3b1b

Publication Abstract from PubMed

Chlamydomonas reinhardtii alpha-type carbonic anhydrase (Cr-alphaCA1) is a dimeric enzyme that catalyses the interconversion of carbon dioxide and carbonic acid. The precursor form of Cr-alphaCA1 undergoes post-translational cleavage and N-glycosylation. Comparison of the genomic sequences of precursor Cr-alphaCA1 and other alphaCAs shows that Cr-alphaCA1 contains a different N-terminal sequence and two insertion sequences. A 35-residue peptide in one of the insertion sequences is deleted from the precursor during maturation. The crystal structure of the mature form of Cr-alphaCA1 has been determined at 1.88 A resolution. Each subunit is cleaved into the long and short peptides, but they are linked together by a disulfide bond. The two subunits are linked by a disulfide bond. N-Glycosylations occur at three asparagine residues and the attached N-glycans protrude into solvent regions. The subunits consist of a core beta-sheet structure composed of nine beta-strands. At the centre of the beta-sheet is the catalytic site, which contains a Zn atom bound to three histidine residues. The amino-acid residues around the Zn atom are highly conserved in other monomeric and dimeric alphaCAs. The short peptide runs near the active site and forms a hydrogen bond to the zinc-coordinated residue in the long chain, suggesting an important role for the short peptide in Cr-alphaCA1 activity.

The unique structure of carbonic anhydrase alphaCA1 from Chlamydomonas reinhardtii.,Suzuki K, Yang SY, Shimizu S, Morishita EC, Jiang J, Zhang F, Hoque MM, Sato Y, Tsunoda M, Sekiguchi T, Takenaka A Acta Crystallogr D Biol Crystallogr. 2011 Oct;67(Pt 10):894-901. Epub 2011 Sep 8. PMID:21931221^[1]

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