The flexible N-terminus of BchL protects its [4Fe-4S] cluster in oxygenic environments and autoinhibits activity
Lance C. Seefeldt. The dark-operative protochlorophyllide oxidoreductase (DPOR) enzyme contains two [4Fe-4S]- containing component proteins (BchL and BchNB) that assemble in an ATP-dependent fashion to coordinate electron transfer and reduction of proto
An Efficient Viologen-Based Electron Donor to Nitrogenase
Lance C. Seefeldt, T. Leo Liu, Artavazd Badalyan, Zhi-Yong Yang, Bo Hu, Jian Luo, Maowei Hu. Nitrogenase catalyzes the reduction of N2 to NH3, supporting all biological nitrogen fixation. Electron donors to this enzyme are ferredoxin or flavodoxin (in v
Rapid and direct measurement of methyltransferase activity in about 30 min
Joan M. Hevel. Owen M. Price. Protein arginine methylation is a widespread eukaryotic posttranslational modification that occurs to both histone and non-histone proteins. The S-adenosyl-L-methionine (AdoMet or SAM)-dependent modification is catalyzed by t...
Establishing a Thermodynamic Landscape for the Active Site of Mo-Dependent Nitrogenase
Lance C. Seefeldt, Zhi-Yong Yang. Nitrogenase enzymes are the only biological catalysts able to convert N2 to NH3. Molybdenum-dependent nitrogenase consists of two proteins and three metallocofactors that sequentially shuttle eight electrons between thr
Time-Resolved EPR Study of H2 Reductive Elimination from the Photoexcited Nitrogenase Janus E4(4H) Intermediate
Lance C. Seefeldt. Nitrogenase is activated for N2 reduction through the accumulation of four reducing equivalents at the active-site FeMo-cofactor (FeMo-co: Fe7S9MoC; homocitrate) to form the key Janus intermediate, denoted E4(4H), whose lowest-energy
Spectroscopic Description of the E1 State of Mo Nitrogenase Based on Mo and Fe X-ray Absorption and Mossbauer Studies
Lance C. Seefeldt, Zhi-Yong Yang. Mo nitrogenase (N2ase) utilizes a two-component protein system, the catalytic MoFe and its electron-transfer partner FeP, to reduce atmospheric dinitrogen (N2) to ammonia (NH3). The FeMo cofactor contained in the MoFe p
Phototrophic N2 and CO2 Fixation Using a Rhodopseudomonas palustris-H2 Mediated Electrochemical System With Infrared Photons
Scott A. Ensign, Lance C. Seefeldt, Mathangi Soundararajan A promising approach for the synthesis of high value reduced compounds is to couple bacteria to the cathode of an electrochemical cell, with delivery of electrons from the electrode driving red
Electrocatalytic N2 Reduction to NH3 Using Enzyme Nitrogenase
Lance C. Seefeldt, Artavazd Badalyan, Zhi-Yong Yang. The reduction of dinitrogen (N2) to ammonia (NH3) is an important reaction that supports all of life and many industrial processes. An enzyme found in bacteria called nitrogenase catalyzes this reacti
Modified substrate specificity of a methyltransferase domain by protein insertion into an adenylation domain of the bassianolide synthetase
Joan M. Hevel Background: Creating designer molecules using a combination of select domains from polyketide synthases and/ or nonribosomal peptide synthetases (NRPS) continues to be a synthetic goal. However, an incomplete understanding of how protein-pro...
Mo-, V-, and Fe-Nitrogenases Use a Universal Eight-Electron Reductive-Elimination Mechanism To Achieve N2 Reduction
Lance C. Seefeldt, Derek F. Harris, Hayden Kallas, Zhi-Yong Yang. Three genetically distinct, but structurally similar, isozymes of nitrogenase catalyze biological N2 reduction to 2NH3: Mo-, V-, and Fe-nitrogenase, named respectively for the metal (M) i
Structural basis of Type IV CRISPR RNA biogenesis by a Cas6 encoribonuclease
Ryan N. Jackson, Hannah N. Taylor, Valerie M. Crowley, Keith J. Olsen Prokaryotic CRISPR-Cas adaptive immune systems rely on small non-coding RNAs derived from CRISPR loci to recognize and destroy complementary nucleic acids. However, the mechanism of T
High-Resolution ENDOR Spectroscopy Combined with Quantum Chemical Calculations Reveals the Structure of Nitrogenase Janus
Lance C. Seefeldt. We have shown that the key state in N2 reduction to two NH3 molecules by the enzyme nitrogenase is E4(4H), the “Janus” intermediate, which has accumulated four [e−/H+] and is poised to undergo reductive elimination of H2 coupled to N2
Interfacial amino acide support Spa47 oligomerization and shigella type three secretion system activation
Nicholas E. Dickenson, Sean J. Johnson, Hannah J. Demler, Heather B. Case, Yalemi Morales, Abram R. Bernard. Like many Gram-negative pathogens, Shigella rely on a type three secretion system (T3SS) for injection of effector proteins directly into euka
Examining Product Specificity in Protein Arginine Methyltransferase 7 (PRMT7) Using Quantum and Molecular Mechanical Simulations
Joan M. Hevel Protein arginine methyltransferase 7 (PRMT7) catalyzes the formation of monomethylarginine (MMA) but is incapable of performing a dimethylation. Given that PRMT7 performs vital functions in mammalian cells and has been implicated in a variet...
