Biochemistry, Biophysics, and Structural Biology Commons^™

Oxidative Stress, Metabolomics Profiling, And Mechanism Of Local Anesthetic Induced Cell Death In Yeast, Cory Honsinger Thomas Boone, Ryan A. Grove, Dana Adamcova, Javier Seravalli, Jiri Adamec

Department of Biochemistry: Faculty Publications

The World Health Organization designates lidocaine as an essential medicine in healthcare, greatly increasing the probability of human exposure. Its use has been associated with ROS generation and neurotoxicity. Physiological and metabolomic alterations, and genetics leading to the clinically observed adverse effects have not been temporally characterized. To study alterations that may lead to these undesirable effects, Saccharomyces cerevisiae grown on aerobic carbon sources to stationary phase was assessed over 6 h. Exposure of an LC₅₀ dose of lidocaine, increased mitochondrial depolarization and ROS/RNS generation assessed using JC-1, ROS/RNS specific probes, and FACS. Intracellular calcium also increased, assessed by …

Toxoplasma Dj-1 Regulates Organelle Secretion By A Direct Interaction With Calcium-Dependent Protein Kinase 1, Matthew A. Child, Megan Garland, Ian Foe, Peter Madzelan, Moritz Treeck, Wouter A. Van Der Linden, Kristina Oresic Bender, Evanthie Weerapana, Mark A. Wilson, John C. Boothroyd, Michael L. Reese

Department of Biochemistry: Faculty Publications

Human DJ-1 is a highly conserved and yet functionally enigmatic protein associated with a heritable form of Parkinson’s disease. It has been suggested to be a redox-dependent regulatory scaffold, binding to proteins to modulate their function. Here we present the X-ray crystal structure of the Toxoplasma orthologue Toxoplasma gondii DJ-1 (TgDJ-1) at 2.1-A resolution and show that it directly associates with calcium-dependent protein kinase 1 (CDPK1). The TgDJ-1 structure identifies an orthologously conserved arginine dyad that acts as a phospho-gatekeeper motif to control complex formation. We determined that the binding of TgDJ-1 to CDPK1 is sensitive to oxidation and calcium, …

Seasonal Switchgrass Ecotype Contributions To Soil Organic Carbon, Deep Soil Microbial Community Composition And Rhizodeposit Uptake During An Extreme Drought, Catherine E. Stewart, Damaris Roosendaal, Karolien Denef, Elizabeth Pruessner, Louise H. Comas, Gautam Sarath, Virginia L. Jin, Marty R. Schmer, Madhavan Soundararajan

Department of Biochemistry: Faculty Publications

The importance of rhizodeposit C and associated microbial communities in deep soil C stabilization is relatively unknown. Phenotypic variability in plant root biomass could impact C cycling through belowground plant allocation, rooting architecture, and microbial community abundance and composition. We used a pulse-chase ¹³C labeling experiment with compound-specific stable-isotope probing to investigate the importance of rhizodeposit C to deep soil microbial biomass under two switchgrass ecotypes (Panicum virgatum L., Kanlow and Summer) with contrasting root morphology. We quantified root phenology, soil microbial biomass (phospholipid fatty acids, PLFA), and microbial rhizodeposit uptake (¹³C-PLFAs) to 150 cm over …

Secs (Sinusoidal Endothelial Cells), Liver Microenvironment, And Fibrosis, Vaishaali Natarajan, Edward N. Harris, Srivatsan Kidambi

Department of Biochemistry: Faculty Publications

Liver fibrosis is awound-healing response to chronic liver injury such as alcoholic/nonalcoholic fatty liver disease and viral hepatitis with no FDA-approved treatments. Liver fibrosis results in a continual accumulation of extracellular matrix (ECM) proteins and paves the way for replacement of parenchyma with nonfunctional scar tissue. The fibrotic condition results in drastic changes in the local mechanical, chemical, and biological microenvironment of the tissue. Liver parenchyma is supported by an efficient network of vasculature lined by liver sinusoidal endothelial cells (LSECs). These nonparenchymal cells are highly specialized resident endothelial cell type with characteristic morphological and functional features. Alterations in LSECs …

