Molecular genetics; Protein Function and Structure; DNA Replication, Recombination and Repair; Bacterial Pathogenesis
My associates and I use a combination of biochemical and biophysical approaches to study the molecular basis of stalled DNA replication fork rescue. Our model organism is the well-characterized bacterium Escherichia coli (E. coli), since the majority of the proteins thought to be involved in fork rescue are known. Most of our experimental work is concerned with the function and regulation of the complexes that control fork rescue, with studies focused primarily on the role of the single-strand DNA binding protein (SSB) and several recombination DNA helicases. Comparative studies are also underway using selected components of some medically relevant bacterial organisms. We collaborate with scientists from the National Institutes of Health (NIH) and other research institutions. The team working in my lab consists of undergraduate and graduate students, postdoctoral fellows and a technician. We seek to understand fork rescue utilizing both bulk-phase and single molecule techniques. Typically, studies focus initially on purification and characterization of the various proteins (there are now more than 10 being studied). We study DNA binding, unwinding and the hydrolysis of adenosine triphosphate (ATP) using a combination of modern spectroscopic (both ultraviolet–visible and fluorescence) and equilibrium binding methods. The goal of these initial studies is to understand the range of DNA substrates on which an enzyme can act, as a means to understanding its role in vivo. This is followed by careful single molecule studies using a technique I pioneered that combines optical tweezers, microfluidics and high-resolution fluorescence microscopy. My research team is also pursuing a new area of research targeted at developing small molecule inhibitors. These are aimed at disrupting binding between SSB and the 12-14 proteins comprising the SSB-interactome. As SSB is an essential protein and its binding to interactome partners is required for viability, the goal of these studies is to identify inhibitors that will be further developed into novel antibiotics.
Allergy and Immunology; Medical Microbiology; Infectious Disease; Microbiology; Genomics and proteomics; Immunology; Microbial Pathogenesis; Molecular and Cellular Biology; Molecular Basis of Disease; Molecular genetics; Gene Expression; Signal Transduction; Protein Function and Structure; Bacterial Pathogenesis
Research efforts in my laboratory are focused in the fields of immunology and bacterial pathogenesis, two diverse fields of biomedical research for which I have two separate research groups. Projects in both fields are performed by undergraduates, doctoral and master’s degree students, postdoctoral fellows and senior research associates. One major focus of my laboratory is studying the regulation of mucosal immune responses. We investigate the cellular and molecular events by which Type II heat-labile enterotoxins (HLTs), produced by certain strains of Escherichia coli, modulate immune responses. We have demonstrated that LT-Ilia, LT-IIb and LT-IIc, when co-administered with an antigen, have the capacity to enhance antibody and cellular immune responses to that antigen. Using a variety of immunological and cellular technologies, including flow cytometry, fluorescence resonance energy transfer (FRET) detection, cytokine multiplex analysis, mutagenesis, quantitative Reverse Transcription PCR (qRT-PCR), RNA-sequencing (RNA-Seq) and a variety of transgenic mice, we are investigating the mechanisms by which these immunomodulators productively interact with various immunocompetent cells (T cells, B cells, dendritic cells, macrophages) to induce or suppress cytokine production, costimulatory ligand expression and cellular proliferation. A practical outgrowth of these experiments is the potential to engineer novel recombinant vaccines by genetically fusing antigens from different pathogens to the enterotoxins. Recent experiments have shown that these HLT are lethal for triple-negative breast cancer cells, which has opened a new area of oncological research for the lab. A second focus of my laboratory is to investigate the molecular mechanisms by which adherent-invasive Escherichia coli (AIEC) induce, exacerbate or prolong the symptoms of inflammatory bowel disease (IBD) and Crohn’s disease, two acute and chronic inflammatory diseases of the human gut. In vitro, AIEC strains invade into the cytoplasm of several epithelial cell lines. Using recombinant screening methods and RNA-Seq technologies, we are identifying the genes of AIEC that are required to attach and to invade gut cells.
