ISOLATION AND CHARACTERISATION OF THE GENES ENCODING A THYLAKOID FK506-BINDING PROTEIN IN WHEAT

摘要

The FK506-binding proteins (FKBPs) are peptidyl prolyl cisltrans isomerase (PPIase) enzymes that catalyse the rotation of the proline peptide bond, which is a rate-limiting step in protein folding. In addition to their PPIase capabilities, several FKBPs are known to operate as molecular chaperones that interact with specific protein partners. Such interactions have been implicated in various cellular processes such as protein folding and trafficking, signal transduction and stress response (Galat, 2003). FKBPs are ubiquitous to all organisms studied and they often comprise large protein families. The higher plant genome encodes over twenty FKBPs, of which ten are predicted to be residents of the chloroplast thylakoid. Despite the relatively large lumenal FKBP population, characterisation of the cereal FKBPs has so far been limited to non-lumenal members, of which several are involved in heat stress response (Kurek et al 1999; Nigam et al 2008). Several lumenal FKBPs have been linked to assembly andstability of the photosynthetic apparatus (Gupta et al 2002; Lima et al 2006; P. Romano, unpublished) and it has been speculated that each may have a specific photosynthetic protein partner. Alternatively, the occurrence of multiple FKBPs in the thylakoid may indicate that some are induced in response to specific stress or development conditions.