The general aim of the group is to develop adequate tools for a better knowledge of plant morphogenesis and differentiation, as well as applied aspects related to plant improvement. Currently, studies related to the enzyme transglutaminase (TGase) are the main goal of the group. This enzyme catalyzes post-translational modifications of proteins through covalent linkage of substrates with primary amino groups, such as polyamines, to a gamma-carboxiamide group of protein endo-glutamine residues. TGases are widely distributed and play a fundamental role in cellular differentiation, tissue stabilization and apoptosis.
We have accomplished, for the first time in plants, the cloning of two cDNAs that codify for maize chloroplast TGase (tgz), which we are characterising using molecular, cellular and proteomic approaches. We have already demonstrated that enzyme activity is stimulated by light and preferably located in the grana of the differentiated chloroplasts, where photosystem II is prevalent. We propose an involvement of polyamine by means of TGase activity in photo-protection of the phothosynthetic apparatus. Also, available evidence indicates that grana remodelling may be possible through over-expression of a single enzyme, and suggesting that tgz has an important functional role in grana stacking.