Structural basis of the oxidative activation of the carboxysomal gamma-carbonic anhydrase, CcmM.

ABSTRACT: Cyanobacterial RuBisCO is sequestered in large, icosahedral, protein-bounded microcompartments called carboxysomes. Bicarbonate is pumped into the cytosol, diffuses into the carboxysome through small pores in its shell, and is then converted to CO(2) by carbonic anhydrase (CA) prior to fixation. Paradoxically, many beta-cyanobacteria, including Thermosynechococcus elongatus BP-1, lack the conventional carboxysomal beta-CA, ccaA. The N-terminal domain of the carboxysomal protein CcmM is homologous to gamma-CA from Methanosarcina thermophila (Cam) but recombinant CcmM derived from ccaA-containing cyanobacteria show no CA activity. We demonstrate here that either full length CcmM from T. elongatus, or a construct truncated after 209 residues (CcmM209), is active as a CA-the first catalyticall

SUBMITTER: Pena KL 

PROVIDER: S-EPMC2823891 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature