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Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2026,2,10]]},"abstract":"<jats:p>\n                    Microalgae induce a CO\n                    <jats:sub>2<\/jats:sub>\n                    -concentrating mechanism (CCM) to maintain photosynthesis when CO\n                    <jats:sub>2<\/jats:sub>\n                    is limited. Because this system consumes a substantial portion of photosynthetically generated ATP, its suppression when CO\n                    <jats:sub>2<\/jats:sub>\n                    levels rise is critical for energy balance, yet the underlying mechanism remains unclear. Here, we identify a nuclear repressor of the CCM in the green alga\n                    <jats:italic toggle=\"yes\">Chlamydomonas reinhardtii<\/jats:italic>\n                    . A pull-down screen for interacting partners of the master activator CCM1\/CIA5 revealed an uncharacterized protein that tightly associates with CCM1. This protein, CCM1-binding protein 1 (CBP1), combines a CobW\/CobW_C GTP-binding metallochaperone module with a WW-domain characteristic of protein\u2013protein interactions. CBP1 colocalizes and interacts with CCM1 in the nucleus regardless of CO\n                    <jats:sub>2<\/jats:sub>\n                    conditions. Disruption of CBP1 does not affect growth or CCM induction under CO\n                    <jats:sub>2<\/jats:sub>\n                    limitation but derepresses 27 of 41 CCM1-dependent low-CO\n                    <jats:sub>2<\/jats:sub>\n                    inducible genes under high-CO\n                    <jats:sub>2<\/jats:sub>\n                    conditions. These include the periplasmic and intracellular carbonic anhydrases (CAH1 and LCIB) and inorganic carbon transporters\/channels (LCIA, LCI1, BST1, and BST3). Consistently,\n                    <jats:italic toggle=\"yes\">cbp1<\/jats:italic>\n                    mutants accumulate CAH1 and LCIB proteins and exhibit 40% higher inorganic carbon affinity under high-CO\n                    <jats:sub>2<\/jats:sub>\n                    conditions; this phenotype is rescued by CBP1 complementation or by acetazolamide treatment. Crucially,\n                    <jats:italic toggle=\"yes\">cbp1<\/jats:italic>\n                    mutants exhibit significant growth delays under high-CO\n                    <jats:sub>2<\/jats:sub>\n                    conditions, especially when light is limiting, providing direct evidence that CBP1-mediated repression is essential for energy conservation. Thus, CBP1 prevents unnecessary CCM activity when CO\n                    <jats:sub>2<\/jats:sub>\n                    is abundant, acting upstream of both transporter\/channel and carbonic anhydrase modules. Our findings suggest a regulatory mechanism potentially linking zinc-dependent protein chemistry to CCM gene repression, providing insights into energy-efficient CO\n                    <jats:sub>2<\/jats:sub>\n                    sensing in aquatic photosynthetic organisms.\n                  <\/jats:p>","DOI":"10.1073\/pnas.2518136123","type":"journal-article","created":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T18:40:13Z","timestamp":1770230413000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":5,"title":["A nuclear CobW\/WW-domain factor represses the CO\n                    <sub>2<\/sub>\n                    -concentrating mechanism in the green alga\n                    <i>Chlamydomonas reinhardtii<\/i>"],"prefix":"10.1073","volume":"123","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7577-2783","authenticated-orcid":false,"given":"Daisuke","family":"Shimamura","sequence":"first","affiliation":[{"name":"Graduate School of Biostudies, Division of Integrated Life Science, Kyoto University","place":["Kyoto, Japan"]},{"name":"RIKEN Center for Sustainable Resource Science","place":["Yokohama, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0000-0654-8876","authenticated-orcid":false,"given":"Junko","family":"Yasuda","sequence":"additional","affiliation":[{"name":"Graduate School of Biostudies, Division of Integrated Life Science, Kyoto University","place":["Kyoto, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yosuke","family":"Yamahara","sequence":"additional","affiliation":[{"name":"Graduate School of Biostudies, Division of Integrated Life Science, Kyoto University","place":["Kyoto, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hirobumi","family":"Nakano","sequence":"additional","affiliation":[{"name":"Graduate School of Biostudies, Division of Integrated Life Science, Kyoto University","place":["Kyoto, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7698-5350","authenticated-orcid":false,"given":"Shin-Ichiro","family":"Ozawa","sequence":"additional","affiliation":[{"name":"Institute of Plant Science and Resources, Okayama University","place":["Kurashiki, Japan"]},{"name":"Research Institute for Interdisciplinary Science, Okayama University","place":["Okayama, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryutaro","family":"Tokutsu","sequence":"additional","affiliation":[{"name":"Graduate School of Science, Division of Biological Sciences, Kyoto University","place":["Kyoto, Japan"]},{"name":"School of Veterinary Medicine, Kitasato University","place":["Sagamihara, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4222-4769","authenticated-orcid":false,"given":"Ayumi","family":"Yamagami","sequence":"additional","affiliation":[{"name":"Graduate School of Biostudies, Division of Integrated Life Science, Kyoto