Protein Function and Structure; Proteins and metalloenzymes; Vitamins and Trace Nutrient
Cytochrome P450 enzymes are ubiquitous catalysts that play integral roles in biochemical pathways throughout nature. In mammals, members of this class of enzyme serve a variety of functions that include drug metabolism, steroid biosynthesis and the activation and deactivation of vitamin D, to name a few. Cytochrome P450 enzymes are also heavily involved in bacterial and plant biochemistry. The overall goal of my lab is to use a combination of biochemical and biophysical tools to investigate structure and function in cytochrome P450 enzymes, thereby contributing toward an understanding of how this important class of enzymes work as well as informing the design of novel drugs. This goal is divided between two efforts. First, we are interested in characterizing the ligand binding interactions of the enzyme CYP24A1, the principle enzyme responsible for deactivating vitamin D. Describing the interaction between CYP24A1 and vitamin D has the potential to illuminate how the vitamin D structure becomes modified at a particular site. This insight could impact the design of vitamin D analogs with benefits for an array of human health conditions, including bone density disorders, diabetes and chronic kidney disease (CKD). A parallel effort in my lab is a structural study of the enzyme CYP121 of Mycobacterium tuberculosis, the disease-causing pathogen in tuberculosis (TB). The resurgence of standard TB and the rise of drug-resistant forms of TB are quickly becoming a global pandemic, with TB claiming more lives worldwide in 2014 than HIV. CYP121 is essential for survival of the bacterium and thus has emerged as one of the more promising antitubercular drug targets. Students and postdocs joining my lab will be exposed to a multidisciplinary set of research tools, including expression and purification of recombinant membrane protein, nuclear magnetic resonance, protein X-ray crystallography and P450 ligand binding assays.
Cell growth, differentiation and development; Molecular Basis of Disease; Proteins and metalloenzymes; Gene Expression; Inherited Metabolic Disorders; Protein Function and Structure; Cell Cycle
Protein Methylation in Growth and Differentiation. Protein methylation was recently found by systems biology approaches to play a major role in regulating yeast cell growth. Consistent with this finding, we found that disruption of the gene encoding S-adenosylhomocysteine (SAH1) hydrolase markedly inhibited growth. S-adenosylmethionine (SAM) is the universal methyl donor,and SAH1 is the product of all methyltransferase(MTase) reactions.The SAH1 disruption leads to a 50% decrease in protein synthesis which,in turn leads to major decreases in the levels of Cln3p.Unexpectedly,when cells were transfected with a modified gene for Cln3 ,that desreased its rate of degradation,growth rates were normal.This result was unexpected because the basic defect of lacking SAH1 remained.We are currently testing the hypothesis that normal rates of growth are due to increased gene expression for multiple enzymes known to be involved in Met and SAM synthesis. We are also identifying substrates for specific MTases in yeast. Copper deficiency is known to affect brain development, and Menkes disease is fatal due to impaired brain development from low brain copper. A reduction in (SAH1) levels, as occurs in copper deficiency, may affect brain development by inhibiting protein methylation.We demonstrated that inhibiting SAH1 maredly inhibited development of two nerve cell models.
Neuroimmunology; Behavioral pharmacology; Gene therapy; Immunology; Molecular and Cellular Biology; Molecular Basis of Disease; Neurobiology; Gene Expression; Signal Transduction; Protein Function and Structure; Neuropharmacology
My research spans three interrelated fields: chronic pain, depression and inflammation. Experiments in my laboratory focus on how brain-derived pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF), function as modulators of brain-body interactions during neuropathic pain and how brain-TNF is involved in the mechanism of action of antidepressant drugs. My overall goal is to advance knowledge of, and therapeutic efficacy for pain, depression, neuro-inflammation and drug addiction. This research is based on my earlier work showing that neurons produce the pro-inflammatory cytokine TNF and that the production of TNF by macrophages is regulated by neurotransmitters. Cytokines and neurotransmitters are principal signaling molecules that mediate bidirectional communication between the nervous and immune systems--the crosstalk important in maintaining homeostasis. Consequently, aberrant production of either of these two classes of mediators could profoundly affect signaling by the other, thereby impacting health. A shift in balanced cytokine-neuron interactions that regulate neurotransmitter release in the central nervous system (CNS), and that have potential behavioral consequences, manifest themselves as states of depression and chronic pain. My research uses both cell systems and animal models to test these hypotheses. Colleagues and I use a combination of imaging techniques to localize cytokine production, bioassays and ELISA (enzyme-linked immunosorbent assays) for pharmacological and functional analyses, electrophysiological (brain slice stimulation) and molecular methods for our studies. In addition to investigating neuron functioning in the brain, trainees in my laboratory also study the peripheral macrophage, a major source of TNF during inflammation. Specifically studying neurotransmitter regulation of TNF production in the periphery is enhancing our knowledge of how the brain controls a peripheral inflammatory lesion. Our studies are designed to investigate the mechanisms of centrally mediated pain as associated with immune dysfunction and to elucidate mechanisms of drugs used to treat such pain states. My projects are evolving to investigate the mechanisms and neural pathways involved in TNF neuromodulator functions during chronic pain (due to peripheral nerve injury and diabetes) and stress-induced depressive behavior. We also study mechanisms contributing to the comorbidity of chronic pain and depression. I collaborate with researchers in several UB departments and at other institutions. Our projects include using noninvasive methods for delivery of anti-TNF therapeutics for chronic pain, elucidating the neural-immune mechanisms involved in the rapid recovery afforded by centrally administered anti-TNF therapy and using nanotechnology-mediated, targeted gene silencing within the CNS. I am invested in helping my undergraduate and graduate students, medical residents and postdoctoral fellows realize their potential and achieve their goals. Previous students have advanced professionally and hold clinical, academic and industrial positions.
