage between such modifications and D1 degradation remains elusive. Here, we show that an oxidative post-translational modification of Trp residue at the N-terminal tail of D1 is correlated with D1 degradation by FtsH during high-light stress. We revealed that Arabidopsis mutant lacking FtsH2 had increased levels of oxidative Trp residues in D1, among which an N-terminal Trp-14 was distinctively localized in the stromal side. Further characterization of Trp-14 using chloroplast transformation in Chlamydomonas indicated that substitution of D1 Trp-14 to Phe, mimicking Trp oxidation enhanced FtsH-mediated D1 degradation under high light, although the substitution did not affect protein stability and PSII activity. Molecular dynamics simulation of PSII implies that both Trp-14 oxidation and Phe substitution cause fluctuation of D1 N-terminal tail. Furthermore, Trp-14 to Phe modification appeared to have an additive effect in the interaction between FtsH and PSII core in vivo. Together, our results suggest that the Trp oxidation at its N-terminus of D1 may be one of the key oxidations in the PSII repair, leading to processive degradation by FtsH.No potential conflict of interest relevant to this article was reported.eLife Sciences PublicationsActa Medica Okayama2050-084X92020Altered N-glycan composition impacts flagella-mediated adhesion in Chlamydomonas reinhardtiie58805ENNannanXuKey Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of SciencesAnneOltmannsInstitute for Plant Biology and Biotechnology, University of MünsterLongshengZhaoInstitute of Integrative Biology, University of Liverpool, LiverpoolAntoineGirotMax Planck Institute for Dynamics and Self-Organization (MPIDS)MarziehKarimiMax Planck Institute for Dynamics and Self-Organization (MPIDS)LaraHoepfnerInstitute for Plant Biology and Biotechnology, University of Münsterative Biology, University of Liverpool, LiverpoolnsterSimonKelterbornInstitute of Biology, Experimental Biophysics, Humboldt University of BerlinMartinScholzInstitute for Plant Biology and Biotechnology, University of MünsterJuliaBeisselInstitute for Plant Biology and Biotechnology, University of MünsterPeterHegemannInstitute of Biology, Experimental Biophysics, Humboldt University of BerlinOliverBaeumchenMax Planck Institute for Dynamics and Self-Organization (MPIDS)Lu-NingLiuInstitute of Integrative Biology, University of Liverpool, LiverpoolKaiyaoHuangKey Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of SciencesMichaelHipplerInstitute of Plant Science and Resources, Okayama UniversityFor the unicellular alga Chlamydomonas reinhardtii, the presence of N-glycosylated proteins on the surface of two flagella is crucial for both cell-cell interaction during mating and flagellar surface adhesion. However, it is not known whether only the presence or also the composition of N-glycans attached to respective proteins is important for these processes. To this end, we tested several C. reinhardtii insertional mutants and a CRISPR/Cas9 knockout mutant of xylosyltransferase 1A, all possessing altered N-glycan compositions. Taking advantage of atomic force microscopy and micropipette force measurements, our data revealed that reduction in N-glycan complexity impedes the adhesion force required for binding the flagella to surfaces. This results in impaired polystyrene bead binding and transport but not gliding of cells on solid surfaces. Notably, assembly, intraflagellar transport, and protein import into flagella are not affected by altered N-glycosylation. Thus, we conclude that proper N-glycosylation of flagellar proteins is crucial for adhering C. reinhardtii cells onto surfaces, indicating that N-glycans mediate surface adhesion via direct surface contact.No potential conflict of interest relevant to this article was reported.eLife Sciences PublicationsActa Medica Okayama2050-084X92020Genetic profiling of protein burden and nuclear export overloade54080ENReikoKintakaDonnelly Center for Cellular and Biomolecular Research, Department of Medical Genetics, University of TorontoKojiMakanaeResearch Core for Interdisciplinary Sciences, Okayama UniversityShotaroNambaMatching Program Course, Okayama UniversityHisaakiKatoSchool of Environmental and Life Science, Okayama UniversityKeijiKitoDepartment of Life Sciences, School of Agriculture, Meiji UniversityShinsukeOhnukiGraduate School of Frontier Sciences, University of TokyoYoshikazuOhyaGraduate School of Frontier Sciences, University of TokyoBrenda J.AndrewsDonnelly Center for Cellular and Biomolecular Research, Department of Medical Genetics, University of TorontoCharlesBooneDonnelly Center for Cellular and Biomolecular Research, Department of Medical Genetics, University of TorontoHisaoMoriyaResearch Core for Interdisciplinary Sciences, Okayama UniversityOverproduction (op) of proteins triggers cellular defects. One of the consequences of overproduction is the protein burden/cost, which is produced by an overloading of the protein synthesis process. However, the physiology of cells under a protein burden is not well characterized. We performed genetic profiling of protein burden by