start-ver=1.4 cd-journal=joma no-vol=8 cd-vols= no-issue= article-no= start-page=431 end-page=443 dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=202105 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Capturing structural changes of the S-1 to S-2 transition of photosystem II using time-resolved serial femtosecond crystallography en-subtitle= kn-subtitle= en-abstract= kn-abstract=Photosystem II (PSII) catalyzes light-induced water oxidation through an S-i-state cycle, leading to the generation of di-oxygen, protons and electrons. Pumpprobe time-resolved serial femtosecond crystallography (TR-SFX) has been used to capture structural dynamics of light-sensitive proteins. In this approach, it is crucial to avoid light contamination in the samples when analyzing a particular reaction intermediate. Here, a method for determining a condition that avoids light contamination of the PSII microcrystals while minimizing sample consumption in TR-SFX is described. By swapping the pump and probe pulses with a very short delay between them, the structural changes that occur during the S-1-to-S-2 transition were examined and a boundary of the excitation region was accurately determined. With the sample flow rate and concomitant illumination conditions determined, the S-2-state structure of PSII could be analyzed at room temperature, revealing the structural changes that occur during the S-1-to-S-2 transition at ambient temperature. Though the structure of the manganese cluster was similar to previous studies, the behaviors of the water molecules in the two channels (O1 and O4 channels) were found to be different. By comparing with the previous studies performed at low temperature or with a different delay time, the possible channels for water inlet and structural changes important for the water-splitting reaction were revealed. en-copyright= kn-copyright= en-aut-name=LiHongjie en-aut-sei=Li en-aut-mei=Hongjie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=NakajimaYoshiki en-aut-sei=Nakajima en-aut-mei=Yoshiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NomuraTakashi en-aut-sei=Nomura en-aut-mei=Takashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SugaharaMichihiro en-aut-sei=Sugahara en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=YonekuraShinichiro en-aut-sei=Yonekura en-aut-mei=Shinichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=ChanSiu Kit en-aut-sei=Chan en-aut-mei=Siu Kit kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= en-aut-name=NakaneTakanori en-aut-sei=Nakane en-aut-mei=Takanori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=7 ORCID= en-aut-name=YamaneTakahiro en-aut-sei=Yamane en-aut-mei=Takahiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=8 ORCID= en-aut-name=UmenaYasufumi en-aut-sei=Umena en-aut-mei=Yasufumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=9 ORCID= en-aut-name=SuzukiMamoru en-aut-sei=Suzuki en-aut-mei=Mamoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=10 ORCID= en-aut-name=MasudaTetsuya en-aut-sei=Masuda en-aut-mei=Tetsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=11 ORCID= en-aut-name=MotomuraTaiki en-aut-sei=Motomura en-aut-mei=Taiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=12 ORCID= en-aut-name=NaitowHisashi en-aut-sei=Naitow en-aut-mei=Hisashi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=13 ORCID= en-aut-name=MatsuuraYoshinori en-aut-sei=Matsuura en-aut-mei=Yoshinori kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=14 ORCID= en-aut-name=KimuraTetsunari en-aut-sei=Kimura en-aut-mei=Tetsunari kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=15 ORCID= en-aut-name=TonoKensuke en-aut-sei=Tono en-aut-mei=Kensuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=16 ORCID= en-aut-name=OwadaShigeki en-aut-sei=Owada en-aut-mei=Shigeki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=17 ORCID= en-aut-name=JotiYasumasa en-aut-sei=Joti en-aut-mei=Yasumasa kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=18 ORCID= en-aut-name=TanakaRie en-aut-sei=Tanaka en-aut-mei=Rie kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=19 ORCID= en-aut-name=NangoEriko en-aut-sei=Nango en-aut-mei=Eriko kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=20 ORCID= en-aut-name=AkitaFusamichi en-aut-sei=Akita en-aut-mei=Fusamichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=21 ORCID= en-aut-name=KuboMinoru en-aut-sei=Kubo en-aut-mei=Minoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=22 ORCID= en-aut-name=IwataSo en-aut-sei=Iwata en-aut-mei=So kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=23 ORCID= en-aut-name=ShenJian-Ren en-aut-sei=Shen en-aut-mei=Jian-Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=24 ORCID= en-aut-name=SugaMichihiro en-aut-sei=Suga en-aut-mei=Michihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=25 ORCID= affil-num=1 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Life Science, University of Hyogo kn-affil= affil-num=4 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=5 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=6 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=7 en-affil=Department of Biological Science, Graduate School of Science, The University of Tokyo kn-affil= affil-num=8 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=9 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=10 en-affil=Institute for Protein Research, Osaka University kn-affil= affil-num=11 en-affil=Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University kn-affil= affil-num=12 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=13 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=14 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=15 en-affil=Department of Chemistry, Graduate School of Science, Kobe University kn-affil= affil-num=16 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=17 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=18 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=19 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=20 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=21 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=22 en-affil=Graduate School of Life Science, University of Hyogo kn-affil= affil-num=23 en-affil=RIKEN SPring-8 Center kn-affil= affil-num=24 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=25 en-affil=Research Institute for Interdisciplinary Science and Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=time-resolved serial crystallography kn-keyword=time-resolved serial crystallography en-keyword=X-ray free-electron lasers kn-keyword=X-ray free-electron lasers en-keyword=membrane proteins kn-keyword=membrane proteins en-keyword=photosystem II kn-keyword=photosystem II en-keyword=serial crystallography kn-keyword=serial crystallography en-keyword=molecular movies kn-keyword=molecular movies en-keyword=protein structures kn-keyword=protein structures END