Genomics and proteomics; Protein Function and Structure; Proteins and metalloenzymes
The Malkowski Laboratory is focused on understanding the structure and function of integral membrane enzymes involved in the conversion of lipid precursors into potent bioactive signaling molecules. We utilize a myriad of methods and techniques to characterize these enzymes, including X-ray crystallography, electron spin resonance spectroscopy, protein chemistry, biochemistry, molecular biology, cell biology, and kinetics.
Gene Expression; Molecular Basis of Disease; Molecular and Cellular Biology; Molecular genetics; Protein Function and Structure; Transcription and Translation
Our laboratory utilizes combined genetic, biochemical and molecular biological approaches to investigate the molecular mechanisms involved in the initiation and regulation of eukaryotic transcription. Previous work in our laboratory utilizing both the budding yeast Saccharomyces cerevisiae and human cells resulted in the identification and biochemical characterization of mutants of nuclear RNA polymerase II (RNAPII) and the general transcription factors TFIIB and TFIIF that coordinately affect transcription start site utilization and transcript elongation. These studies supported a model where yeast and human TFIIF induce global conformational changes in RNAPII that result in structural and functional changes in the polymerase active center. Our current studies are focused on elucidating the mechanisms of kinetoplast transcription by the mitochondrial RNA polymerase of Trypanosoma brucei. T. brucei is a protozoan parasite that is the causative agent of African sleeping sickness (trypanosomiasis) in humans and nagana in animals. Procyclic trypanosomes growing in the midgut of the tsetse fly have a fully functional mitochondrion whereas trypanosomes in the mammalian bloodstream exhibit repressed mitochondrial function. The mitochondrial DNA in trypanosomes is unusual in its structure, comprising a highly catenated network of maxicircles and minicircles termed kinetoplast DNA (kDNA). Surprisingly, very little is known about the cis-acting elements and the trans-acting factors governing the transcription of maxicircles and minicircles. Our objective is to elucidate the mechanisms and regulation of T. brucei kDNA transcription with the ultimate goal of developing therapeutic agents.
Neurodegenerative disorders; Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular Basis of Disease; Signal Transduction; Protein Function and Structure; Neuropharmacology
I focus my research on the activation mechanisms of fast neurotransmitter receptors. We seek to define the activation pathway, modulatory mechanisms and structure-function relationships of the N-methyl-D-aspartate (NMDA) receptor to better understand the roles played by this protein in the brain. NMDA receptors are the most abundant glutamate-stimulated, Ca2+-conducting ion channels in brain and spinal cord. They are the predominant molecular devices for controlling synaptic development and plasticity and govern memory and learning processes. Understanding the mechanisms that control their activity may lead to more effective strategies to treat neuropathies including stroke, neurodegenerative conditions, chronic pain and addiction as well as mental disorders such as schizophrenia and epilepsy.
Ion channel kinetics and structure; Membrane Transport (Ion Transport); Molecular Basis of Disease; Molecular and Cellular Biology; Protein Folding; Protein Function and Structure; Signal Transduction
Work in my lab seeks to elucidate the transduction mechanisms of ion channels involved in thermal sensation and pain, such as the heat-activated vanilloid receptors (TRPV1-4) and the cold-activated TRPM8 – the so-called thermal TRP channels. Expressed in peripheral afferent nerve endings, these channels function as an array of thermometers for sensing ambient temperature from noxious cold to noxious hot. While all proteins are thermally sensitive, thermal TRP channels are gated by temperature and possess unprecedentedly high temperature dependence. But the mechanisms of their temperature gating has remained mysterious, in contrast to our abundant knowledge on other types of ion channel gating (e.g. voltage or ligand-driven). Thermal TRP channels are also distinct for their polymodal responsiveness. TRPV1, for example, is responsive to heat, voltage, pH, capsaicin (i.e. the hot ingredient of chili peppers) among many other irritant compounds. The channels are thus informative for deciphering how biological proteins achieve multitasking. Thermal TRP channels also have receptor-like roles in mediating intracellular signaling. The calcium influx through the channels has potentially a broad spectrum of functional consequences, one of which is the desensitization of the channels themselves, a phenomenon that is believed to underlie peripheral analgesics. Our research is centered on problems like these, and we approach them by a combination of techniques such as recombinant mutagenesis, patch-clamp recording, fluorescence measurements, quantitative modeling, etc, which together allow us to draw insights into functions of the channels at mechanistic levels. Complementing our experimental studies, we are also interested in development of methodology to ever extend experimental resolutions. For example, to time-resolve temperature-dependent activation of thermal TRP channels, we have developed a laser diode-based temperature clamp apparatus, which achieves for the first time a submillisecond resolution (>105 oC/s) while capable of clamping temperature constant. For the past decade we have also been developing sophisticated algorithms for statistical analysis of single-molecule measurements such as single-channel patch-clamp recordings, which can help unravel the richness of data pertaining to molecular mechanisms at high resolutions. Together, these approaches provide us with unique abilities for in-depth studies of structure-mechanisms of ion channels.
