PARENT SESSION
Posters P7C Biosynthesis and assembly: Protein trafficking. Abstracts (681-684)

Purification and characterisation of Clp proteins from the cyanobacterium Synechococcus. Fredrik Andersson^*,1, Robert Blakytny¹, Jenny Schelin¹, Adrian Clarke¹, ¹ Botanical Institute, Gothenburg, Sweden

ABSTRACT- The ATP-dependent Clp protease found in eubacteria, plants and mammals consist of two functionally distinct subunits: a proteolytic core usually comprised of the ClpP protein, and a molecular chaperone that regulates substrate specificity and processing. The cyanobacterium Synechococcus elongatus has a multigene family encoding different isozymes of the proteolytic subunit ClpP. Multiple isomers of ClpP is common to both cyanobacteria and plant chloroplasts, as is the existence of a unique variant of ClpP known as ClpR. In contrast to ClpP, ClpR apparently lacks the conserved amino acids that constitute the catalytic active site characteristic of serine-type proteases like ClpP. The precise function of ClpR is as yet unknown, as is the structure and function of all Clp proteins in cyanobacteria. In order to gain more information regarding this family, various Clp proteins from Synechococcus are being purified using an E. coli-based over-expression system. Already purified has been the ClpP1 isomer, as well as the molecular chaperone ClpC. Cyanobacterial ClpP1 and ClpC show the characteristic peptidase and ATPase activities, respectively, of ClpP and Hsp100 chaperones in other organisms such as E. coli. Recently, the Synechococcus ClpP3 and ClpR proteins have also been purified using the same over-expression system. Using all the recombinant proteins purified so far, we are currently performing various in vitro biochemical assays to ascertain the functional activity of each protein and how they interact structurally.

KEY WORDS: molecular chaperone, protease, cyanobacteria, protein purification