University","place":["Kyoto, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7735-8567","authenticated-orcid":false,"given":"Tomonao","family":"Matsushita","sequence":"additional","affiliation":[{"name":"Graduate School of Science, Division of Biological Sciences, Kyoto University","place":["Kyoto, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6410-0447","authenticated-orcid":false,"given":"Yuichiro","family":"Takahashi","sequence":"additional","affiliation":[{"name":"Research Institute for Interdisciplinary Science, Okayama University","place":["Okayama, 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Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6578-8095","authenticated-orcid":false,"given":"Takashi","family":"Yamano","sequence":"additional","affiliation":[{"name":"Graduate School of Biostudies, Division of Integrated Life Science, Kyoto University","place":["Kyoto, Japan"]},{"name":"Center for Living Systems Information Science, Kyoto University","place":["Kyoto, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2026,2,4]]},"reference":[{"key":"e_1_3_4_1_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature01843"},{"key":"e_1_3_4_2_2","doi-asserted-by":"publisher","DOI":"10.1126\/sciadv.abq6161"},{"key":"e_1_3_4_3_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.arplant.56.032604.144052"},{"key":"e_1_3_4_4_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-marine-120709-142720"},{"key":"e_1_3_4_5_2","doi-asserted-by":"publisher","DOI":"10.1093\/jxb\/erx110"},{"key":"e_1_3_4_6_2","doi-asserted-by":"publisher","DOI":"10.1104\/pp.104.041400"},{"key":"e_1_3_4_7_2","doi-asserted-by":"publisher","DOI":"10.1105\/tpc.021162"},{"key":"e_1_3_4_8_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.081593498"},{"key":"e_1_3_4_9_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.101534498"},{"key":"e_1_3_4_10_2","doi-asserted-by":"publisher","DOI":"10.1105\/tpc.111.093435"},{"key":"e_1_3_4_11_2","doi-asserted-by":"publisher","DOI":"10.1105\/tpc.112.097949"},{"key":"e_1_3_4_12_2","doi-asserted-by":"publisher","DOI":"10.1105\/tpc.114.124537"},{"key":"e_1_3_4_13_2","doi-asserted-by":"publisher","DOI":"10.1093\/pcp\/pcn003"},{"key":"e_1_3_4_14_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.algal.2017.03.006"},{"key":"e_1_3_4_15_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2958.2001.02239.x"},{"key":"e_1_3_4_16_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-2958.2004.04021.x"},{"key":"e_1_3_4_17_2","doi-asserted-by":"publisher","DOI":"10.1104\/pp.111.190249"},{"key":"e_1_3_4_18_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-022-04662-9"},{"key":"e_1_3_4_19_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41477-022-01153-7"},{"key":"e_1_3_4_20_2","first-page":"824","article-title":"Energetics 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Burlacot, R. Shingles, Energetics of the CO2-concentrating mechanism in algae. Trends Plant Sci. 28, 824\u2013837 (2023).","journal-title":"Trends Plant Sci."},{"key":"e_1_3_4_21_2","doi-asserted-by":"publisher","DOI":"10.1093\/mtomcs\/mfab046"},{"key":"e_1_3_4_22_2","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2164-10-470"},{"key":"e_1_3_4_23_2","doi-asserted-by":"publisher","DOI":"10.3389\/fpls.2023.1237722"},{"key":"e_1_3_4_24_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1004788107"},{"key":"e_1_3_4_25_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41477-021-00856-7"},{"key":"e_1_3_4_26_2","doi-asserted-by":"publisher","DOI":"10.1007\/s11120-022-00996-7"},{"key":"e_1_3_4_27_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-023-44492-5"},{"key":"e_1_3_4_28_2","doi-asserted-by":"publisher","DOI":"10.1093\/plphys\/kiae463"},{"key":"e_1_3_4_29_2","doi-asserted-by":"publisher","DOI":"10.1104\/pp.114.248294"},{"key":"e_1_3_4_30_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.cell.2017.08.044"},{"key":"e_1_3_4_31_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ygeno.2019.06.027"},{"key":"e_1_3_4_32_2","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0100343"},{"key":"e_1_3_4_33_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.celrep.2022.110834"},{"key":"e_1_3_4_34_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.cell.2022.04.011"},{"key":"e_1_3_4_35_2","doi-asserted-by":"publisher","DOI":"10.3390\/biology6010011"},{"key":"e_1_3_4_36_2","doi-asserted-by":"publisher","DOI":"10.1016\/0167-4838(92)90235-6"},{"key":"e_1_3_4_37_2","doi-asserted-by":"publisher","DOI":"10.1093\/plphys\/kiab528"},{"key":"e_1_3_4_38_2","doi-asserted-by":"publisher","DOI":"10.1105\/tpc.108.063313"},{"key":"e_1_3_4_39_2","doi-asserted-by":"publisher","DOI":"10.1093\/bib\/bbx108"},{"key":"e_1_3_4_40_2","doi-asserted-by":"publisher","DOI":"10.1093\/molbev\/msy096"},{"key":"e_1_3_4_41_2","doi-asserted-by":"publisher","DOI":"10.1111\/tpj.17212"},{"key":"e_1_3_4_42_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jbiosc.2012.12.020"},{"key":"e_1_3_4_43_2","doi-asserted-by":"publisher","DOI":"10.1104\/pp.107.114652"},{"key":"e_1_3_4_44_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/gky354"},{"key":"e_1_3_4_45_2","doi-asserted-by":"publisher","DOI":"10.2323\/jgam.2022.08.001"},{"key":"e_1_3_4_46_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1501659112"},{"key":"e_1_3_4_47_2","doi-asserted-by":"publisher","DOI":"10.1105\/tpc.109.071811"},{"key":"e_1_3_4_48_2","doi-asserted-by":"publisher","DOI":"10.1093\/pcp\/pcq105"},{"key":"e_1_3_4_49_2","doi-asserted-by":"publisher","DOI":"10.1271\/bbb.56.794"},{"key":"e_1_3_4_50_2","unstructured":"D. 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