Eukaryotic Pathogenesis; Gene Expression; Genomics and proteomics; Infectious Disease; Microbial Pathogenesis; Microbiology; Molecular and Cellular Biology; Molecular genetics; Protein Function and Structure; RNA
Trypanosoma brucei is a eukaryotic pathogen that causes human African trypanosomiasis, a disease that is invariably fatal if not treated. Essential and novel processes in this parasite may serve as starting platforms for new chemotherapeutics, which are urgently needed. Our laboratory combines biochemical, genetic, genomic and proteomic approaches toward understanding gene regulation and protein modification in this pathogenic eukaryote. One focus in my laboratory is RNA editing, a novel mechanism for regulating mitochondrial gene expression in which sequence information is added to mRNAs after transcription by specific insertion and deletion of uridine residues. RNA editing is essential for creating translatable open reading frames (ORFs). We are performing functional and biochemical characterization of the large, dynamic RNA-protein complex termed MRB1, which coordinates multiple aspects of the RNA editing process. A second focus is on regulating RNA stability and translational control in T. brucei, which constitute the major methods of gene regulation in this organism. We identified an RNA binding protein, DRBD18, that impacts the stabilities of hundreds of mRNAs. Our data support a model in which posttranslational modification of DRBD18 by arginine methylation acts as a switch to change DRBD18 from an mRNA destabilizer to an mRNA stabilizer by regulating specific protein-protein and protein-RNA interactions. We are testing this model in vitro and in vivo using reporter assays, in vivo protein-RNA cross-linking and protein-protein interaction assays. A third focus is on understanding the mechanisms by which protein arginine methylation modulates trypanosome biology. We performed a global proteomic analysis of the arginine methylome of T. brucei, identifying >1100 methylproteins spanning most cellular compartments and a wide array of functional classes. We are now analyzing novel mechanisms of protein arginine methyltransferase regulation and defining the physiological and molecular functions of arginine methylmarks on selected proteins. I foster a collaborative and flexible laboratory environment, and I encourage my students to explore the research topics that interest them.
Structural Biology; X-ray Crystallography; Bioinformatics; Proteins and metalloenzymes; Protein Function and Structure
Dr. Edward Snell is a Senior Scientist and Cheif Executive officer at the Hauptman-Woodward Medical Research Institute and faculty at the SUNY University at Buffalo Department of Structural Biology. He is a board member on the International Organization for Biological Crystallization, a member of the MacCHESS (The Macromolecular diffraction facility at Cornell High Energy Synchrotron Source) Advisory Committee and a member of the executive committee for the Stanford Synchrotron Radiation Lightsource users organization. He serves as a reviewer for multiple international Journals and both national and international funding agencies. He is on the American Crystallographic Association Communications Committee and chair-elect of the Biological Macromolecules Scientific Interest Group. His research group uses complementary techniques to extract structural and dynamic information from biological macromolecules. This research includes the development of crystallization methodology and the resulting analysis with an emphasis on high-energy light sources. Other techniques in use include Electron Paramagnetic Resonance and spectroscopy. He is experienced in solution scattering techniques, having organized and taught at both national and international meetings. The Snell laboratory research is supported by NIH, NSF, DoD, and NASA in addition to non-federal sources.
