PMID:20660228

Light and low-CO2-dependent LCIB-LCIC complex localization in the chloroplast supports the carbon-concentrating mechanism in Chlamydomonas reinhardtii.

LCIC interacts with LCIB in yeast two-hybrid and in vivo

"LCIB interacts with the LCIB homologous protein LCIC in yeast and in vivo"
LCIB and LCIC co-localize near the pyrenoid under low CO2 in the light as a ~350 kDa hexameric complex

"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"

PMID:27911826

Structural insights into the LCIB protein family reveals a new group of β-carbonic anhydrases.

Crystal structure of Chlamydomonas LCIC shows a beta-CA-like active-site motif

"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"
Only some LCIB-family homologs are active carbonic anhydrases

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

PMID:28938113

A Spatial Interactome Reveals the Protein Organization of the Algal CO(2)-Concentrating Mechanism.

LCIC-mCherry co-localizes with LCIB in puncta at the pyrenoid periphery

"LCIB and LCIC were co-localized (Figure 4D)"
LCIB and LCIC form punctate outer layer around the pyrenoid

"1) LCIB and LCIC localize to puncta around the periphery"
LCIC puncta lie outside the starch sheath (STA2 plates lie inside the LCIC perimeter)

"STA2 was localized within the perimeter described by LCIC"
LCIB and LCIC are stromal soluble proteins in a tight complex

"Our data confirm that LCIB and LCIC, known stromal soluble proteins, are in a tight complex"
Recombinant LCIB/C lacked carbonic anhydrase activity

"However, recombinant LCIB/C had no carbonic anhydrase function"
LCIC interacts with bestrophin-like proteins LCI11 and Cre16.g662600

"Both LCIB and LCIC interact with LCI11 (Cre16.g663450), and LCIC also interacts with Cre16.g662600"
Two competing models of LCIB/C function

"This complex is hypothesized to either form a CO2 leakage barrier at the pyrenoid periphery or to act as a vectorial CO2 to HCO3− conversion module to recapture CO2 that escapes from the pyrenoid"

PMID:34791500

CO2-dependent migration and relocation of LCIB, a pyrenoid-peripheral protein in Chlamydomonas reinhardtii.

LCIC is required for LCIB to migrate to the pyrenoid periphery

"LCIB migration to around the pyrenoid required the accumulation of LCIC in the Chlamydomonas chloroplast"
LCIC protein is absent in the lcib mutant

"This is consistent with the results that the accumulation of LCIC was also missing in the lcib mutant"
Recombinant and native LCIB/LCIC proteins lack CA activity

"Recombinant LCIB, LCIC, LCIB-LCIC complex, and native LCIB-LCIC complex do not have CA activity (Jin et al., 2016)"
The LCIB and LCIC structures have a zinc-coordinating beta-CA active site

"the crystalline structures of these proteins resemble that of β-type carbonic anhydrase (CA), which possesses an active CA site that coordinates with a zinc ion"
Possible regulation of CA activity by LCIB/LCIC association

"it cannot yet be ruled out the possibility that the putative CA activity is regulated by the complex formation and dissociation of LCIB and LCIC in response to CO2 concentration"

PMID:36856938

LCIB functions as a carbonic anhydrase: evidence from yeast and Arabidopsis carbonic anhydrase knockout mutants.

CA activity of LCIB/LCIC had not been demonstrated before 2023

"Although both LCIB and LCIC are structurally similar to βCAs, their CA activity has not been demonstrated to date"
LCIB (not LCIC) complements CA-deficient yeast and Arabidopsis

"We provide evidence that LCIB is an active CA using a Saccharomyces cerevisiae CA knockout mutant"

PMID:24307449

LCIB in the Chlamydomonas CO2-concentrating mechanism.

The precise function of LCIB in the CCM is undefined

"its exact function in the CCM has not been clearly defined"

PMID:15235119

Expression profiling-based identification of CO2-responsive genes regulated by CCM1 controlling a carbon-concentrating mechanism in Chlamydomonas reinhardtii.

Genome-wide screen identifying CCM1-dependent low-CO2 inducible genes (the source of the LciC cDNA, AB168094)

"51 low-CO2 inducible genes"