PARENT SESSION
Posters P3D Genomic, proteomic and related technologies. Abstracts (720-730)

A proteomic study of carboxysomes from -cyanobacteria. Ben Long^*,1, G Price¹, Murray Badger¹, ¹ Molecular Plant Physiology Group, Canberra, ACT, Australia

ABSTRACT- Carboxysomes are protein-bound, polyhedral structures within cyanobacteria, containing the key enzyme for photosynthetic CO₂-fixation, namely Rubisco. Sequencing of cyanobacterial genomes has revealed that cyanobacteria possess one, or other, of two types of carboxysomes. Cyanobacteria containing Form-1A Rubisco (e.g. Prochlorococcus marinus MED4) possess -carboxysomes, while those with Form-1B Rubisco possess -carboxysomes (e.g. Synechococcus PCC7942). Given the central importance of carboxysomes in the CO₂ concentrating mechanism (CCM) of cyanobacteria, understanding the nature and composition of these structures is of considerable importance. In an effort to characterise the structure of -carboxysomes, particularly the outer protein shell, we have undertaken a proteomic analysis of these structures from the freshwater cyanobacterium Synechococcus sp. PCC7942. Both MALDI-TOF analysis of excised SDS-PAGE bands and MuDPIT analysis of complex mixtures of digested proteins have been used in an attempt to identify the proteins constituting -carboxysomes. We report here some preliminary data on the identity of proteins associated with -carboxysomes from Synechococcus sp. PCC7942.

KEY WORDS: carboxysomes, CO₂ concentrating mechanism, cyanobacteria, proteomics