Gene Duplication And Neo-Functionalization In The Evolutionary And Functional Divergence Of The Metazoan Copper Transporters Ctr1 And Ctr2, Brandon L. Logeman, L. Kent Wood, Jaekwoon Lee, Dennis J. Thiele

Department of Biochemistry: Faculty Publications

Copper is an essential element for proper organismal development and is involved in a range of processes, including oxidative phosphorylation, neuropeptide biogenesis, and connective tissue maturation. The copper transporter (Ctr) family of integral membrane proteins is ubiquitously found in eukaryotes and mediates the high-affinity transport of Cu_ across both the plasma membrane and endomembranes. Although mammalian Ctr¹ functions as a Cu_ transporter for Cu acquisition and is essential for embryonic development, a homologous protein, Ctr², has been proposed to function as a low-affinity Cu transporter, a lysosomal Cu exporter, or a regulator of Ctr¹ activity, but …

Carbon And Acyl Chain Flux During Stress-Induced Triglyceride Accumulation By Stable Isotopic Labeling Of The Polar Microalga Coccomyxa Subellipsoidea C169, James W. Allen, Concetta C. Dirusso, Paul N. Black

Department of Biochemistry: Faculty Publications

Deriving biofuels and other lipoid products from algae is a promising future technology directly addressing global issues of atmospheric CO₂ balance. To better understand the metabolism of triglyceride synthesis in algae, we examined their metabolic origins in the model species, Coccomyxa subellipsoidea C169, using stable isotopic labeling. Labeling patterns arising from [U-¹³C]glucose, ¹³CO₂, or D₂O supplementation were analyzed by GC-MS and/or LC-MS over time courses during nitrogen starvation to address the roles of catabolic carbon recycling, acyl chain redistribution, and de novo fatty acid (FA) synthesis during the expansion of the lipid …

Quantification Of Cell Signaling Networks Using Kinase Activity Chemosensors, Jon R. Beck, Edward N. Harris, Cliff I. Stains

Department of Biochemistry: Faculty Publications

The ability to directly determine endogenous kinase activity in tissue homogenates provides valuable insights into signaling aberrations that underlie disease phenotypes. When activity data is collected across a panel of kinases, a unique “signaling fingerprint” is generated that allows for discrimination between diseased and normal tissue. Here we describe the use of peptide-based kinase activity sensors to fingerprint the signaling changes associated with disease states. This approach leverages the phosphorylation-sensitive sulfonamido-oxine (Sox) fluorophore to provide a direct readout of kinase enzymatic activity in unfractionated tissue homogenates from animal models or clinical samples. To demonstrate the application of this technology, we …

The Intestinal Copper Exporter Cua-1 Is Required For Systemic Copper Homeostasis In Caenorhabditis Elegans, Haarin Chun, Anuj Kumar Sharma, Jaekwon Lee, Jefferson Chan, Shang Jia, Byung-Eun Kim

Department of Biochemistry: Faculty Publications

Copper plays key catalytic and regulatory roles in biochemical processes essential for normal growth, development, and health. Defects in copper metabolism cause Menkes and Wilson’s disease, myeloneuropathy, and cardiovascular disease and are associated with other pathophysiological states. Consequently, it is critical to understand the mechanisms by which organisms control the acquisition, distribution, and utilization of copper. The intestinal enterocyte is a key regulatory point for copper absorption into the body; however, the mechanisms by which intestinal cells transport copper to maintain organismal copper homeostasis are poorly understood. Here, we identify a mechanism by which organismal copper homeostasis is maintained by …

Structural Determinants Allowing Transferase Activity In Sensitive To Freezing 2, Classified As A Family I Glycosyl Hydrolase, Rebecca Roston, Kun Wang, Leslie A. Kuhn, Christoph Benning

Department of Biochemistry: Faculty Publications

Background: SENSITIVE TO FREEZING 2 (SFR2) is classified as a glycosyl hydrolase, and by using glycosyltransferase activity, it modifies membrane lipids to promote freeze tolerance.

Results: Although the active site of SFR2 is identical to hydrolases, adjacent loop regions contribute to its transferase activity.

Conclusion: Transferase activity evolved by modifications external to the core catalytic site.

