Department Seminar

Upcoming Seminar

The role of a disulfide in protein folding and stability
Prof. Karin Crowhurst, CSU Northridge

October 7, 2026
4:00pm-5:00pm in HSCI-103

Abstract

HdeA is one of the smallest known chaperones. It is located in the periplasm of several common pathogenic bacteria and is a major contributor to the infectivity of these organisms in causing dysentery. HdeA is considered a conditionally disordered protein, in that it is activated at low pH by unfolding and binding to other unfolded periplasmic proteins to prevent their irreversible aggregation. It also facilitates refolding once the bacteria transition to a higher pH when they travel into the intestinal region to infect the host. HdeA is a small homodimer; one of its key features is a single disulfide that helps the protein to maintain some partial structure to carry out its chaperone activities at low pH.

Our lab has been interested in further studying this disulfide bond to determine how critical its presence and positioning is to the refolding, stability and function of HdeA, both from the perspective of its activities as an acid-stress chaperone and to gain insight into the role of disulfides as a whole. Because of the need to evaluate the effects of these mutations with high precision, our primary tools of investigation are atomic resolution NMR and molecular dynamics simulations. Our experiments revealed some unexpected results regarding protein folding pathways, the ability of HdeA to be a chaperone in the absence of the disulfide, and the stability of the protein when the disulfide was removed altogether.

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