Electrochemical Dinitrogen Reduction to Ammonia by Mo2N: Catalysis or Decomposition?
Lance C. Seefeldt, T. Leo Liu, Maowei Hu, Bo Hu. Instead of catalyzing electrochemical reduction of N2, we found that tetragonal Mo2N undergoes decomposition and results in the generation of ammonia. The present results call urgent attention to the need
The NifZ accessory protein has an equivalent function in maturation of both nitrogenase MoFe protein P-clusters
Lance C. Seefeldt, Zhi-Yong Yang. The Mo-dependent nitrogenase comprises two interacting components called the Fe protein and the MoFe protein. The MoFe protein is an a2b2 heterotetramer that harbors two types of complex metalloclusters, both of which a
Transition State Analysis of the Reaction Catalyzed by the Phosphotriesterase from Sphingobium sp. TCM1
Alvan C. Hengge Organophosphorus flame retardants are stable toxic compounds used in nearly all durable plastic products and are considered major emerging pollutants. The phosphotriesterase from Sphingobium sp. TCM1 (Sb-PTE) is one of the few enzymes know...
Transition-State Interactions in a Promiscuous Enzyme: Sulfate and Phosphate Monoester Hydrolysis by Pseudomonas aeruginosa Arylsulfatase
Alvan C. Hengge Pseudomonas aeruginosa arylsulfatase (PAS) hydrolyzes sulfate and, promiscuously, phosphate monoesters. Enzyme-catalyzed sulfate transfer is crucial to a wide variety of biological processes, but detailed studies of the mechanistic contrib...
Catalytic mechanism for the conversion of salicylate into catechol by the flavin-dependent monooxygenase salicylate hydroxylase
Alvan C. Hengge Salicylate hydroxylase (NahG) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of salicylate into catechol in the naphthalene degradation pathway in Pseudomonas putida G7.We explored the mechanism of act...
The ammonium transporter AmtB and the PII signal transduction protein GlnZ are required to inhibit DraG in Azospirillum brasilense
Lance C. Seefeldt. The ammonium-dependent posttranslational regulation of nitrogenase activity in Azospirillum brasilense requires dinitrogenase reductase ADPribosyl transferase (DraT) and dinitrogenase reductase ADP-glycohydrolase (DraG). These enzymes
A Voltammetric Study of Nitrogenase Catalysis Using Electron Transfer Mediators
Lance C. Seefeldt, Artavazd Badalyan, Zhi-Yong Yang. Nitrogenase catalyzes the reduction of an array of small molecules, including N2 to NH3, by delivering electrons and protons to substrates bound to the active site metal cluster FeMocofactor. A chall
Methods in ENZYMOLOGY: Application of affinity purification methods for analysis of the nitrogenase system from Azotobacter vinelandii
Lance C. Seefeldt, Zhi-Yong Yang. Pg. 231-251. Nitrogenases are complex two-component metalloenzymes that catalyze biological nitrogen fixation. Three different nitrogenase types are found in the model nitrogen-fixing microbe azotabacter vinelandii. In
Shutting down shigella secretions: characterizing small molecule type three secretion system ATPase inhibitors
Heather B. Case, Dominic S. Mattock and Nicholas E. Dickenson Many important human pathogens rely on one or more type three secretion systems (T3SSs) to inject bacterial effector proteins directly into the host cell cytoplasm. Secretion of protein through...
