Leonard Beevers

The majority of the volume of the mature plant cell is occupied by the vacuole. The vacuole is the site of accumulation of ions, sugars, amino acids, secondary metabolites and hydrolytic enzymes, thus the vacuole serves both a storage and lytic function. Because of the presence of acid hydrolases in plant vacuoles they have been likened to the lysosome of mammalian cells.

For the past several years in our laboratory, we have been investigating the intracellular transport of proteins to the plant vacuole. The hydrolytic enzymes of the plant vacuole are synthesized as precursors on the endoplasmic reticultum (ER). Subsequently, the precursor protein are transported to the Golgi apparatus where they may undergo processing and packaging. This pathway, ER to Golgi, is the identical route followed by proteins destined for the plasma membrane and the cell wall.

We have demonstrated that clathrin coated vesicles contain vacuolar acid hydrolases and have proposed that these organelles are involved in the selective recruitment of materials from the Golgi apparatus for ultimate deposition into the vacuole. In support of this contention, we have identified a 80kDa protein in the clathrin coated vesicle membranes which interacts specifically with peptides which have been identified as vacuolar targeting determinants. Thus, the 80kDa protein functions as a selective receptor for proteins destined to the vacuole.

We are currently investigating the mechanisms by which the 80kDa receptor/ligand complex is retrieved and incorporated into the clathrin coated vesicles. For this purpose we have successfully isolated clathrin coated vesicles in high yields from developing pea cotyledons and wheat germ. The vesicles are being used as a source of clathrin components (heavy and light chains) and adaptors or assembly proteins. The roles of the individual components in vesicle assembly are being assessed by immunolgoical and molecular procedures and affinty chromatography to identify peptide-protein interactions.

Selected Publications

• Cao, X., Rogers, S.W., Butler, J., Beevers, L., Rogers, J.C. 2000. Structural requirements for ligand binding by a probable plant vacuolar sorting receptor. Plant Cell 12, 493-506
• Beevers, L., Raikhel, N.V. 1998. Transport to the vacuole: Receptors and trans elements. Journ. of Exp. Bot. 49: 1271-1279.
• Paris, N., Rogers, S.W., Jiang, L., Kirsch, T., Beevers, L., Phillips, T.C., Rogers, J.C. 1997. Molecular cloning and further characterization of a probable plant vacuolar sorting receptor. Plant Physiol. 119: 29-39.
• Beevers, L. 1996. Clathrin-Coated Vesicles in Plants. Int. Rev. Cytol. 167 1-35.
• Kirsch, T., G. Saalbach, N.V. Raikhel and L. Beevers. 1996. Interaction of a potential vacuolar targeting receptor with Amino-and Carboxyl-Terminal targeting determinants. Plant Physiol. III 469-474.
• Kirsch, T., N. Paris, J.M. Butler, L. Beevers and J.C. Rogers. 1994. Purification and initial characterization of a potential plant vacuolar targeting receptor. Proc. Natl. Acad. Sci, USA 91 3403-3407.

For more information about this program, email the Department or Dr. Leonard Beevers.

Other related web pages:

• Department of Botany & Microbiology