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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/24531

Title: Identification of a Carboxysomal γ-Carbonic Anhydrase in the Mesophilic Cyanobacterium Anabaena sp. PCC7120
Authors: Arefeen, Dewan
Advisor: Espie, George
Department: Cell and Systems Biology
Keywords: Cyanobacteria
Carbonic anhydrase
Anabaena PCC7120
CcmM
Carboxysome
Carbon dioxide concentrating mechanism
Issue Date: 21-Jul-2010
Abstract: Analysis of the genome of Anabaena sp. PCC7120 reveals that it lacks the gene, ccaA, which encodes the bonafide carboxysomal, β-class carbonic anhydrase (CA) CcaA. However, the carboxysome enriched fraction of Anabaena PCC7120 exhibits CA activity. Bioinformatic analysis reveals that the N-terminal region of the carboxysome protein CcmM has high sequence and structural similarity to the γ-class CA of Methanosarcina thermophila. Recombinantly expressed CcmM is found to be inactive in in-vitro CA assays. E. coli cell extracts containing an overexpressed form of CcmM comprised of the N-terminal 209 amino acids (CcmM209) are also inactive. However, CcmM209 displays CA activity after incubation with the thiol oxidizing agent diamide or when bound to an affinity matrix. It appears that CcmM is indeed a functional γ-CA which is active under oxidizing condition. It is hypothesized that the C-terminal RbcS like domain in CcmM may regulate activity by allowing CcmM activation only when sequestered within the carboxysome.
URI: http://hdl.handle.net/1807/24531
Appears in Collections:Master
Department of Cell and Systems Biology - Master theses

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