Chloroplast biogenesis is the fundamental to the productivity mechanism by plants, of which, protein targeting to chloroplast is a prerequisite. Toc159 and the other members of the Toc159 family (e.g. Toc132) serve as the primary receptors. The working model hypothesizes that Toc159 and Toc132 are functionally distinguishable in that they preferentially recognize photosynthetic and non-photosynthetic chloroplast preproteins, respectively. Nevertheless, relatively few chloroplast preproteins have been confirmed as substrates for particular members of the Toc159 family, which limits the proof for the preprotein specificity hypothesis. My current research focuses to expand the number of known preprotein substrates for the Toc159 family of receptor(s) through library screening based on Split-ubiquitin membrane-based yeast two-hybrid system. Initially by using Toc159 G-domain as the bait, and expanding it to include Toc132 and other domains of Toc159 family (i.e. the A-domain), I hope to shed more light on how preprotein substrate selectivity of Toc159/Toc132 is achieved.

Dr Siddhartha Dutta
Postdoctoral Fellow, Biology