Abstract
Chlorophyllide a oxygenase (CAO) synthesizes chlorophyll b from chlorophyll a and is encoded by nuclear genomes in higher plants. The enzyme regulates the formation of light harvesting complex (LHC) by controlling the synthesis of chlorophyll b. It is important to determine the localization of CAO in chroloplasts to understand the mechanism of LHC formation.
Comparison of various CAO amino acid sequences and computer prediction analysis showed that Arabidopsis CAO is composed of four domains, i.e., transit peptide (36 residues), A domain (134), B domain (30) and C domain (336). In this study, GFP (green fluorescence protein) fused with various CAO domain(s) were expressed transiently in pea leaves or stably in Arabidopsis transformants. The localization of CAO domain(s)-GFP was investigated by fluorescence microscopy. The results showed the different localization patterns of these proteins, suggested that the C domain has an important role in localization of CAO in chloroplasts.
