"Molecular analyses revealed that the Ad1/Pmp1 protein is encoded by LciB, a gene previously identified as a CO(2)-responsive gene."

"we identified and characterized a pmp1 allelic mutant, air dier 1 (ad1) that, like pmp1, cannot grow in low CO(2) (350 ppm) but can grow either in high CO(2) (5% CO(2)) or in very low CO(2) (<200 ppm)."

"LciB and three related genes in C. reinhardtii compose a unique gene family that encode four closely related, apparently soluble plastid proteins with no clearly identifiable conserved motifs."

"we provide evidence to demonstrate that LCIB interacts with the LCIB homologous protein LCIC in yeast and in vivo."

"We also show that LCIB and LCIC are co-localized in the vicinity of the pyrenoid under LC conditions in the light, forming a hexamer complex of approximately 350 kDa, as estimated by gel filtration chromatography."

"In contrast, in the dark or under high-CO2 conditions when the CCM was inactive, LCIB immediately diffused away from the pyrenoid."

"We determined the crystal structures of LCIB and limiting CO2-inducible C protein (LCIC) from C. reinhardtii and a CA-functional homolog from Phaeodactylum tricornutum, all of which harbor motifs bearing close resemblance to the active site of canonical β-CAs."

"Three of the six homologs are functional carbonic anhydrases (CAs)."

"Although both LCIB and LCIC are structurally similar to βCAs, their CA activity has not been demonstrated to date."

"We provide evidence that LCIB is an active CA using a Saccharomyces cerevisiae CA knockout mutant (∆NCE103) and an Arabidopsis thaliana βCA5 knockout mutant (βca5)."

"We show that different truncated versions of the LCIB protein complement ∆NCE103, while the full length LCIB protein complements βca5 plants, so that both the yeast and plant mutants can grow in low CO2 conditions."

"LCIB was exclusively localized in the stroma and remained biologically active, leading to a ~3-fold increase in total carbonic anhydrase activity and a lower apparent CO2 compensation point (-10%)."

"Leaf extracts from LB-3 and LB-6 lines showed significantly higher total carbonic anhydrase activity than wild-type and vector controls."

"We conclude that LCIB functions downstream of CAH3 in the CO2-concentrating mechanism and probably plays a role in trapping CO2 released by CAH3 dehydration of accumulated Ci."

"is proposed to play a role in trapping CO(2) released by CAH3 (thylakoid lumen carbonic anhydrase) catalyzed dehydration of accumulated Ci, especially in low CO(2) (L-CO(2); ~0.04% CO(2)) conditions."

"LCIB, which has been demonstrated as a key player in the eukaryotic algal CO2-concentrating mechanism (CCM), is a novel protein in Chlamydomonas lacking any recognizable domain or motif, and its exact function in the CCM has not been clearly defined."

"Although both LCIA and LCIB are essential for very low CO2 acclimation, LCIB appears to function in a CO2 uptake system, whereas LCIA appears to be associated with a HCO3(-) transport system."

"Collectively, the data presented here provide compelling evidence that HLA3 is directly or indirectly involved in HCO 3 − transport, along with additional evidence supporting a role for LCIA in chloroplast envelope HCO 3 − transport and a role for LCIB in chloroplast Ci accumulation."

"LC-inducible protein B (LCIB), structurally characterized as carbonic anhydrase, localizes in the chloroplast stroma under CO2-supplied and LC conditions."

"In VLC conditions, it migrates to aggregate around the pyrenoid, where the CO2-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase is enriched."

"These results suggest that the localization changes of LCIB require LCIC and are controlled by CO2 concentration with ∼7 µM as the boundary."

"In B3 cells, LCIC (49 kDa), the interacting protein of LCIB (48 kDa), was also hardly detected as with the previously reported LCIB RNAi strains"

"These results suggest that the starch sheath around the pyrenoid is required for the correct localization of LCIB and for the operation of CCM."

"Because LCIB and LCIC do not have a starch-binding domain and exist as soluble proteins in the chloroplast stroma"

"abl-1 and abl-3 with dispersed and speckled localization of LCIB in the chloroplast showed significant decreases in Ci affinity, Ci accumulation, and CO2 fixation."

"Consequently, LCIB relocalized near the starch sheath increases energy efficiency by recapturing CO2 molecules that diffuse out of the matrix and trapping them as HCO3− in the chloroplast"

"EPYC1, LCIB and LCIC (Figure 5F)."