Plant Productivity: How Chloroplasts Degrade and Recycle

Plant cells and organelles need a way to remove and recycle unwanted or damaged proteins, a kind of cleaning crew. Proteases do the job. Proteases are enzymes that break down proteins or peptides to amino acids in a process called proteolysis. In chloroplasts—essential organelles for plant productivity—removal and recycling of unwanted proteins involves a network of protease activities, but the determinants of chloroplast protein lifetime and degradation are poorly understood.

Klaas van Wijk, School of Integrative Plant Science, is working to uncover the network of chloroplast proteases and how those proteases interact with substrates and each other. His lab is studying a particularly complex protease system, Clp, to determine how it recognizes and degrades proteins involved in major chloroplast metabolic pathways, as well as to identify additional substrates with which it comes into contact. Other proteases (PREP and OPP) are also under investigation, including how they coordinate with and complement Clp.

While shedding light on the network of chloroplast proteases, the approach may also serve as an example for protease network discovery in other subcellular compartments. Research findings can be implemented in molecular farming and synthetic biology, since cellular compartments such as chloroplasts are favored for overexpression of products with nutritional or pharmaceutical value. Understanding how chloroplasts proteins accumulate will directly impact these applications.

The project will provide training at the undergraduate, graduate, and postdoctoral levels. It will offer summer internships through Cornell’s Research Experiences for Undergraduates program, sponsored by the National Science Foundation, and for high school students through the Cornell 4H extension program. In year two, the researchers will organize a plant proteolysis workshop to help train the next generation of scientists.

Cornell Researchers

Funding Received

$830 Thousand spanning 3 years