Significance: Defined structure-function relationships will inform engineering of transferases and freeze tolerance.

Sending Out An Sos: Mitochondria As A Signaling Hub, Iryna Bohovych, Oleh Khalimonchuk

Department of Biochemistry: Faculty Publications

Normal cellular physiology is critically dependent on numerous mitochondrial activities including energy conversion, cofactor and precursor metabolite synthesis, and regulation of ion and redox homeostasis. Advances in mitochondrial research during the last two decades provide solid evidence that these organelles are deeply integrated with the rest of the cell and multiple mechanisms are in place to monitor and communicate functional states of mitochondria. In many cases, however, the exact molecular nature of various mitochondria-to-cell communication pathways is only beginning to emerge. Here, we review various signals emitted by distressed or dysfunctional mitochondria and the stress-responsive pathways activated in response to …

Loss Of Exogenous Androgen Dependence By Prostate Tumor Cells Is Associated With Elevated Glucuronidation Potential, Brenna M. Zimmer, Michelle E. Howell, Qin Wei, Linlin Ma, Trevor Romsdahl, Eileen G. Loughman, Jennifer E. Markham, Javier Seravalli, Joseph J. Barycki, Melanie A. Simpson

Department of Biochemistry: Faculty Publications

Prostate epithelial cells control the potency and availability of androgen hormones in part by inactivation and elimination. UDP-glucose dehydrogenase (UGDH) catalyzes the NAD⁺-dependent oxidation of UDP-glucose to UDP-glucuronate, an essential precursor for androgen inactivation by the prostate glucuronidation enzymes UGT2B15 and UGT2B17. UGDH expression is androgen stimulated, which increases the production of UDP-glucuronate, and fuels UGT-catalyzed glucuronidation. In this study, we compared the glucuronidation potential and its impact on androgen-mediated gene expression in an isogenic LNCaP model for androgen dependent versus castration resistant prostate cancer. Despite significantly lower androgen-glucuronide output, LNCaP 81 castration resistant tumor cells expressed higher …

Small-Angle X-Ray Scattering Studies Of The Oligomeric State And Quaternary Structure Of The Trifunctional Proline Utilization A (Puta) Flavoprotein From Escherichia Coli, Ranjan K. Singh, John D. Larson, Weidong Zhu, Robert P. Rambo, Greg L. Hura, Donald F. Becker, John J. Tanner

Department of Biochemistry: Faculty Publications

Background: Trifunctional proline utilization A (PutA) proteins are multifunctional flavoproteins that catalyze two reactions and repress transcription of the put regulon.

Results: PutA from Escherichia coli is a V-shaped dimer, with the DNA-binding domain mediating dimerization.

Conclusion: Oligomeric state and quaternary structures are not conserved by PutAs.

Significance: The first three-dimensional structural information for any trifunctional PutA is reported.

Methods For Detecting Microbial Methane Production And Consumption By Gas Chromatography, Jared T. Aldridge, Jennie L. Catlett, Megan L. Smith, Nicole R. Buan

Department of Biochemistry: Faculty Publications

Methane is an energy-dense fuel but is also a greenhouse gas 25 times more detrimental to the environment than CO2. Methane can be produced abiotically by serpentinization, chemically by Sabatier or Fisher-Tropsh chemistry, or biotically by microbes (Berndt et al., 1996; Horita and Berndt, 1999; Dry, 2002; Wolfe, 1982; Thauer, 1998; Metcalf et al., 2002). Methanogens are anaerobic archaea that grow by producing methane gas as a metabolic byproduct (Wolfe, 1982; Thauer, 1998). Our lab has developed and optimized three different gas chromatograph-utilizing assays to characterize methanogen metabolism (Catlett et al., 2015). Here we describe the end point and kinetic …

Stabilin-1 And Stabilin-2 Are Specific Receptors For The Cellular Internalization Of Phosphorothioate-Modified Antisense Oligonucleotides (Asos) In The Liver, Colton M. Miller, Aaron J. Donnerr, Emma E. Blank, Andrew W. Egger, Brianna M. Kellar, Michael E. Østergaard, Punit P. Seth, Edward N. Harris

