Extracellular Matrix Metalloproteinases
and Plant Development

The plant extracellular matrix (ECM) consists of a complex mix of proteins that serve critical roles in the regulation of plant growth and development. Several studies have shown that various ECM proteins are subjected to proteolytic modification during plant development cycle. Extracellular matrix metalloproteinases (MMPs) are known modifiers of the mammalian ECM, and are implicated in changes of tissue architecture and the release of biologically active and/or signaling molecules.  Although MMPs have also been found in plants, little is known about their activity and function. The plant MMPs show structural similarity to mammalian MMPs, including the presence of an autoregulatory cysteine-switch domain, a zinc-binding catalytic domain, and in some cases, predicted furin cleavage sites and glycosylphosphatidylinositol (GPI) anchor sites and/or C-terminal transmembrane anchor domains. Plant MMPs are differentially expressed in cells and tissues during plant growth and development, as well as in response to several biotic and abiotic stresses. Gene expression and minimal mutant analyses to date suggest their involvement in plant growth, morphogenesis, senescence and adaptation, or response, to stress. In order to gain a further understanding, an analysis and characterization of MMP proteins and their activity during plant growth and development are still required. Additionally, the identification of MMP proteolytic substrates would help elaborate their roles in plant development, and generate knowledge regarding the role of extracellular proteases in the control of plant developmental signaling. A variety of genomic and proteomic methodologies exist to characterize plant MMP activity and the putative MMP substrates.

Our research program concentrates primarily on the role of MMPs in embryo/seed development, but also overall plant development.  Loblolly pine and Korean fir are primary experimental systems, as well as potato and the model plant, Arabidopsis thaliana.   In addition to in planta analyses, recombinant MMPs have been generated and are being used for biochemical characterization of these proteases.