Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(16/16) Fantastic collaboration with @james-r-barrett.bsky.social, @jesshpritchard.bsky.social, @phaips.vd.st, @manondemulder.bsky.social,Tommaso, @mariahondele.bsky.social, @cellarchlab.com, @mccormicklab.bsky.social and @mackinderlab.bsky.social 040
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(15/16) Together, these findings provide the first structural and molecular model of the Chlorella pyrenoid, and hand plant engineers new, simpler parts for building a synthetic CO2-concentrating pyrenoid in crops. 121
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(14/16) Expressed in a plant (Nicotiana benthamiana), these Chlorella proteins localized correctly to starch or membranes — an encouraging sign for engineering active pyrenoid into crop chloroplasts. 121
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(13/16) PMTT has a membrane-anchoring domain, binds thylakoid-specific lipids, and sits at the interface where membranes meet the Rubisco droplet — suggesting it tethers CO2-delivering membranes to the pyrenoid. 120
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(12/16) PMST carries a starch-binding domain and tethers the droplets to starch granules — likely helping build the starch shell that surrounds the pyrenoid and helps trap CO2 inside. 120
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(11/16) All three proteins can trigger Rubisco to condense into droplets in vitro. But at natural (in vivo) concentrations, only CsLinker is abundant enough to drive this alone — the new proteins instead get recruited into CsLinker-Rubisco droplets. 111
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(10/16) We found three new pyrenoid proteins — PMTT, RHOP and PMST — by searching for a Rubisco-binding motif shared with the known linker protein CsLinker. All three bind Rubisco directly, confirmed by co-immunoprecipitation. 121
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(9/16) Using cryo-electron tomography #TeamTomo, we revealed the native 3D architecture of the Chlorella pyrenoid at molecular resolution — the Rubisco matrix is bisected by two specialized thylakoids that contain dense protein arrays and deliver CO2 to Rubisco. 141
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(8/16) Comparing proteomes of Chlorella and Chlamydomonas: the CO2/bicarbonate transport machinery is largely conserved between the two, but the structural proteins that build the pyrenoid itself are completely different — direct evidence of convergent evolution. 140
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(7/16) We turned to Chlorella sorokiniana, a fast-growing alga with a simpler, distinct pyrenoid. We confirmed it has an inducible CCM: low CO2 triggers pyrenoid formation and boosts the cell's affinity for inorganic carbon, just like Chlamydomonas. 141
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(6/16) Our recent review on the evolution of pyrenoid can be found here: doi.org/10.1146/annu...doi.orgPyrenoid Structure, Function, Evolution, and Characterization Across Diverse LineagesPyrenoids are eukaryotic CO2-fixing organelles that are evolutionarily diverse, globally abundant, and critical to global carbon cycling. Despite being described over 200 years ago, the vast majority ... 131
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(5/16) The problem: almost everything we know about pyrenoids comes from one alga, Chlamydomonas. But pyrenoids evolved independently multiple times across algae (convergent evolution), so we can't assume other algae build theirs the same way. 111
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(4/16) Why care? Crops like rice, wheat and soy lack a pyrenoid-based CO2-concentrating mechanism (CCM). Engineering one into these C3 crops could improve photosynthesis, yield, and water/nitrogen-use efficiency 131
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(3/16) What is a pyrenoid? It is a droplet-like compartment inside the chloroplast that packs Rubisco (the enzyme that fixes CO2) together with a CO2 delivery system, raising local CO2 around Rubisco and making carbon fixation faster and more efficient. 162
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(2/16)Pre print here: www.biorxiv.org/content/10.6...biorxiv.orgMolecular organization of the Chlorella sorokiniana pyrenoidTo overcome the enzymatic limitations of Rubisco, algae operate CO2-concentrating mechanisms (CCMs) that deliver concentrated CO2 to Rubisco tightly packaged in a specialized microcompartment called a... 121
Mihris Naduthodi @mihrisn.bsky.social · 22/07/2026(1/16) Nearly two-thirds of ocean carbon fixation flows through a diverse organelle: the pyrenoid. Our new paper maps its 3D architecture in the alga Chlorella and identifies new proteins — expanding the toolkit to engineer this CO2-concentrating machine into crops🧵 #Pyrenoid #CCM #Photosynthesis 13418
