Medicinal-Pharmaceutical Chemistry Commons^™

The Reversible Low-Temperature Instability Of Human Dj-1 Oxidative States, Tessa Andrews, Javier Seravallic, Robert Powers

Robert Powers Publications

DJ-1 is a homodimeric protein that is centrally involved in various human diseases including Parkinson disease (PD). DJ-1 protects against oxidative damage and mitochondrial dysfunction through a homeostatic control of reactive oxygen species (ROS). DJ-1 pathology results from a loss of function, where ROS readily oxidizes a highly conserved and functionally essential cysteine (C106). The over-oxidation of DJ-1 C106 leads to a dynamically destabilized and biologically inactivated protein. An analysis of the structural stability of DJ-1 as a function of oxidative state and temperature may provide further insights into the role the protein plays in PD progression. NMR spectroscopy, circular …

Enhancing The Conformational Stability Of The Cl-Par-4 Tumor Suppressor Via Site-Directed Mutagenesis, Samjhana Pandey, Krishna K. Raut, Andrea M. Clark, Antoine Baudin, Lamya Djemri, David S. Libich, Komala Ponniah, Steven M. Pascal

Chemistry & Biochemistry Faculty Publications

Intrinsically disordered proteins play important roles in cell signaling, and dysregulation of these proteins is associated with several diseases. Prostate apoptosis response-4 (Par-4), an approximately 40 kilodalton proapoptotic tumor suppressor, is a predominantly intrinsically disordered protein whose downregulation has been observed in various cancers. The caspase-cleaved fragment of Par-4 (cl-Par-4) is active and plays a role in tumor suppression by inhibiting cell survival pathways. Here, we employed site-directed mutagenesis to create a cl-Par-4 point mutant (D313K). The expressed and purified D313K protein was characterized using biophysical techniques, and the results were compared to that of the wild-type (WT). We have …

Meta-Analysis Reveals Both The Promises And The Challenges Of Clinical Metabolomics, Heidi E. Roth, Robert Powers

Chemistry Department: Faculty Publications

Clinical metabolomics is a rapidly expanding field focused on identifying molecular biomarkers to aid in the efficient diagnosis and treatment of human diseases. Variations in study design, metabolomics methodologies, and investigator protocols raise serious concerns about the accuracy and reproducibility of these potential biomarkers. The explosive growth of the field has led to the recent availability of numerous replicate clinical studies, which permits an evaluation of the consistency of biomarkers identified across multiple metabolomics projects. Pancreatic ductal adenocarcinoma (PDAC) is the third-leading cause of cancer-related death and has the lowest five-year survival rate primarily due to the lack of an …

The Characterization Of A New Metabolite From A Trichodesmium Bloom, Kelly M. Mcmanus

Senior Honors Projects

Our laboratory has been investigating blooms of Trichodesmium, a genus of ecologically important, nitrogen-fixing cyanobacteria, collected from Padre Island in the Gulf of Mexico. Trichodesmium species are an underexplored biological source of cyanobacteria – a taxa that has been shown to produce chemically diverse secondary metabolites. With our focus on the isolation and structure characterization of new bioactive marine natural products, our research group has discovered over 25 new-to-science compounds over the past three years from these blooms. UV and mass spectrometry-guided isolation of Trichodesmium chromatography fractions were utilized to isolate a new metabolite. Isolation of this metabolite was …

Nmr Metabolomics Protocols For Drug Discovery, Fatema Bhinderwala, Robert Powers

Chemistry Department: Faculty Publications

Drug discovery is an extremely difficult and challenging endeavor with a very high failure rate. The task of identifying a drug that is safe, selective and effective is a daunting proposition because disease biology is complex and highly variable across patients. Metabolomics enables the discovery of disease biomarkers, which provides insights into the molecular and metabolic basis of disease and may be used to assess treatment prognosis and outcome. In this regard, metabolomics has evolved to become an important component of the drug discovery process to resolve efficacy and toxicity issues, and as a tool for precision medicine. A detailed …

