Ask a Librarian

Threre are lots of ways to contact a librarian. Choose what works best for you.

HOURS TODAY

10:00 am - 4:00 pm

Reference Desk

CONTACT US BY PHONE

(802) 656-2022

Voice

(802) 503-1703

Text

MAKE AN APPOINTMENT OR EMAIL A QUESTION

Schedule an Appointment

Meet with a librarian or subject specialist for in-depth help.

Email a Librarian

Submit a question for reply by e-mail.

WANT TO TALK TO SOMEONE RIGHT AWAY?

Library Hours for Monday, June 17th

All of the hours for today can be found below. We look forward to seeing you in the library.
HOURS TODAY
8:00 am - 8:00 pm
MAIN LIBRARY

SEE ALL LIBRARY HOURS
WITHIN HOWE LIBRARY

Maps9:00 am - 4:30 am

Media Services8:00 am - 5:00 pm

Reference Desk10:00 am - 4:00 pm

Cyber Cafe (All Night Study)Closed

OTHER DEPARTMENTS

Special Collections10:00 am - 5:00 pm

Dana Medical Library7:30 am - 11:00 pm

Classroom Technology Services8:00 am - 4:30 pm

 

CATQuest

Search the UVM Libraries' collections

UVM Theses and Dissertations

Browse by Department
Format:
Print
Author:
Sheehe, Jessica Lynne
Dept./Program:
Cellular, Molecular and Biomedical Sciences Graduate Program
Year:
2018
Degree:
Ph.D.
Abstract:
The type I[alpha] cGMP-dependent protein kinase (PKG I[alpha]) is an essential regulator of vascular tone and systemic blood pressure. Located in the smooth muscle of resistance vessels, PKG I[alpha] stimulates vasodilation through the phosphorylation of multiple intracellular substrates. Its primary regulator is the small molecule, 3',5'-cyclic guanosine monophosphate (cGMP); however, the I[alpha] isoform can also be activated by oxidation. Despite the established physiological importance of PKG I[alpha], the structural underpinnings of these two activation mechanisms are largely unknown. The work presented in this dissertation demonstrates the importance of the cGMP-binding domain A (CBD-A) in regulating both of these mechanisms of PKG I[alpha] activation. Using a monomeric, N-terminally truncated form of PKG I[alpha] ([deltal]53), Chapter 2 investigates the mechanism of inhibition through the autoinhibitory domain and the influence of dimerization on cooperative cGMP-dependent activation and cyclic nucleotide selectivity. We observed that autoinhibition occurs in cis, whereas cooperativity requires interprotomer contacts facilitated by the N-terminal dimerization domain. Furthermore, the loss of selectivity for cGMP over cAMP of this construct suggests the dimerization domain plays a critical role in preventing cross-reactivity with cAMP-dependent signaling. These observations culminate into an overarching model wherein binding of cGMP to CBD-A is necessary and sufficient for activation and cooperativity is driven by the dimerization domain. Chapter 3 investigates the cysteine residues that mediate oxidation-dependent activation of PKG I[alpha]. Using PKG I[alpha] constructs with point mutations at specific cysteine residues, it was found that oxidation-dependent activation is driven by C117 in CBD-A. Furthermore, the interprotomer disulfide bond that forms in the dimerization domain at C42 does not contribute to this mechanism. Finally, we propose a model wherein the disulfide bond that forms between C117 and the adjacent cysteine at position 195 acts as a protective mechanism to prevent activation and higher oxidation states form contacts with nearby residues in the linker region of PKG I[alpha] to disrupt binding of the adjacent autoinhibitory domain to the catalytic domain. Finally, Chapter 4 provides a discussion of the results presented herein in context with previous studies and suggests future directions for the PKG field.