Catherine Drennan

The Drennan laboratory uses X-ray crystallography as the chief tool for investigating the structure and function of enzymes that are medically important or valuable in environmental remediation. We are particularly interested in metalloprotein biochemistry and in the role of conformational change in catalysis.


The Drennan laboratory seeks to understand how Nature harnesses and re-directs the reactivity of enzyme metallocenters in order to perform challenging reactions. By combining X-ray crystallography with other biophysical methods, our goal is to “visualize” molecular processes by obtaining snapshots of enzymes in action.

Why snapshots? Suppose one wants to understand the process by which a mechanic changes the battery in your car. One photo of a mechanic standing by the car won’t do the trick, but a series of photos of the mechanic changing the battery would be most informative. The same is true when one wants to understand a cellular process; one image of a key enzyme only tells you so much. Thus our laboratory employs multiple biophysical methods to aid in the “visualization” of complex enzyme processes.

Of what do we take snapshots? We want to understand how nature performs the most challenging reactions. Often difficult reactions require the use of organic cofactors or metal ions, which enhance enzyme reactivity. Thus metallo- and cofactor-dependent enzymes are our primary targets. A case in point is the reaction of class I ribonucleotide reductase (RNR), which utilizes a di-iron cofactor to generate protein-based radical species, essential for the reduction of ribonucleotides to deoxyribonucleotides. Although enzymatic reactions like that of RNR are simply spectacular, structural characterization of these enzymes is non-trivial due to issues such as conformational flexibility, protein heterogeneity, structural complexity, and oxygen sensitivity. Our laboratory has specialized in tackling and solving these more challenging structural biology problems. In addition to our focus on radical-based enzymology, we also study metallo- and cofactor-containing enzymes involved in carbon dioxide sequestration and methylation chemistry. Here we seek to obtain snapshots to understand how one-carbon units such as CO2 or CH3 are transferred from enzyme to enzyme, either as part of microbial CO2 fixation pathways or as part of methylation chemistry in humans. In addition, we are interested in how metallocofactors are assembled on their target enzyme and in the regulation of metal uptake by cells.

How do we take snapshots? Although our main technique is X-ray crystallography, we have recently expanded our toolbox and we now combine crystallographic results with data from a variety of other methods, including small angle X-ray scattering (SAXS), electron microscopy (EM), analytical ultracentrifugation (AUC), computational biophysics, absorbance spectroscopy and nuclear magnetic resonance (NMR). Hypotheses generated from our structures can then be tested using both in vitro and in vivo methods.


Jost, M., Born, D.A., Cracan, V.F., Hubbard, P.A., Banerjee, R. and Drennan, C.L. (2015) Structural Basis for Substrate Specificity in Adenosylcobalamin-Dependent Isobutyryl-CoA Mutase and Related Acyl-CoA Mutases, J. Biol. Chem., doi: 10.1074/jbc.M115.676890

Funk, M.A., Marsh, E.N.G., and Drennan, C.L. (2015) Substrate-bound Structures of Benzylsuccinate Synthase Reveal How Toluene is Activated in Anaerobic Hydrocarbon Degradation, J. Biol. Chem., doi: 10.1074/ jbc.M115.670737

Gibson, M.I., Brignole, E.J., Pierce, E., Can, M., Ragsdale, S.W., Drennan, C.L. (2015) Structure of an Oxalate Oxidoreductase Provides Insight into Microbial 2-Oxoacid Metabolism, Biochemistry, 54, 4112-20. PMCID: PMC4498597

Jost, M., Simpson, J.H., and Drennan, C.L. (2015) The Transcription Factor CarH Safeguards Use of Adenosylcobalamin as a Light Sensor by Altering the Photolysis Products, Biochemistry, 54, 3231-4. PMCID: PMC4455981

Jost, M., Cracan, V.F., Hubbard, P.A., Banerjee, R. and Drennan, C.L. (2015) Visualization of a Radical B12 Enzyme with its G-protein Chaperone, Proc. Natl. Acad. Sci. U.S.A., 112, 2419-24. PMCID: PMC4345561

Setser, J.W., Heemstra, J.R. Jr., Walsh, C.T., and Drennan, C.L. (2014) Crystallographic Evidence for Drastic Conformational Changes in the Active Site of a Flavin-dependent N-hydroxylase, Biochemistry, 53, 6063–6077.  PMCID: PMC4179590

Wei, Y.*, Funk, M.A., Rosado, L.A., Baek, J., Drennan, C.L.*, and Stubbe, J.* (2014) The Class III Ribonucleotide Reductase from Neisseria bacilliformis Can Utilize Thioredoxin as a Reductant, Proc. Natl. Acad. Sci. U.S.A. 111, E3756-E3765.  PMCID: PMC4246965 *Corresponding Authors

Funk, M.A., Judd, E.T., Marsh, E.N.G., Elliott, S.J., and Drennan, C.L. (2014) Structures of Benzylsuccinate Synthase Elucidate Roles of Accessory Subunits in Glycyl Radical Enzyme Activation and Activity, Proc. Natl. Acad. Sci. U.S.A. 111, 10161-10166. PMCID: PMC4104874