systematic analysis of genetic interactions between GFP-op, surveying both deletion and temperature-sensitive mutants in budding yeast. We also performed genetic profiling in cells with overproduction of triple-GFP (tGFP), and the nuclear export signal-containing tGFP (NES-tGFP). The mutants specifically interacted with GFP-op were suggestive of unexpected connections between actin-related processes like polarization and the protein burden, which was supported by morphological analysis. The tGFP-op interactions suggested that this protein probe overloads the proteasome, whereas those that interacted with NES-tGFP involved genes encoding components of the nuclear export process, providing a resource for further analysis of the protein burden and nuclear export overload.No potential conflict of interest relevant to this article was reported.eLife Sciences PublicationsActa Medica Okayama2050-084X72018Metabolic co-dependence drives the evolutionarily ancient Hydra-Chlorella symbiosise35122ENMayukoHamadaUshimado Marine Institute, Okayama UniversityKatjaSchröder Interdisciplinary Research Center, Kiel Life Science, Kiel UniversityJayBathia Interdisciplinary Research Center, Kiel Life Science, Kiel UniversityUlrichKürn Interdisciplinary Research Center, Kiel Life Science, Kiel UniversitySebastianFraune Interdisciplinary Research Center, Kiel Life Science, Kiel UniversityMariiaKhalturinaMarine Genomics Unit, Okinawa Institute of Science and Technology Graduate UniversityKonstantinKhalturinMarine Genomics Unit, Okinawa Institute of Science and Technology Graduate UniversityChuyaShinzatoMarine Genomics Unit, Okinawa Institute of Science and Technology Graduate UniversityNoriSatohMarine Genomics Unit, Okinawa Institute of Science and Technology Graduate UniversityThomas CGBosch Interdisciplinary Research Center, Kiel Life Science, Kiel University Many multicellular organisms rely on symbiotic associations for support of metabolic activity, protection, or energy. Understanding the mechanisms involved in controlling such interactions remains a major challenge. In an unbiased approach we identified key players that control the symbiosis between Hydra viridissima and its photosynthetic symbiont Chlorella sp. A99. We discovered significant up-regulation of Hydra genes encoding a phosphate transporter and glutamine synthetase suggesting regulated nutrition supply between host and symbionts. Interestingly, supplementing the medium with glutamine temporarily supports in vitro growth of the otherwise obligate symbiotic Chlorella, indicating loss of autonomy and dependence on the host. Genome sequencing of Chlorella sp. A99 revealed a large number of amino acid transporters and a degenerated nitrate assimilation pathway, presumably as consequence of the adaptation to the host environment. Our observations portray ancient symbiotic interactions as a codependent partnership in which exchange of nutrients appears to be the primary driving force.No potential conflict of interest relevant to this article was reported.eLife Sciences PublicationsActa Medica Okayama2050-084X72018Dynamic clustering of dynamin-amphiphysin helices regulates membrane constriction and fission coupled with GTP hydrolysise30246ENTetsuyaTakedaGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityToshiyaKozaiDepartment of Physics, College of Science and Engineering, Kanazawa UniversityHuiranYangGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityDaikiIshikuroDepartment of Physics, College of Science and Engineering, Kanazawa UniversityKahoSeyamaGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityYusukeKumagaiDepartment of Physics, College of Science and Engineering, Kanazawa UniversityTadashiAbeGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityHiroshiYamadaGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama UniversityTakayukiUchihashiCREST, JSTToshioAndoCREST, JSTKohjiTakeiGraduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University Dynamin is a mechanochemical GTPase essential for membrane fission during clathrin-mediated endocytosis. Dynamin forms helical complexes at the neck of clathrin-coated pits and their structural changes coupled with GTP hydrolysis drive membrane fission. Dynamin and its binding protein amphiphysin cooperatively regulate membrane remodeling during the fission, but its precise mechanism remains elusive. In this study, we analyzed structural changes of dynamin-amphiphysin complexes during the membrane fission using electron microscopy (EM) and high-speed atomic force microscopy (HS-AFM). Interestingly, HS-AFM analyses show that the dynamin-amphiphysin helices are rearranged to form clusters upon GTP hydrolysis and membrane constriction occurs at protein-uncoated regions flanking the clusters. We also show a novel function of amphiphysin in size control of the clusters to enhance biogenesis of endocytic vesicles. Our approaches using combination of EM and HS-AFM clearly demonstrate new mechanistic insights into the dynamics of dynamin-amphiphysin complexes during membrane fission.No potential conflict of interest relevant to this article was reported.