Department of Biochemistry: Faculty Publications

Phosphorothioate (PS)-modified antisense oligonucleotides (ASOs) have been extensively investigated over the past three decades as pharmacological and therapeutic agents. One second generation ASO, Kynamro^TM, was recently approved by the FDA for the treatment of homozygous familial hypercholesterolemia and over 35 second generation PS ASOs are at various stages of clinical development. In this report, we show that the Stabilin class of scavenger receptors, which were not previously thought to bind DNA, do bind and internalize PS ASOs. With the use of primary cells from mouse and rat livers and recombinant cell lines each expressing Stabilin-1 and each isoform …

Nitrogenase Femoco Investigated By Spatially Resolved Anomalous Dispersion Refinement, Thomas Spatzal, Julia Schlesier, Eva-Maria Burger, Daniel Sippel, Limei Zhang, Susana L.A. Andrade, Douglas C. Rees, Oliver Einsle

Department of Biochemistry: Faculty Publications

The [Mo:7Fe:9S:C] iron-molybdenum cofactor (FeMoco) of nitrogenase is the largest known metal cluster and catalyses the 6-electron reduction of dinitrogen to ammonium in biological nitrogen fixation. Only recently its atomic structure was clarified, while its reactivity and electronic structure remain under debate. Here we show that for its resting S 1⁄4 3/2 state the common iron oxidation state assignments must be reconsidered. By a spatially resolved refinement of the anomalous scattering contributions of the 7 Fe atoms of FeMoco, we conclude that three irons (Fe1/3/7) are more reduced than the other four (Fe2/4/5/6). Our data are in agreement with the …

Role Of Apoptotic Hepatocytes In Hcv Dissemination: Regulation By Acetaldehyde, Murali Ganesan, Sathish Kumar Natarajan, Jinjin Zhang, Justin L. Mott, Larisa I. Poluektova, Benita L. Mcvicker, Kusum K. Kharbanda, Dean J. Tuma, Natalie A. Osna

Department of Biochemistry: Faculty Publications

Alcohol consumption exacerbates hepatitis C virus (HCV) pathogenesis and promotes disease progression, although the mechanisms are not quite clear. We have previously observed that acetaldehyde (Ach) continuously produced by the acetaldehyde-generating system (AGS), temporarily enhanced HCV RNA levels, followed by a decrease to normal or lower levels, which corresponded to apoptosis induction. Here, we studied whether Ach-induced apoptosis caused depletion of HCV-infected cells and what role apoptotic bodies (AB) play in HCV-alcohol crosstalk. In liver cells exposed to AGS, we observed the induction of miR-122 and miR-34a. As miR-34a has been associated with apoptotic signaling and miR-122 with HCV replication, …

Inhibition Of Protein Ubiquitination By Paraquat And 1-Methyl-4-Phenylpyridinium Impairs Ubiquitin-Dependent Protein Degradation Pathways, Juliana Navarro-Yepes, Anandhan Annadurai, Erin Bradley, Iryna Bohovych, Bo Yarabe, Annemieke De Jong, Huib Ovaa, You Zhou, Oleh Khalimonchuk, Betzabet Quintanilla-Vega, Rodrigo Franco

Department of Biochemistry: Faculty Publications

Intracytoplasmic inclusions of protein aggregates in dopaminergic cells (Lewy bodies) are the pathological hallmark of Parkinson’s disease (PD). Ubiquitin (Ub), alpha [α]-synuclein, p62/sequestosome 1 and oxidized proteins are major components of Lewy bodies. However, the mechanisms involved in the impairment of misfolded/oxidized protein degradation pathways in PD are still unclear. PD is linked to mitochondrial dysfunction and environmental pesticide exposure. In this work, we evaluated the effect of the pesticide paraquat (PQ) and the mitochondrial toxin 1-methyl-4-phenylpyridinium (MPP⁺) on Ub-dependent protein degradation pathways. No increase in the accumulation of Ub-bound proteins or aggregates was observed in dopaminergic cells …

Tumor Suppressive Role Of Sestrin2 During Colitis And Colon Carcinogenesis, Seung-Hyun Ro, Xiang Xue, Sadeesh K. Ramakrishnan, Chun-Seok Cho, Sim Namkoong, Insook Jang, Ian A. Semple, Allison Ho, Hwan-Woo Park, Yatrik M. Shah, Jun Hee Lee