Structural Basis Of 7sk Rna 5′ Γ-Phosphate Methylation And Retention By Mepce, Yuan Yang, Catherine D. Eichhorn, Yaqiang Wang, Duilio Cascio, Juli Feigon

Chemistry Department: Faculty Publications

Among RNA 5′-cap structures, γ-phosphate monomethylation is unique to a small subset of noncoding RNAs, 7SK and U6 in humans. 7SK is capped by methylphosphate capping enzyme (MePCE), which has a second non-enzymatic role as a core component of the 7SK RNP that is an essential regulator of RNA transcription. We report 2.0 and 2.1 Å X-ray crystal structures of human MePCE methyltransferase domain bound to S-adenosylhomocysteine (SAH) and uncapped or capped 7SK substrates, respectively. 7SK recognition is achieved by protein contacts to a 5′ hairpin-single-stranded RNA region, explaining MePCE specificity for 7SK and U6. The structures reveal SAH and …

Computational Modeling Of Rna-Small Molecule And Rna-Protein Interactions, Lu Chen

Dissertations & Theses (Open Access)

The past decade has witnessed an era of RNA biology; despite the considerable discoveries nowadays, challenges still remain when one aims to screen RNA-interacting small molecule or RNA-interacting protein. These challenges imply an immediate need for cost-efficient while predictive computational tools capable of generating insightful hypotheses to discover novel RNA-interacting small molecule or RNA-interacting protein. Thus, we implemented novel computational models in this dissertation to predict RNA-ligand interactions (Chapter 1) and RNA-protein interactions (Chapter 2).

Targeting RNA has not garnered comparable interest as protein, and is restricted by lack of computational tools for structure-based drug design. To test the potential …

Structure And Function Of Preq1 Riboswitches, Catherine D. Eichhorn, Mijeong Kang, Juli Feigon

Chemistry Department: Faculty Publications

PreQ₁ riboswitches help regulate the biosynthesis and transport of PreQ₁ (7-aminomethyl-7- deazaguanine), a precursor of the hypermodified guanine nucleotide queuosine (Q), in a number of Firmicutes, Proteobacteria, and Fusobacteria. Queuosine is almost universally found at the wobble position of the anticodon in asparaginyl, tyrosyl, histidyl and aspartyl tRNAs, where it contributes to translational fidelity. Two classes of PreQ₁ riboswitches have been identified (PreQ₁-I and PreQ₁-II), and structures of examples from both classes have been determined. Both classes form H-type pseudoknots upon PreQ₁ binding, each of which has distinct unusual features and modes …

Conformational Selection And Substrate Binding Regulate The Monomer/Dimer Equilibrium Of The C-Terminal Domain Of Escherichia Coli Enzyme I, Vincenzo Venditti, G. Marius Clore

Vincenzo Venditti

The bacterial phosphotransferase system (PTS) is a signal transduction pathway that couples phosphoryl transfer to active sugar transport across the cell membrane. The PTS is initiated by the binding of phosphoenolpyruvate (PEP) to the C-terminal domain (EIC) of enzyme I (EI), a highly conserved protein that is common to all sugar branches of the PTS. EIC exists in a dynamic monomer/dimer equilibrium that is modulated by ligand binding and is thought to regulate the overall PTS. Isolation of EIC has proven challenging, and conformational dynamics within the EIC domain during the catalytic cycle are still largely unknown. Here, we present …

Structure And Thermodynamics Of A Conserved U2 Snrna Domain From Yeast And Human, Dipali G. Sashital, Vincenzo Venditti, Courtney G. Angers, Gabriel Cornilescu, Samuel E. Butcher

Vincenzo Venditti

The spliceosome is a dynamic ribonucleoprotein complex responsible for the removal of intron sequences from pre-messenger RNA. The highly conserved 5′ end of the U2 small nuclear RNA (snRNA) makes key base-pairing interactions with the intron branch point sequence and U6 snRNA. U2 stem I, a stem–loop located in the 5′ region of U2, has been implicated in spliceosome assembly and may modulate the folding of the U2 and U6 snRNAs in the spliceosome active site. Here we present the NMR structures of U2 stem I from human and Saccharomyces cerevisiae. These sequences represent the two major classes of U2 …