Abstract
Non specific lipid transfer proteins (nsLTPs) form a multigenic protein family in plants. These proteins are characterized by their capacity to in vitro bind different lipids, such as fatty acids and phospholipids. Their functions in vivo are still unclear, even if it has been hypothesized a role for LTP in the assembly of extra cellular hydrophobic polymers (e.g. cutin and suberin), in signalling and in plant defence against pathogens. A root specific nsLTP mRNA (MtN5) has been identified in Medicago truncatula and it has been reported to be expressed during the early phases of nodulation. It has been proposed that MtN5 could be involved either in a general defence mechanism against rhizobia or in Nod factor signalling. In this work we have studied the expression of MtN5 during the nodulation process induced by Sinorhizobium meliloti 1021 wild-type and by an engineered S. meliloti with enhanced capacity to nodulate M. truncatula. Furthermore, MtN5 (Y15371) cDNA has been cloned and expressed in a prokaryotic system (E. coli BL21 DE3 pLysS) in order to study its properties in vitro.