NSF-BSF: The impact of the KFERQ motif on protein turn-over in C. elegans

This collaborative project between U.S. and Israeli researchers will investigate how proteins are broken down into the basic units for recycling. The project focuses on an ancient form of degradation, where proteins are selected for breakdown on the basis of a specific motif in their protein sequence. Small roundworms were genetically engineered to carry this specific degradation motif fused to a fluorescent protein.

These engineered worms will be used to detect the fluorescent signal in living worms under microscopes and identify conditions that alter the intensity of the fluorescent signal. These conditions will identify the factors involved in protein degradation. Knowledge of the motif-sequence-mediated degradation pathway in worms will enable comparative analysis with vertebrates and other creatures and has the potential to discover the evolutionary origin of this mechanism, and identify conserved fundamental principles that will be relevant for mammalian biology as well.

Concurrently, the two researchers aim to increase participation in STEM. Graduate and undergraduate students will be trained in methods of scientific inquiry and communication skills. Students will be co-mentored in the expertise of both labs and will be exposed to joint group meetings and seminars in an international scientific environment.

Results of outreach will be assessed by the successful recruitment of these students, at different training levels at both institutions. This project has the combined goals of revealing a complex cellular process and increasing the network of STEM researchers.

Autophagy is an evolutionarily conserved process that mediates turnover of cytoplasmic material by the lysosome. There is a critical need to define the molecular mechanisms involved in degradation pathways, how they affect the proteome, and how they evolved. In mammals, the properties of the residues that constitute the KFERQ protein sequence motif determine whether the targeting chaperone HSC70 can bind and function in chaperone-mediated autophagy, or microautophagy.

Strikingly, although more than a third of the proteins in C. elegans carry a KFERQ-like motif, the molecular underpinnings of any alternative forms of autophagy besides macroautophagy have not been explored. The PIs have developed a KFERQ-sensor in C. elegans, which will be used to elucidate and dissect the genetic and molecular mechanisms that regulate protein turn-over via the KFERQ-like motif and determine its physiological relevance in C. elegans.

Identification of the KFERQ-mediated degradation pathway will enable a comparative analysis with higher organisms and has the potential to highlight the origin of this mechanism, enable the study of its evolution, and identify conserved fundamental principles that may be relevant for mammalian biology as well. This project will establish the relevance of the KFERQ-like penta-amino-acid motif to affect protein stability and degradation in C. elegans and use it to elucidate the likely ancestral pathway of degradation.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.