Presentation Title

Allostery as a Mechanism for Regulated Degradation: Evolving From Allostery to Mallostery

Faculty Mentor

Randy Hampton

Start Date

23-11-2019 10:45 AM

End Date

23-11-2019 11:30 AM

Location

92

Session

poster 4

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Our lab has discovered that the key sterol pathway enzyme HMGR is regulated by a novel mechanism employing a cellular quality control pathway normally involved in degradation of misfolded proteins. Feedback-regulated HMGR degradation occurs when a sterol pathway metabolite binds to HMGR, causing it to misfold, and thus undergo quality control destruction. HMGR regulated degradation has many similarities to allosteric regulation, and thus we call this ligand-mediated misfolding and degradation of HMGR “mallostery” to highlight those similarities. We hypothesize that mallosteric regulation can arise naturally by modification of an ancestor allosteric protein.

We are directly testing this idea with molecular genetics to generate and screen for mallosteric variants of the well-known allosteric protein chorismate mutase (CM). The desired mallosteric CM variants would undergo degradation when exposed to one of the known allosteric regulators that control normal CM activity. To this end we have created a screening platform that allows rapid creation of sequence variants of CM, combined with facile optical and functional assays to evaluate stability and ligand-stimulated degradation of the new CM variants. We have confirmed that this mutagenic and optical pipeline will effectively detect CM variants that undergo degradation, setting the stage for discovery of true mallosteric versions of CM. Ultimately, our studies will test the possibility that an evolutionary route exists in which allosteric regulation of enzyme function can be converted into ligand-mediated regulation enzyme levels. Furthermore, the feasibility of creating mallosteric variants of natural proteins would also imply that small molecule screens could be used to discover new mallosteric regulators of clinical targets as an untapped strategy of drug discovery.

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Nov 23rd, 10:45 AM Nov 23rd, 11:30 AM

Allostery as a Mechanism for Regulated Degradation: Evolving From Allostery to Mallostery

92

Our lab has discovered that the key sterol pathway enzyme HMGR is regulated by a novel mechanism employing a cellular quality control pathway normally involved in degradation of misfolded proteins. Feedback-regulated HMGR degradation occurs when a sterol pathway metabolite binds to HMGR, causing it to misfold, and thus undergo quality control destruction. HMGR regulated degradation has many similarities to allosteric regulation, and thus we call this ligand-mediated misfolding and degradation of HMGR “mallostery” to highlight those similarities. We hypothesize that mallosteric regulation can arise naturally by modification of an ancestor allosteric protein.

We are directly testing this idea with molecular genetics to generate and screen for mallosteric variants of the well-known allosteric protein chorismate mutase (CM). The desired mallosteric CM variants would undergo degradation when exposed to one of the known allosteric regulators that control normal CM activity. To this end we have created a screening platform that allows rapid creation of sequence variants of CM, combined with facile optical and functional assays to evaluate stability and ligand-stimulated degradation of the new CM variants. We have confirmed that this mutagenic and optical pipeline will effectively detect CM variants that undergo degradation, setting the stage for discovery of true mallosteric versions of CM. Ultimately, our studies will test the possibility that an evolutionary route exists in which allosteric regulation of enzyme function can be converted into ligand-mediated regulation enzyme levels. Furthermore, the feasibility of creating mallosteric variants of natural proteins would also imply that small molecule screens could be used to discover new mallosteric regulators of clinical targets as an untapped strategy of drug discovery.