Department of Biochemistry: Faculty Publications

The mTOR complex 1 (mTORC1) and endoplasmic reticulum (ER) stress pathways are critical regulators of intestinal inflammation and colon cancer growth. Sestrins are stress-inducible proteins, which suppress both mTORC1 and ER stress; however, the role of Sestrins in colon physiology and tumorigenesis has been elusive due to the lack of studies in human tissues or in appropriate animal models. In this study, we show that human SESN2 expression is elevated in the colon of ulcerative colitis patients but is lost upon p53 inactivation during colon carcinogenesis. In mouse colon, Sestrin2 was critical for limiting ER stress and promoting the recovery …

Potassium And The K+/H+ Exchanger Kha1p Promote Binding Of Copper To Apofet3p Multi-Copper Ferroxidase, Xiaobin Wu, Heejeong Kim, Javier Seravalli, Joseph J. Barycki, P. John Hart, David W. Gohara, Enrico Di Cera, Won Hee Jung, Daniel J. Kosman, Jaekwon Lee

Department of Biochemistry: Faculty Publications

Acquisition and distribution of metal ions support a number of biological processes. Here we show that respiratory growth of and iron acquisition by the yeast Saccharomyces cerevisiae relies on potassium (K⁺) compartmentalization to the trans-Golgi network via Kha1p, a K⁺/H⁺ exchanger. K⁺ in the trans-Golgi network facilitates binding of copper to the Fet3p multi-copper ferroxidase. The effect of K⁺ is not dependent on stable binding with Fet3p or alteration of the characteristics of the secretory pathway. The data suggest that K⁺ acts as a chemical factor in Fet3p maturation, a …

Analysis Of Oligomerization Properties Of Heme A Synthase Provides Insights Into Its Function In Eukaryotes, Samantha Swenson, Andrew Cannon, Nicholas J. Harris, Nicholas G. Taylor, Jennifer L. Fox, Oleh Khalimonchuk

Department of Biochemistry: Faculty Publications

Heme a is an essential cofactor for function of cytochrome c oxidase in the mitochondrial electron transport chain. Several evolutionarily conserved enzymes have been implicated in the biosynthesis of heme a, including the heme a synthase Cox15. However, the structure of Cox15 is unknown, its enzymatic mechanism and the role of active site residues remain debated, and recent discoveries suggest additional chaperone-like roles for this enzyme. Here, we investigated Cox15 in the model eukaryote Saccharomyces cerevisiae via several approaches to examine its oligomeric states and determine the effects of active site and human pathogenic mutations. Our results indicate that Cox15 …

Alcoholic Vs Non-Alcoholic Fatty Liver In Rats: Distinct Differences In Endocytosis And Vesicle Trafficking Despite Similar Pathology, Karuna Rasineni, Daniel D. Penrice, Sathish Kumar Natarajan, Mark A. Mcniven, Benita L. Mcvicker, Kusum K. Kharbanda, Carol A. Casey, Edward N. Harris

Department of Biochemistry: Faculty Publications

Background: Non-alcoholic and alcoholic fatty liver disease (NAFLD and AFLD, respectively) are major health problems, as patients with either condition can progress to hepatitis, fibrosis, and cirrhosis. Although histologically similar, key differences likely exist in these two models. For example, altered content of several vesicle trafficking proteins have been identified in AFLD, but their content in NAFLD is unknown. In this study, we compared select parameters in NAFLD and AFLD in a rat model.

Methods: We fed either Lieber- DeCarli liquid control or alcohol-containing (35 % as calories) diet (AFLD model) or lean or high-fat (12 or 60 % derived …

Atomic Resolution Experimental Phase Information Reveals Extensive Disorder And Bound 2-Methyl-2,4-Pentanediol In Ca2+-Calmodulin, Jiusheng Lin, Henry Van Den Bedem, Axel T. Brunger, Mark A. Wilson

