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Publication Abstract from PubMed

Aquatic microalgae have evolved diverse CO2-concentrating mechanisms (CCMs) to saturate the carboxylase with its substrate, to compensate for the slow kinetics and competing oxygenation reaction of the key photosynthetic CO2-fixing enzyme rubisco. The limiting CO2-inducible B protein (LCIB) is known to be essential for CCM function in Chlamydomonas reinhardtii To assign a function to this previously uncharacterized protein family, we purified and characterized a phylogenetically diverse set of LCIB homologs. Three of the six homologs are functional carbonic anhydrases (CAs). 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 beta-CAs. Our results identify the LCIB family as a previously unidentified group of beta-CAs, and provide a biochemical foundation for their function in the microalgal CCMs.

Structural insights into the LCIB protein family reveals a new group of beta-carbonic anhydrases.,Jin S, Sun J, Wunder T, Tang D, Cousins AB, Sze SK, Mueller-Cajar O, Gao YG Proc Natl Acad Sci U S A. 2016 Dec 20;113(51):14716-14721. doi:, 10.1073/pnas.1616294113. Epub 2016 Dec 1. PMID:27911826^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.