Kinetic characterization of the shigella type three secretions system ATPase spa47 using ATP
Heather B. Case and Nicholas E. Dickenson
Control of electron transfer in nitrogenase
Lance C. Seefeldt. The bacterial enzyme nitrogenase achieves the reduction of dinitrogen (N2) to ammonia (NH3) utilizing electrons, protons, and energy from the hydrolysis of ATP. Building on earlier foundational knowledge, recent studies provide molec
A yoph ptp1b chimera shows the importance of the wpd-loop sequence to the activity, structure, and dynamics of protein tyrosine phosphatases
Gwendolyn Moise, Yalemi Morales, Victor Beaumont, Timothy Caradonna, J. Patrick Loria, Sean J. Johnson, and Alvan C. Hengge ABSTRACT: To study factors that affect WPD-loop motion in protein tyrosine phosphatases (PTPs), a chimera of PTP1B and YopH was cre...
A new era for electron bifurcation
Lance C. Seefeldt. Electron bifurcation, or the coupling of exergonic and endergonic oxidation-reduction reactions, was discovered by Peter Mitchell and provides an elegant mechanism to rationali
Structure of frequency-interacting RNA helicase from neurospora crassa reveals high flexibility in a domain critical for circadian rhythm and RNA surveiillance
Morales Y., Olsen KJ, Bulcher JM, Johnson SJ ABSTRACT:The FRH (frequency-interacting RNA helicase) protein is the Neurospora crassa homolog of yeast Mtr4, an essential RNA helicase that plays a central role in RNA metabolism as an activator of the nucle
Electrocatalytic CO2 reduction catalyzed by nitrogenase MoFe and FeFe proteins
Bo Hu, Derek F. Harris, Dennis R. Dean, T. Leo Liu, Zhi-Yong Yang, Lance C. Seefeldt: Nitrogenases catalyze biological dinitrogen (N2) reduction to ammonia (NH3), and also reduce a number of non-physiological substrates, including carbon dioxide (CO2) to ...
MxiN differentially regulates monomeric and oligomeric species of the Shigella type three secretion system ATPase Spa47
Heather B. Case and Nicholas E. Dickenson: Shigella rely entirely on the action of a single type three secretion system (T3SS) to support cellular invasion of colonic epithelial cells and to circumvent host immune responses. The ATPase Spa47 resides at th...
Mechanism of N2 reduction catalyzed by Fe-nitrogenase involves reductive elimination of H2
Derek F. Harris, Dmitriy A. Lukoyanov, Sudipta Shaw, Phil Compton, Monika Tokmina-Lukaszewska, Brian Bothner, Neil Kelleher, Dennis R. Dean, Brian M. Hoffman, and Lance C. Seefeldt: Of the three forms of nitrogenase (Mo-nitrogenase, V-nitrogenase, and Fe-...
Phe71 in type III trypanosoomal protein rrginine methyltransferase 7 (TbPRMT7) restricts to monomethylation
Tamar B. Caceres, Abhishek Thakur, Owen M Price, Nicole Ippolito, Jun Li, Jun Qu, Orlando Acevedo and Joan Hevel ABSTRACT: Protein arginine methyltransferase 7 (PRMT7) is unique within the PRMT family as it is the only isoform known to exclusively make m...
Conformational dynamics of DNA binding and Cas3 recruitment by the CRISPR RNA-guided cascade complex
Paul B. G. van Erp, Angela Patterson, Ravi Kant, Luke Berry, Sarah M. Golden, Brittney L. Forsman, Joshua Carter, Ryan N. Jackson, Brian Bothner, and Blake Wiedenheft: Bacteria and archaea rely on CRISPR (clustered regularly interspaced short palindromic ...
Conformational regulation of CRISPR-associated nucleases
Jackson, R., van Erp, P.B, Sternberg, S.H, Wiedenheft, B.: Adaptive immune systems in bacteria and archaea rely on small CRISPR-derived RNAs (crRNAs) to guide specialized nucleases to foreign nucleic acids. The activation of these nucleases is controlled ...
Thermal and elastic characterization of glassy carbon thin films by photoacoustic measurements
D.D. Markushev, J. Ordonez-Miranda, M.D. Rabasovi´c, M. Chirtoc, D.M. Todorovi´c, S.E. Bialkowski, D. Korte, and M. Franko: A portable photoacoustic device is designed and applied to measure thermal diffusivity and linear thermal expansion coefficient of ...
Faculty member in the College of Science, Department of Chemistry and Biochemistry