biostudies-literatureAdler LGerman Research FoundationLeverhulme TrustDFGBill & Melinda Gates Agricultural InnovationsCarl Tryggers FoundationSwedish Research CouncilCarnegie Institution for ScienceUniversity of York Biosciences Technology FacilityBBSRC Discovery FellowshipEngineering and Physical Research CouncilDeutsche ForschungsgemeinschaftUnited Kingdom Research and Innovation Future Leaders FellowshipEASTBIO DTPBill & Melinda Gates Agricultural InnovationsWellcome TrustBiotechnology and Biological Sciences Research Council2374-2394https://www.ebi.ac.uk/biostudies/studies/S-EPMC11638005biostudies-literatureUnknown196(4)In many eukaryotic algae, CO2 fixation by Rubisco is enhanced by a CO2-concentrating mechanism, which utilizes a Rubisco-rich organelle called the pyrenoid. The pyrenoid is traversed by a network of thylakoid membranes called pyrenoid tubules, which are proposed to deliver CO2. In the model alga Chlamydomonas (Chlamydomonas reinhardtii), the pyrenoid tubules have been proposed to be tethered to the Rubisco matrix by a bestrophin-like transmembrane protein, BST4. Here, we show that BST4 forms a complex that localizes to the pyrenoid tubules. A Chlamydomonas mutant impaired in the accumulation of BST4 (bst4) formed normal pyrenoid tubules, and heterologous expression of BST4 in Arabidopsis (Arabidopsis thaliana) did not lead to the incorporation of thylakoids into a reconstituted Rubisco conPlant physiologyBestrophin-like protein 4 is involved in photosynthetic acclimation to light fluctuations in Chlamydomonas.PMC11638005BB/R001014/1BB/J01446X/12021-03790BB/S015337/1BB/W009587/1BB/P011586/1BB/Y000323/1VR 2016-03836BB/S015531/1EP/W024063/153197RPG-2017-402BB/T013508/1456013262BB/T017589/1CTS 20:406MR/T020679/1WT104915MABlatt MRWalker CEPayne-Dwyer ALPeltier GEmrich-Mills TZMackinder LCMLau CSSpetea CShaikh KMAtkinson NLeake MCGirr PMcCormick AJAdler Lvan Maldegem KADukic EBarrett JLefoulon CBurlacot AfalseBestrophin-like protein 4 is involved in photosynthetic acclimation to light fluctuations in Chlamydomonas.In many eukaryotic algae, CO2 fixation by Rubisco is enhanced by a CO2-concentrating mechanism, which utilizes a Rubisco-rich organelle called the pyrenoid. The pyrenoid is traversed by a network of thylakoid membranes called pyrenoid tubules, which are proposed to deliver CO2. In the model alga Chlamydomonas (Chlamydomonas reinhardtii), the pyrenoid tubules have been proposed to be tethered to the Rubisco matrix by a bestrophin-like transmembrane protein, BST4. Here, we show that BST4 forms a complex that localizes to the pyrenoid tubules. A Chlamydomonas mutant impaired in the accumulation of BST4 (bst4) formed normal pyrenoid tubules, and heterologous expression of BST4 in Arabidopsis (Arabidopsis thaliana) did not lead to the incorporation of thylakoids into a reconstituted Rubisco con2024-01-01T00:00:00Z2024 Dec2026-04-22T03:15:09.819Z2025-04-04T00:36:51.792ZS-EPMC116380053924072410.1093/plphys/kiae450