DNA Replication, Recombination and Repair; Genome Integrity; Molecular and Cellular Biology; Molecular genetics; Protein Function and Structure
In my laboratory, we are interested in the general problem of maintaining genome stability. To this end, we focus on two distinct aspects of genome stability: 1) the roles of mismatch (MMR) proteins in multiple pathways for DNA repair and 2) the manner in which regulation of dNTP pools, through the regulation of ribonucleotide reductase (RNR) activity, impacts genome integrity. 1) MMR proteins recognize many different types of DNA lesions and then target the lesion for the appropriate repair pathway. We are interested in the mechanism(s) by which recognition of a lesion is translated into the appropriate DNA repair pathway, using the yeast Saccharomyces cerevisiae as a model system. Is it through differential protein-nucleic acid or protein-protein interactions? To address these questions as well as the regulation of DNA repair pathway selection, we use a combination of genetic, biochemical and biophysical approaches. 2) RNR activity modulates the level of dNTPs that are available in a cell at a given time. Higher levels of dNTPs lead to higher mutation rates. We are interested in the various ways in which misregulated dNTP pools might affect cellular metabolism and affect the stability of the genome.
DNA Replication, Recombination and Repair; Gene Expression; Genome Integrity; Microbiology; Molecular and Cellular Biology; Protein Function and Structure; Signal Transduction
We are interested in developing an integrated mechanistic view of how organisms coordinate the actions of their DNA replication machinery with those of other cellular factors involved in DNA repair and damage tolerance. Failure to properly coordinate these functions leads to mutations, genome instability, and in extreme cases, cell death. We utilize a combination of biochemical, biophysical, and genetic approaches to investigate the molecular mechanisms of DNA replication, DNA repair, and error-prone DNA damage tolerance functions in Escherichia coli. The primary mechanism for damage tolerance involves direct bypass of damaged bases in the DNA. This process is inherently error-prone, and is the basis for most mutations. Current efforts are focused on understanding the mechanisms by which the actions of high fidelity and error-prone lesion bypass DNA polymerases are coordinated with each other, as well as other proteins involved in DNA metabolism. Our goal in this work is to develop methods that enable us to control the fidelity of DNA repair for therapeutic gain. We are also interested in understanding the mechanisms that contribute to DNA mutagenesis in the opportunistic human pathogen, P. aeruginosa. P. aeruginosa is a particular problem for individuals afflicted with cystic fibrosis. Persistent colonization of cystic fibrosis airways with P. aeruginosa serves as a major source of morbidity and mortality for these patients. The ability of P. aeruginosa to persist in the airways relies in part on its ability to adapt to the continuously changing environment within the diseased airways. We are particularly interested in determining the contribution of mutagenesis and DNA repair to adaptive mutations that contribute to clonal expansion and pathoadaptation of P. aeruginosa during colonization of cystic fibrosis airways.
Infectious Disease; Microbiology; Microbial Pathogenesis; Molecular and Cellular Biology; Gene Expression; Transcription and Translation; Protein Function and Structure; RNA; Eukaryotic Pathogenesis
In my laboratory, we use molecular biological and biochemical approaches to study Trypanosoma brucei, the causative agent of African sleeping sickness, and Trypanosoma cruzi, which causes Chagas disease in South and Central America. Treatment for these diseases is severely limited due to increasing drug resistance and lack of available drugs. The goal of our work is to discover and exploit critical events that occur in the parasite life cycle that may be used to prevent growth or transmission of the parasite. The major project in my laboratory examines the ribosome, the complex molecular machine that drives protein synthesis. While many features of the ribosome and its assembly pathway are conserved in the parasites we study, we have identified features that are very different from the human host. Our laboratory discovered a pair of trypanosome-specific RNA binding proteins, P34 and P37, that are part of a unique preribosomal complex that is essential for ribosomal biogenesis and survival of trypanosomes. This may suggest that the interaction of these proteins with other components of the ribosomal assembly pathway can be developed as targets for chemotherapy. We are developing a high-throughput screen for small molecules that disrupt the complex in trypanosomes and do not harm the human host. My team and I also collaborate with Dr. Joachim Frank at Columbia University on a project to examine the structure of the ribosome and intermediates in the pathway of assembly using cryo-electron microscopy (cryo-EM). These experiments will provide important information about the unique features of the structure and function of the trypanosome ribosome and further our discovery of potential drug targets. In addition, we continue in a long-standing collaboration with Dr. Beatriz Garat at the Universidad de la Républica in Uruguay, examining both DNA and RNA binding proteins which regulate gene expression in Trypanosoma cruzi. The balance of graduate, undergraduate and medical students and postdoctoral researchers I mentor changes from year to year, though the international quality I strive to maintain has distinguished my laboratory for years: I enjoy having students from around the world as part of my research team. I am the course director for, and lecture in Critical Analysis and Eukaryotic Pathogens. I am also the course director for Eukaryotic Gene Expression and the co-course director for Molecular Parasitology. Additionally, I lecture in Microbiology for Undergraduates.