DurreShahwar (Durre) Muhammad

Research Area: Cell and Developmental Biology, Plant Environment Interactions

Field of Study: Plant peroxisome proteostasis and recycling

Peroxisomes are fascinating metabolic organelles and house numerous reactions required for life in plants. The metabolism and resulting byproducts that occur in peroxisomes are ripe for exploration. A hallmark metabolic reaction in peroxisomes is fatty acid β-oxidation; in plants, β-oxidation only occurs in peroxisomes. Plant peroxisomes also sequester the glyoxylate cycle, which allows pre-photosynthetic seedlings to catabolize stored lipids to synthesize carbohydrates and biosynthesis of phytohormones, including auxin, jasmonic acid, and salicylic acid, which regulate plant growth and development and responses to abiotic and biotic stress. These same peroxisomal reactions rely on metabolite exchange with other subcellular compartments and generate reactive oxygen species (ROS), including hydrogen peroxide and superoxide radicals, and reactive nitrogen species (RNS), such as nitric oxide. 

To maintain intralumenal proteostasis and protect against cellular damage, peroxisomes also contain antioxidant systems that decompose ROS and RNS. When these antioxidant systems are inadequate, protein damage ensues, requiring additional quality control mechanisms. For example, obsolete and damaged peroxisomes are degraded via pexophagy, a specialized form of autophagy.

Despite the importance of peroxisomes and their vital interactions with other essential organelles, knowledge of the mechanisms involved in peroxisome quality control, peroxisome turnover, and the cellular signaling that arises when peroxisomes are dysfunctional is minimal. The Muhammad lab seeks to understand how peroxisomes maintain proteostasis and, by extension, whole-cell homeostasis in a high oxidative stress environment using Arabidopsis thaliana.

Research:

(1) We aim to evaluate the role of proteases, chaperones, and oxidative detoxicants in peroxisomal and whole-cell homeostasis and the mechanisms governing the fine balance of protein repair and degradation in peroxisomes.

(2) We are assessing the effects on other subcellular compartments stemming from peroxisome dysfunction.

(3) We are utilizing Fe stress to elucidate the intricacies of peroxisome dynamics in abiotic stress response.

Our research uses a combination of genetic, molecular, cellular, biochemical, and systems approaches/techniques. We welcome inquiries from prospective undergraduate and graduate students, postdocs, and technicians.