PARENT SESSION
Posters P3C C3 and Rubisco. Abstracts (617-630)

An in vivo analysis of the function of rbcX by insertional disruption in Synechococcus PCC7942. Daniel Emlyn-Jones^*,1, John Andrews¹, ¹ Molecular Plant Physiology, Research School of Biological Sciences, Australian National University, Canberra, A.C.T., Australia

ABSTRACT- The gene rbcX, found in all the beta-cyanobacteria is almost always situated between the Rubisco large and small subunit genes rbcL and rbcS. rbcX from different cyanobacteria share moderate homology but have no other significant homologs that might indicate a particular function. It has been suggested that the position of rbcX between rbcL and rbcS is not fortuitous and that RbcX is a chaperonin for Rubisco, a hypothesis for which there is some evidence. In the complete genome sequence of Synechococcus PCC7942 there are no ORFs between rbcL and rbcS, but there is an rbcX situated over 100kb away from the rubisco genes. The unique remote positioning of rbcX in this organism provides an excellent system for in vivo analysis of rbcX function by insertional inactivation since the rbcLS locus can be left undisrupted. rbcX has been insertionally inactivated in Synechococcus PCC7942 replacing an internal segment of the rbcX gene with a Kanamycin resistance marker. The inactivation segregated rapidly to complete homoplasmicity in these mutants indicating that the gene is not essential. Western analysis of Rubisco content in transformants showed there to be no gross changes compared with the Wild Type. More detailed characterisation of these mutants will be presented.

KEY WORDS: rubisco, chaperone, cyanobacteria, photosynthesis