{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T01:47:16Z","timestamp":1792028836861,"version":"4.4.0"},"reference-count":52,"publisher":"National Academy of Sciences","issue":"36","license":[{"start":{"date-parts":[[2025,9,5]],"date-time":"2025-09-05T00:00:00Z","timestamp":1757030400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/100006151","name":"DOE | SC | Basic Energy Sciences","doi-asserted-by":"publisher","award":["DE-FG02-08ER15968"],"award-info":[{"award-number":["DE-FG02-08ER15968"]}],"id":[{"id":"10.13039\/100006151","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100006151","name":"DOE | SC | Basic Energy Sciences","doi-asserted-by":"publisher","award":["DE-SC0024643"],"award-info":[{"award-number":["DE-SC0024643"]}],"id":[{"id":"10.13039\/100006151","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2025,9,9]]},"abstract":"<jats:p>\n                    Cyanobacteria achieve highly efficient photosynthesis using a CO\n                    <jats:sub>2<\/jats:sub>\n                    -concentrating mechanism relying on specialized Type I (NDH-1) complexes. Among these, NDH-1\n                    <jats:sub>3<\/jats:sub>\n                    and NDH-1\n                    <jats:sub>4<\/jats:sub>\n                    catalyze redox-coupled hydration of CO\n                    <jats:sub>2<\/jats:sub>\n                    to bicarbonate, supporting carbon fixation in carboxysomes. The mechanism of coupling electron transfer to CO\n                    <jats:sub>2<\/jats:sub>\n                    -hydration by these variant NDH-1 complexes remains unknown. We engineered a\n                    <jats:italic toggle=\"yes\">Synechococcus<\/jats:italic>\n                    PCC7942 strain that expresses exclusively the high flux\/low affinity NDH-1\n                    <jats:sub>4<\/jats:sub>\n                    complex, enabling the observation of the coupling of CO\n                    <jats:sub>2<\/jats:sub>\n                    hydration to cyclic electron flow in isolation from the other NDH-1 isoforms normally present in cells. We found that inhibition of the CupB protein by the carbonic anhydrase inhibitor ethoxzolamide (EZ) suppressed CO\n                    <jats:sub>2<\/jats:sub>\n                    uptake, slowed photosystem I rereduction, and abolished proton pumping as probed by acridine orange fluorescence. These effects were absent in strains lacking Cup proteins, confirming specificity. The results demonstrate that CO\n                    <jats:sub>2<\/jats:sub>\n                    hydration and electron transfer through NDH-1\n                    <jats:sub>4<\/jats:sub>\n                    are tightly coupled via proton translocation across the thylakoid membrane. These findings provide direct evidence for the bidirectional interaction in bioenergetic coupling between the plastoquinone reduction and the CO\n                    <jats:sub>2<\/jats:sub>\n                    uptake at the distal Zn-site over a span of ~150 \u00c5 and support a proton-removal hypothesis involving the proton transfer pathways from the Zn-site of CO\n                    <jats:sub>2<\/jats:sub>\n                    hydration to an energetically coupled proton loading site evolutionarily repurposed from the ancestral proton pumping mechanism to enable energetic CO\n                    <jats:sub>2<\/jats:sub>\n                    uptake.\n                  <\/jats:p>","DOI":"10.1073\/pnas.2511786122","type":"journal-article","created":{"date-parts":[[2025,9,5]],"date-time":"2025-09-05T17:41:21Z","timestamp":1757094081000},"update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":13,"title":["Action at a distance: The remarkable coupling of CO\n                    <sub>2<\/sub>\n                    uptake to electron transfer in specialized cyanobacterial NDH-1 complexes"],"prefix":"10.1073","volume":"122","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8179-3510","authenticated-orcid":false,"given":"Zhifen","family":"Zhang","sequence":"first","affiliation":[{"name":"Department of Microbiology and Molecular Genetics, Oklahoma State University","place":["Stillwater"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Minquan","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Molecular Genetics, Oklahoma State University","place":["Stillwater"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6715-5961","authenticated-orcid":false,"given":"Robert L.","family":"Burnap","sequence":"additional","affiliation":[{"name":"Department of Microbiology and Molecular Genetics, Oklahoma State University","place":["Stillwater"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2025,9,5]]},"reference":[{"key":"e_1_3_4_1_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.sbi.2022.102350"},{"key":"e_1_3_4_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jbc.2021.100740"},{"key":"e_1_3_4_3_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-021-04277-6"},{"key":"e_1_3_4_4_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-biochem-070511-103700"},{"key":"e_1_3_4_5_2","doi-asserted-by":"publisher","DOI":"10.1021\/acs.accounts.1c00524"},{"key":"e_1_3_4_6_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.191258298"},{"key":"e_1_3_4_7_2","doi-asserted-by":"publisher","DOI":"10.1128\/JB.182.9.2591-2596.2000"},{"key":"e_1_3_4_8_2","doi-asserted-by":"publisher","DOI":"10.1074\/jbc.M003706200"},{"key":"e_1_3_4_9_2","doi-asserted-by":"publisher","DOI":"10.1105\/tpc.104.026526"},{"key":"e_1_3_4_10_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1365-2958.1999.01457.x"},{"key":"e_1_3_4_11_2","doi-asserted-by":"publisher","DOI":"10.1007\/BF00384557"},{"key":"e_1_3_4_12_2","doi-asserted-by":"publisher","DOI":"10.1071\/PP01213"},{"key":"e_1_3_4_13_2","first-page":"348","article-title":"Regulation of CO2 concentrating mechanism in cyanobacteria","volume":"5","author":"Burnap R. 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