Life Sciences Commons^™

A Nosy Neighbor: Purification And Functional Characterization Of Lpg2149, Ashley M. Holahan

The Journal of Purdue Undergraduate Research

Ubiquitination is a process that marks proteins for various cell-signaling pathways, namely protein degradation and other processes. Th ese pathways are essential in a wide array of cellular processes, including defense mechanisms against invading pathogens. Th e ubiquitination process is universally found in all eukaryotic organisms, including plants and animals, and thus plays a vital role in cellular homeostasis. Recently, more discoveries have been made on prokaryotic effector proteins that hijack the ubiquitination system even when they do not possess a ubiquitin system of their own. MavC, also known as lpg2147 (Gan, Nakayasu, Hollenbeck, & Luo, 2019; Puvar et al., …

Structural And Functional Characterization Of Hyper-Phosphorylated Grk5 Protein Expressed From E. Coli, Joseph M. Krampen, John Tesmer, Qiuyan Chen

The Summer Undergraduate Research Fellowship (SURF) Symposium

G protein-coupled receptor (GPCR) kinases (GRKs) are proteins in the cell responsible for regulating GPCRs located on the cell membrane. GRKs regulate active GPCRs by phosphorylating them at certain sites which causes them to stop normal signaling on the membrane. This ultimately affects how the cell responds to its environment. GRK5 is a kinase of particular interest due to its involvement in the pathology of diseases such as cardiac failure, cancers, and diabetes. Understanding the structure and function of GRK5 is essential for discovering ways to manipulate its behavior with these diseases, but not much is known about how GRK5 …

An Investigation Of Atomic Structures Derived From X-Ray Crystallography And Cryo-Electron Microscopy Using Distal Blocks Of Side-Chains, Lin Chen, Jing He, Salim Sazzed, Rayshawn Walker

Computer Science Faculty Publications

Cryo-electron microscopy (cryo-EM) is a structure determination method for large molecular complexes. As more and more atomic structures are determined using this technique, it is becoming possible to perform statistical characterization of side-chain conformations. Two data sets were involved to characterize block lengths for each of the 18 types of amino acids. One set contains 9131 structures resolved using X-ray crystallography from density maps with better than or equal to 1.5 Å resolutions, and the other contains 237 protein structures derived from cryo-EM density maps with 2-4 Å resolutions. The results show that the normalized probability density function of block …

Determining The Structure Of Phospholipase C Epsilon, Hannah O'Neill, Monita Sieng, Elisabeth Garland-Kuntz, Angeline Lyon

The Summer Undergraduate Research Fellowship (SURF) Symposium

The phospholipase C (PLC) epsilon subfamily of PLC enzymes are found at highest concentration within the cardiovascular system. Improper functioning of the enzyme, whether due to overstimulation or changes in expression, has far-reaching effects within the human body Stunted heart valve development and cardiac hypertrophy and are two such examples. The mechanisms by which PLC epsilon activity is regulated in these processes remain unknown, as does the physical structure of the enzyme. In this study, we seek to determine the structure of a PLC epsilon fragment that retains enzymatic activity and is amenable to crystallization. Mutagenesis of PLC epsilon cDNA …

Advances In Structural And Functional Analysis Of Membrane Proteins By Electron Crystallography, Goragot Wisedchaisri, Steve Reichow, Tamir Gonen

Chemistry Faculty Publications and Presentations

Electron crystallography is a powerful technique for the study of membrane protein structure and function in the lipid environment. When well-ordered two-dimensional crystals are obtained the structure of both protein and lipid can be determined and lipid-protein interactions analyzed. Protons and ionic charges can be visualized by electron crystallography and the protein of interest can be captured for structural analysis in a variety of physiologically distinct states. This review highlights the strengths of electron crystallography and the momentum that is building up in automation and the development of high throughput tools and methods for structural and functional analysis of membrane …

Novel Adaptor-Dependent Domains Promote Processive Degradation By Clpxp, Keith L. Rood

Masters Theses 1911 - February 2014

Protein degradation by ATP dependent proteases is a universally conserved process. Recognition of substrates by such proteases commonly occurs via direct interaction or with the aid of a regulatory adaptor protein. An example of this regulation is found in Caulobacter crescentus, where key regulatory proteins are proteolysed in a cell-cycle dependent fashion. Substrates include essential transcription factors, structural proteins, and second messenger metabolism components. In this study, we explore sequence and structural requirements for regulated adaptor mediated degradation of PdeA, an important regulator of cyclic-di-GMP levels.

Robust degradation of PdeA is dependent on the response regulator CpdR in vivo …

A Kinesin Motor In A Force-Producing Conformation, Elisabeth Heuston, C. Eric Bronner, F Jon Kull, Sharyn A. Endow

Dartmouth Scholarship

Kinesin motors hydrolyze ATP to produce force and move along microtubules, converting chemical energy into work by a mechanism that is only poorly understood. Key transitions and intermediate states in the process are still structurally uncharacterized, and remain outstanding questions in the field. Perturbing the motor by introducing point mutations could stabilize transitional or unstable states, providing critical information about these rarer states.

Capturing Hammerhead Ribozyme Structures In Action By Modulating General Base Catalysis, Young-In Chi, Monika Martick, Monica Lares, Rosalind Kim, William G. Scott, Sung-Hou Kim

Center for Structural Biology Faculty Publications

We have obtained precatalytic (enzyme-substrate complex) and postcatalytic (enzyme-product complex) crystal structures of an active full-length hammerhead RNA that cleaves in the crystal. Using the natural satellite tobacco ringspot virus hammerhead RNA sequence, the self-cleavage reaction was modulated by substituting the general base of the ribozyme, G12, with A12, a purine variant with a much lower pKa that does not significantly perturb the ribozyme's atomic structure. The active, but slowly cleaving, ribozyme thus permitted isolation of enzyme-substrate and enzyme-product complexes without modifying the nucleophile or leaving group of the cleavage reaction, nor any other aspect of the substrate. The predissociation …

A Subgroup Algorithm To Identify Cross-Rotation Peaks Consistent With Non-Crystallographic Symmetry, Ryan H. Lilien, Chris Bailey-Kellogg, Amy C. Anderson, Bruce R. Donald

Dartmouth Scholarship

Molecular replacement (MR) often plays a prominent role in determining initial phase angles for structure determination by X-ray crystallography. In this paper, an efficient quaternion-based algorithm is presented for analyzing peaks from a cross-rotation function in order to identify model orientations consistent with proper non-crystallographic symmetry (NCS) and to generate proper NCS-consistent orientations missing from the list of cross-rotation peaks. The algorithm, CRANS, analyzes the rotation differences between each pair of cross-rotation peaks to identify finite subgroups. Sets of rotation differences satisfying the subgroup axioms correspond to orientations compatible with the correct proper NCS. The CRANS algorithm was first …