Mechanistic Exploration of SmiA-Mediated Degradation of SwrA in Bacillus subtilis

Micah Greenzweig, Richard Knappenberger, and Dr. Vijay Parashar, Department of Medical and Molecular Sciences, University of Delaware, Newark, DE 19716

Cellular behavior is heavily dependent on protein degradation. In eukaryotes, it is understood that the major pathway for protein degradation involves substrate polyubiquitination followed by protease recognition and proteolysis of ubiquitin-marked targets. However, the prokaryotic equivalent of marking proteins for degradation is not equally understood. In prokaryotes, arginine phosphorylation of target proteins has been established as a signal for their degradation. In Bacilli, the known contributor for this phosphorylation is an arginine kinase, McsB, which coordinates bacterial stress response by phosphorylating arginines in misfolded proteins. Upon arginine phosphorylation, the misfolded proteins can be recognized and degraded by specific proteases. Despite knowledge of this mechanism, it is unknown whether McsB or other unidentified proteins regulate the degradation of non-misfolded proteins by similar post-translational modifications. Alternatively to the use of post-translational modifications as degradation markers, there is adaptor-mediated degradation, whereupon a secondary protein, called an adaptor, interacts with a target protein to act as the signal for its degradation. Recently, this mode of degradation was proposed to control swarming motility in Bacilli. Swarming motility is an emergent behavior that allows a bacterial colony to spread on solid surfaces. It has been proposed that to regulate this behavior, Bacilli rely on adaptor-mediated proteolysis of SwrA, the protein that activates flagellar biosynthesis. In this proposed mechanism the adaptor protein, SmiA, interacts with SwrA and marks it for degradation by a protease. However, how SmiA acts as an adaptor to recognize SwrA remains unclear. Thus, we propose to elucidate the mechanism by which SmiA marks SwrA for degradation with the intention to analyze potential alternative proteolytic mechanisms in prokaryotes.

Additional Abstract Information

Presenter: Micah Greenzweig

Institution: University of Delaware

Type: Poster

Subject: Microbiology

Status: Approved

Time and Location

Session: Poster 8
Date/Time: Tue 5:00pm-6:00pm
Session Number: 5639