Department of Biochemistry: Faculty Publications

Calmodulin (CaM) is the primary calcium signaling protein in eukaryotes and has been extensively studied using various biophysical techniques. Prior crystal structures have noted the presence of ambiguous electron density in both hydrophobic binding pockets of Ca²⁺-CaM, but no assignment of these features has been made. In addition, Ca²⁺-CaM samples many conformational substates in the crystal and accurately modeling the full range of this functionally important disorder is challenging. In order to characterize these features in a minimally biased manner, a 1.0 A resolution single-wavelength anomalous diffraction data set was measured for selenomethionine-substituted Ca²⁺-CaM. …

An Evaluation Of New And Established Methods To Determine T-Dna Copy Number And Homozygosity In Transgenic Plants, Katarzyna Glowacka, Johannes Kromdijk, Lauriebeth Leonelli, Krishna K. Niyogi, Tom E. Clemente, Stephen P. Long

Department of Biochemistry: Faculty Publications

Stable transformation of plants is a powerful tool for hypothesis testing.Arapid and reliable evaluation method of the transgenic allele for copy number and homozygosity is vital in analysing these transformations.Here the suitability of Southern blot analysis, thermal asymmetric interlaced (TAIL-)PCR, quantitative (q)PCR and digital droplet (dd)PCR to estimate T-DNA copy number, locus complexity and homozygosity were compared in transgenic tobacco. Southern blot analysis and ddPCR on three generations of transgenic offspring with contrasting zygosity and copy number were entirely consistent, whereas TAIL-PCR often underestimated copy number. qPCR deviated considerably from the Southern blot results and had lower precision and higher …

Pluralistic And Stochastic Gene Regulation: Examples, Models And Consistent Theory, Elisa N. Salas, Jiang Shu, Matyas F. Cserhati, Donald P. Weeks, Istvan Ladunga

Department of Biochemistry: Faculty Publications

We present a theory of pluralistic and stochastic gene regulation. To bridge the gap between empirical studies and mathematical models, we integrate pre-existing observations with our meta-analyses of the ENCODE ChIP-Seq experiments. Earlier evidence includes fluctuations in levels, location, activity, and binding of transcription factors, variable DNA motifs, and bursts in gene expression. Stochastic regulation is also indicated by frequently subdued effects of knockout mutants of regulators, their evolutionary losses/gains and massive rewiring of regulatory sites. We report wide-spread pluralistic regulation in ≈800 000 tightly co-expressed pairs of diverse human genes. Typically, half of ≈50 observed regulators bind to both …

Systems Perturbation Analysis Of A Large-Scale Signal Transduction Model Reveals Potentially Influential Candidates For Cancer Therapeutics, Bhanwar Lal Puniya, Laura Allen, Colleen Hochfelde, Mahbubul Majumder, Tomáš Helikar

Department of Biochemistry: Faculty Publications

Dysregulation in signal transduction pathways can lead to a variety of complex disorders, including cancer. Computational approaches such as network analysis are important tools to understand system dynamics as well as to identify critical components that could be further explored as therapeutic targets. Here, we performed perturbation analysis of a large-scale signal transduction model in extracellular environments that stimulate cell death, growth, motility, and quiescence. Each of the model's components was perturbed under both loss-of-function and gain-of-function mutations. Using 1,300 simulations under both types of perturbations across various extracellular conditions, we identified the most and least influential components based on …

Activation Of Erk And Nf-Κb During Hare-Mediated Heparin Uptake Require Only One Of The Four Endocytic Motifs, Madhu S. Pandey, Colton M. Miller, Edward N. Harris, Paul H. Weigel

Department of Biochemistry: Faculty Publications

Fifteen different ligands, including heparin (Hep), are cleared from lymph and blood by the Hyaluronan (HA) Receptor for Endocytosis (HARE; derived from Stabilin-2 by proteolysis), which contains four endocytic motifs (M1-M4). Endocytosis of HARE•Hep complexes is targeted to coated pits by M1, M2, and M3 (Pandey et al, Int. J. Cell Biol. 2015, article ID 524707), which activates ERK1/2 and NF-κB (Pandey et al J. Biol. Chem. 288, 14068–79, 2013). Here, we used a NF-κB promoter-driven luciferase gene assay and cell lines expressing different HARE cytoplasmic domain mutants to identify motifs needed for Hepmediated signaling. Deletion of M1, M2 or …