Allosteric Mechanism on DREAM Dimerization and Impact on Its Interactions with Divalent Metal Zn2+

Authors

Maria D. Santiago EstevezFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Chemistry

First Advisor's Name

Jaroslava Miksovska

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Xiaotang Wang

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Francisco Fernadez-Lima

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Fenfei Leng

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Prem Chapagain

Fifth Advisor's Committee Title

Committee member

Keywords

Neuronal Calcium Sensors, DREAM, calsenilin, potassium channels, divalent metals interactions, allostery

Date of Defense

6-29-2022

Abstract

DREAM belongs to the NCS family, and it is involved in several physiological processes mediated by Ca²⁺ association, which produces changes in its oligomerization state. The mechanism of how Ca²⁺ binds to DREAM remains unknown. A kinetic study of the binding of Ca²⁺ to DREAM suggested that DREAM dimerization is a two-step process, the first step( τ₁= 8±0.1ms) is associated with the binding of Ca²⁺ to the monomer, while the second step (τ₂ = 3.6 ±0.4 s ) corresponds to a conformation relaxation that leads to the dimerization. Furthermore, by analyzing the fast kinetic k _obsvs[L] , an inverse hyperbolic dependance was observed , which corresponds to the conformational selection mechanism providing crucial information on the binding of Ca²⁺ to DREAM.

Previous MD studies has shown that a network of hydrophobic residues in DREAM participate in the transmission of the interdomain allosteric signal. The Trp169 is part of this network, MD analysis were performed to determine its role in allosteric signal transmission. The mutation of Trp to Ala lead to a loss of structural rearrangement previously observed upon Ca²⁺ binding. For instance, in the case of DREAMW169A the stabilizing salt bridge K87-E165 was not present , the EF hands in the mutant did not undergo the reorientation observed in DREAMWT and the dimer divided into two monomers in the presence of Ca²⁺. These findings suggest the Trp169 is involved in the interdomain communication in DREAM, and it is crucial for the protein proper functioning.

Zn²⁺ is involved in several physiological processes and interacts with a wide variety of proteins , including other NCS proteins. DREAM also interacts with divalent metals with relatively high affinity . The presence of Zn²⁺ produces changes in DREM’s tertiary structure , and it is able to bind to DREAM in the presence(K_d=10.76± 1.46 and µM) and absence of Ca²⁺ (K_d=6.9 ± 0.6 µM). For the MD studies in the presence and absence of Ca²⁺, Zn²⁺ was found to bind to the protein involving amino acids located in EFH2. These findings suggest that Zn²⁺ may be involved in processes possibly involving DREAM and other NCS.

Identifier

FIDC010782

Recommended Citation

Santiago Estevez, Maria D., "Allosteric Mechanism on DREAM Dimerization and Impact on Its Interactions with Divalent Metal Zn2+" (2022). FIU Electronic Theses and Dissertations. 5033.
https://digitalcommons.fiu.edu/etd/5033