Dowling, D.P., Bruender, N.A., Young, A.P., McCarty, R.M., Bandarian, V., Drennan, C.L. (2014) Radical SAM Enzyme QueE Defines a New Minimal Core Fold and Metal-dependent Mechanism, Nat. Chem. Biol. 10, 106-112.  PMCID: PMC3939041

Goldman, P.J., Grove, T.L., Booker, S.J., Drennan, C.L. (2013) X-ray Analysis of Butirosin Biosynthetic Enzyme BtrN Redefines Structural Motifs for AdoMet Radical Chemistry, Proc. Natl. Acad. Sci. U.S.A. 110, 15949-15954. PMCID: PMC3791736

Goldman, P.J., Grove, T.L., Sites, L.A., McLaughlin, M.I., Booker, S.J., Drennan, C.L. (2013) X-ray Structure of an AdoMet Radical Activase Reveals an Anaerobic Solution for Formylglycine Posttranslational Modification, Proc. Natl. Acad. Sci. U.S.A. 110, 8519-8524. PMCID: PMC3666706

Chang, W-C., Dey, M., Liu, P., Mansoorabadi, S.O., Moon, S-J,  Z.K., Drennan, C.L., and Liu, H-W. (2013) Mechanistic Studies of an Unprecedented Enzyme-catalyzed 1,2-Phosphono Migration Reaction, Nature 496, 114-118.  PMCID: PMC3725809

Minnihan, E.C., Ando, N., Brignole, E.J., Olshansky, L., Chittuluru, J., Asturias*, F.J., Drennan*, C.L., Nocera*, D.G., and Stubbe*, J. (2013) Generation of a Stable, Aminotyrosyl Radical-induced α2β2 Complex of Escherichia coli Class Ia Ribonucleotide Reductase, Proc. Natl. Acad. Sci. U.S.A. 110, 3835-1340. PMCID: PMC3593893     *Corresponding authors.

Ando, N., Kung, Y., Can, M., Bender G., Ragsdale, S.W., and Drennan, C.L. (2012) Transient B12-dependent Methyltransferase Complexes Revealed by Small-angle X-ray Scattering, J. Am. Chem. Soc. 134, 17945-17954. PMCID: PMC3484714

Goldman, P.J., Ryan, K.S,  Hamill, M.J., Howard-Jones, A.R., Walsh, C.T., Elliott, S.J., and Drennan, C.L. (2012) An Unusual Role for a Mobile Flavin in StaC-like Indolocarbazole Biosynthetic Enzymes, Chem. Biol 19, 855-865.  PMCID: PMC3437190

Zimanyi, C.M., Ando, N., Brignole, E. J., Asturias, F.J., Stubbe, J., and Drennan, C.L. (2012) Tangled up in Knots — Structures of Inactivated Forms of E. coli class Ia Ribonucleotide Reductase, Structure 20, 1374-1383.  PMCID: PMC3459064

Kung, Y., Ando, N., Doukov, T.I., Blasiak, L.C., Bender, G., Seravalli, J., Ragsdale, S.W., and Drennan, C.L. (2012) Visualising Molecular Juggling within a B12-dependent Methyltransferase Complex, Nature 484, 265-269.  PMCID: PMC332619

Ando, N., Brignole, E. J., Zimanyi, C.M., Funk, M.A., Yokoyama. K., Asturias, F.J., Stubbe, J., and Drennan, C.L. (2011) Structural Interconversions Modulate Activity of E. coli Ribonucleotide Reductase, Proc. Natl. Acad. Sci. U.S.A. 108, 21046-21051PMCID: PMC3248520

Yun, D., Dey, M., Higgins, L.J., Yan, F., Liu, H.W., and Drennan, C.L. (2011) Structural Basis of Regiospecificity of a Mononuclear Iron Enzyme in Antibiotic Fosfomycin Biosynthesis, J. Am. Chem. Soc. 133, 11262–11269.  PMCID: PMC3140168

Phillips, C.M., Schreiter, E.R., Stultz, C.M. and Drennan, C.L (2010) Structural Basis of Low Affinity Nickel Binding to the Nickel-Responsive Transcription Factor NikR from Escherichia coli, Biochemistry 49, 7830–7838. PMCID: PMC2934763

Kung, Y., Doukov, T.I., Seravalli, J., Ragsdale, S.W., Drennan, C.L. (2009) Crystallographic Snapshots of Cyanide- and Water-Bound C-Clusters from Bifunctional Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase, Biochemistry 48, 7432-7440.  PMCID: PMC2721637

Vey, J. L., Yang, J., Li M., Broderick, W. E., Broderick, J. B., Drennan, C. L. (2008) Structural Basis for Glycyl Radical Formation by Pyruvate Formate-lyase Activating Enzyme, Proc. Natl. Acad. Sci. U.S.A. 105, 16137-16141. PMCID: PMC2571006

Schreiter, E.R., Wang, S. C., Zamble, D.B., and Drennan, C.L. (2006) NikR-operator Complex Structure and the Mechanism of Repressor Activation by Metal Ions, Proc. Natl. Acad. Sci. U.S.A.

Blasiak, L.C., Vaillancourt, F.H., Walsh, C.T., and Drennan, C.L. (2006) Crystal Structure of the Non-haem Iron Halogenase SyrB2 in Syringomycin Biosynthesis, Nature 440, 368-371.