Protein Function and Structure; Proteins and metalloenzymes; Vitamins and Trace Nutrient
Cytochrome P450 enzymes are powerful 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 our research is to use a combination of biochemical and biophysical tools to investigate structure and function in class I cytochrome P450 enzymes, thereby contributing toward an understanding of how this important class of enzymes work as well as informing the design of therapeutics. This goal is divided between two efforts. First, we are interested in characterizing the substrate and redox partner interactions of the enzyme CYP24A1, the P450 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 our group 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.
Structural Biology; X-ray Crystallography; Microbial Pathogenesis; Microbiology; Protein Function and Structure; Proteins and metalloenzymes
My research program aims to understand how bacteria produce natural products, small molecules that are secreted from the cell to adapt to diverse environments. These molecules allow the bacteria to compete with other microbes or, in the host-pathogen setting, to establish or exacerbate an infection. Natural product biosynthesis may therefore serve as a target for antimicrobial development. My lab uses a variety of techniques to examine these pathways. A core approach is to use X-ray crystallography to determine the molecular structure of proteins that catalyze important steps in natural product biosynthesis. Structural observations are tested and validated using biochemical techniques to examine the catalytic reactions. Finally, molecular and cellular techniques are used to examine biosynthetic gene cluster activity in the cell. These studies will inform efforts to engineer enzymes to produce novel natural product and identify new products of previously uncharacterized pathways. I have a long-standing interest in the Nonribosomal Peptide Synthetases (NRPSs), a family of large, multidomain enzymes that produce important peptide natural products like the antibiotic vancomycin or the anticancer agent bleomycin. NRPSs operate like an assembly line in which the nascent peptide is attached to a carrier domain that shuttles the synthetic intermediates to neighboring catalytic domains. The carrier and catalytic domains are often joined in a single polypeptide that is thousands of residues in length. By examine the crystal structures of large NRPS proteins, we have determined some of the features that enable this fascinating biosynthetic mechanism. Many NRPS products are siderophores, small molecules that bind iron and are required for growth in the pathogenic environment. My lab also studies aerobactin, an NRPS-independent siderophore pathway that is a virulence factor for hypervirulent Klebsiella pneumoniae. We have biochemically and structurally characterized the aerobactin biosynthetic pathway and have developed an approach to find inhibitors of aerobactin biosynthesis that may be tools to probe the pathway chemically to inhibit growth of this human pathogen.
Membrane Transport (Ion Transport); Neurobiology; Protein Function and Structure; Proteins and metalloenzymes; Vitamins and Trace Nutrient
The long term goal of the research conducted in my lab is to learn about the general principles that organisms use to acquire and metabolize the essential nutrients iron, manganese and copper. Since in eukaryotes, iron metabolism, for example, depends on the activity of copper-containing enzymes called ferroxidases, we examine the trafficking copper in cells as well. In addition, as divalent metal ions, manganese and ferrous iron share many of the same trafficking pathways. The first challenge for a cell is to scavenge these metals from the environment. This is true for a yeast cell in culture, for an epithelial cell in your intestine, an endothelial cell in the capillaries in the brain, or a neuron. The second challenge is to efficiently and correctly partition these metals in the cell for subsequent utilization and storage. Ultimately the cell or organism will have to regulate the accumulation of these metals and to ensure that they are not allowed to roam "free" since all three are toxic. Yet all are essential micronutrients, as well. They are required in fundamental cellular processes such as cellular respiration in all organisms, and for vital physiologic functions such as oxygen transport in blood and muscle. The brain has a strong requirement for iron and copper to support the elevated energy metabolism needed to support neuronal function; manganese is essential to neurotransmitter synthesis. This essentiality is contrasted by cytotoxicity that results from their strong tendency to generate oxygen radicals which in turn destroy key cellular components. For example, iron uptake into the brain must be tightly regulated, a process we focus in our research. Failure of this regulation can result in a variety of brain pathologies particularly those that result in degeneration of neuronal function. We study in detail the role of the amyloid precursor protein and alpha-synuclein in iron and manganese trafficking and how these functions are related these proteins‘ roles in neurodegenerative disease.
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.
Cell growth, differentiation and development; DNA Replication, Recombination and Repair; Gene Expression; Molecular and Cellular Biology; Proteins and metalloenzymes; Signal Transduction; Transcription and Translation
The main goal of my research group is to understand the role of N-terminal methylation on human development and disease. I identified the first eukaryotic N-terminal methyltransferases, NRMT1 and NRMT2, and am now working to identify how these enzymes and this new type of methylation affect cancer development and ageing. Our laboratory has shown that NRMT1 functions as a tumor suppressor in mammary glands, and its loss sensitizes breast cancer cells to DNA damaging chemotherapeutics. We have also created the first NRMT1 knockout mouse and shown it to have developmental defects, as well as, exhibit phenotypes of premature ageing. Currently, we are working to understand the exact biochemical pathways that lead from loss of N-terminal methylation to these phenotypes. We are also studying how post-translational modifications on the N-terminus of proteins may interact and dictate protein function, similar to the post-translational modifications found on histone tails.