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K-State Today

October 17, 2023

Jeroen Roelofs to present Biochemistry and Molecular Biophysics Seminar

Submitted by Biochemistry and Molecular Biophysics

Jeroen Roelofs, professor of biochemistry and molecular biology at the University of Kansas Medical Center, will be the featured speaker for this week's Biochemistry and Molecular Biophysics Seminar. Roelofs will present "Stress induced relocalization of proteasomes into condensates" at 4 p.m. Wednesday, Oct. 18, in 120 Ackert Hall.

To cope with changes in physiological conditions, cells adjust the levels and localization of many proteins. Proteasomes contribute to this process through their ability to degrade proteins and thus are a critical component of the proteostasis network that maintains protein homeostasis. Interestingly, some stress conditions also trigger the localization of proteasomes from the cytoplasm or nucleoplasm into molecular condensates both in yeast and mammalian cells. The interactions that facilitate the formation of proteasome condensates, however, have been poorly defined. Roelofs will discuss recent work in yeast that supports a model where the cellular accumulation of substrates with long ubiquitin chains, potentially due to reduced cellular energy, allows for proteasome condensate formation. The long poly-ubiquitin chains function as scaffolds where multivalent interactions with the ubiquitin binding domains of proteasome shuttle factors and proteasomes themselves drive condensate formation. In all, our research suggests that proteasome condensates are not simply for proteasome storage but function to sequester soluble ubiquitinated substrates together with proteasomes.