Engineered resistance against proteinases

Exogenous proteinase inhibitors are valuable and economically interesting protective biotechnological tools. We examined whether small proteinase inhibitors when fused to a selected target protein can protect the target from proteolytic degradation without simultaneously affecting the function and activity of the target domain. Two proteinase inhibitors were studied: a Kazal-type silk proteinase inhibitor (SPI2) from Galleria mellonella, and the Cucurbita maxima trypsin inhibitor I (CMTI I). Both inhibitors target serine proteinases, are small proteins with a compact structure stabilized by a network of disulfide bridges, and are expressed as free polypeptides in their natural surroundings. Four constructs were prepared: the gene for either of the inhibitors was ligated to the 5' end of the DNA encoding one or the other of two selected target proteins, the coat protein (CP) of Potato potyvirus Y or the Escherichia coli β-glucuronidase (GUS). CMTI I fused to the target proteins strongly hampered their functions. Moreover, the inhibitory activity of CMTI I was retained only when it was fused to the CP. In contrast, when fused to SPI2, specific features and functions of both target proteins were retained and the inhibitory activity of SPI2 was fully preserved. Measuring proteolysis in the presence or absence of either inhibitor, we demonstrated that proteinase inhibitors can protect target proteins used either free or as a fusion domain. Interestingly, their inhibitory efficiency was superior to that of a commercial inhibitor of serine proteinases, AEBSF

Genomic data from the potato

Available here is the genome of the potato (Solanum tuberosum L.), the first genome sequenced from the asterid clade. Potato is a member of the Solanaceae, a plant family that includes many other economically important species, such as tomato, petunia, eggplant, tobacco, and pepper. As the potato is both clonally propagated and the world;s most important non-grain food crop, its genome is a valuable agricultural resource. The Potato Genome Sequencing Consortium sequenced two species: the heterozygous diploid S. tuberosum Group Tuberosum cultivar, RH89-039-16 (RH), and the doubled monoploid S. tuberosum Group Phureja clone DM1-3 516R44 (DM). The potato genome consists of 12 chromosomes, of which over 80% of the homozygous clone’s 844-megabase genome were assembled. Genome analysis revealed evidence of at least two genome duplication events and identified a number of asterid-specific genes. Comparison between the two clones identified frequent gene variations and mutations, which may cause inbreeding depression