Alkaloids;Catharanthus roseus;MALDI-MS/MS;terpenoid indole alkaloids;MudPIT;terpenes
Madagascar periwinkle (Catharanthus roseus) is the major source of terpenoid indole alkaloids, such as vinblastine or vincristine, used as natural drugs against various cancers. In this study, we have extensively analyzed the proteome of cultured C. roseus cells. Comparison of the proteomes of two independent cell lines with different terpenoid indole alkaloid metabolism by 2D-DiGE revealed 358 proteins that differed quantitatively by at least a two-fold average ratio. Of these, 172 were identified by mass spectrometry; most corresponded to house-keeping proteins. Less abundant proteins were identified by LC separation of tryptic peptides of proteins from one of the lines. We identified 1,663 proteins, most of which are housekeeping proteins or involved in primary metabolism. However, 63 enzymes potentially involved in secondary metabolism were also identified, of which 22 are involved in terpenoid indole alkaloid biosynthesis and sixteen are predicted transporters putatively involved in secondary metabolite transport. About 30% of the proteins identified have an unclear or unknown function, indicating important gaps in knowledge of plant metabolism. This study is an important step towards elucidating the proteome of C. roseus, which is critical for a better understanding of how this plant synthesizes terpenoid indole alkaloids.