Semester

Spring

Date of Graduation

2024

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Biology

Committee Chair

Ashok Bidwai

Committee Member

Eric Horstick

Committee Member

Rita Rio

Abstract

The studies described here focus on mutations in protein kinase CK2 linked to ‘Okur-Chung’s Neuropathy’ (OCN), a neurodevelopmental disorder that involves 10 distinct mutations in the catalytic subunit CK2α. It has, however, remained unresolved if these mutations impair CK2α activity or if they also impair association with the regulatory CK2β subunit, which is necessary for assembly of the α2β2 holoenzyme. I describe efforts to resolve these questions for two mutations, Y50S and D175G. The former is thought to reside at the CK2α-CK2β interface, whereas the latter is located proximal to the active site. I therefore hypothesized that Y50S should perturb the CK2α-CK2β interactions without affecting enzyme activity, whereas D175G should abrogate activity but not the CK2α-CK2β interactions. I have used sequence conservation across diverse eukaryotic taxa, structural modeling of these two residues, functional complementation of yeast inviability, and yeast two hybrid assays to analyze CK2α harboring these two mutations in isolation. Paradoxically, these studies reveal that despite being invariant over 500 MYR (from yeast to human CK2), neither mutation appears to affect in vivo activity of CK2α or its interaction with CK2β. These findings raise questions on studies based on the crystal structure of CK2 that propose the importance of D175 in coordinating Mg2+- ATP, and the importance of Y50 to the CK2α-CK2β interface. The possibility thus arises that 8 of other 10 mutations may collectively contribute to impaired CK2 function. The broader significance of these findings is discussed.

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