This research will determine the function of subtilase genes in Arabidopsis. Subtilase genes encode subtilisin-like serine proteases, proteins that play important roles in plant growth and development. In mammalian systems, some subtilases are called "hormone convertases" because they cut other proteins releasing bioactive peptides that serve as hormones and/or function in cell-to-cell signaling. The properties of some plant subtilases suggest they may play similar roles in plant development and physiology.
The function of nearly 60 subtilase genes in Arabidopsis will be investigated through collaboration with European partners in The Arabidopsis Subtilase Consortium (TASC). A listing of all the genes in the subtilase gene family (and their subfamily identification) is found at http://csbdb.mpimp-golm.mpg.de/csbdb/dbcawp/psdb/main/mgenes.html. This research will focus on the role of ten subtilase genes that are highly regulated during shoot regeneration in tissue culture. Three of these subtilase genes appear to influence shoot development in that the expression of these genes is controlled by a major quantitative trait locus (QTL) that determines shoot regeneration efficiency. Shoot regeneration efficiency varies in Arabidopsis and in some important economic crops where it can impede the successful application of genetic engineering technologies. Another seven subtilase genes are differentially regulated during shoot or root regeneration.
A proteomics approach (the study of a large number of proteins using protein expression profiling) will be used to understand the function of the subtilases. The function of these genes in vivo will be examined by quantitatively analyzing 2D difference gel electrophoresis (DIGE) profiles of T-DNA insertion mutants and transgenics with induced expression of subtilase genes. Subtilase target sites will be determined by analyzing the products from the limited digestion of common substrate proteins by the recombinant enzyme. Optimal subtilase target sites will be determined by designing and testing the hydrolysis of synthetic peptides related to the cleavage sites for common substrates.
Research results will shared with the public and other members of the scientific community through http://csbdb.mpimp-golm.mpg.de/csbdb/dbcawp/psdb.html. Information at this site is edited by the Altmann lab and will be updated on a monthly basis. This research is significant to the goals of the 2010 project in that it contributes to our understanding of a group of important genes that influence plant growth and development. This research makes a unique contribution in that it uses new tools in proteomics to address gene function.
Broader impact
This project has broader impact because it contributes knowledge to the role of proteolysis and peptide signaling in plant development. Little is known about bioactive plant peptides from genomics because peptides are often embedded in other proteins and are not released until cleaved by proteases, such as subtilases.
The project also has broader impact because it provides lab research training for Iowa State University and Des Moines Area Community College undergraduates. Some of the undergraduate trainees will also have the opportunity to conduct research during the summer in international labs of partners associated with TASC. To encourage ISU minority undergrads to participate in this project, we will host a meeting each fall in the Roy J. Carver Co-Laboratory for the local chapter of Minorities in Agriculture, Natural Resources and Related Sciences (MANRRS).
