@article{lian_zeldes_lipscomb_hawkins_han_loder_nishiyama_adams_kelly_2016, title={Ancillary contributions of heterologous biotin protein ligase and carbonic anhydrase for CO2 incorporation into 3-hydroxypropionate by metabolically engineered Pyrococcus furiosus}, volume={113}, number={12}, journal={Biotechnology and Bioengineering}, author={Lian, H. and Zeldes, B. M. and Lipscomb, G. L. and Hawkins, A. B. and Han, Y. J. and Loder, A. J. and Nishiyama, D. and Adams, M. W. W. and Kelly, R. M.}, year={2016}, pages={2652–2660} }
 @article{loder_han_hawkins_lian_lipscomb_schut_keller_adams_kelly_2016, title={Reaction kinetic analysis of the 3-hydroxypropionate/4-hydroxybutyrate CO2 fixation cycle in extremely thermoacidophilic archaea}, volume={38}, ISSN={["1096-7184"]}, DOI={10.1016/j.ymben.2016.10.009}, abstractNote={The 3-hydroxypropionate/4-hydroxybutyrate (3HP/4HB) cycle fixes CO2 in extremely thermoacidophilic archaea and holds promise for metabolic engineering because of its thermostability and potentially rapid pathway kinetics. A reaction kinetics model was developed to examine the biological and biotechnological attributes of the 3HP/4HB cycle as it operates in Metallosphaera sedula, based on previous information as well as on kinetic parameters determined here for recombinant versions of five of the cycle enzymes (malonyl-CoA/succinyl-CoA reductase, 3-hydroxypropionyl-CoA synthetase, 3-hydroxypropionyl-CoA dehydratase, acryloyl-CoA reductase, and succinic semialdehyde reductase). The model correctly predicted previously observed features of the cycle: the 35–65% split of carbon flux through the acetyl-CoA and succinate branches, the high abundance and relative ratio of acetyl-CoA/propionyl-CoA carboxylase (ACC) and MCR, and the significance of ACC and hydroxybutyryl-CoA synthetase (HBCS) as regulated control points for the cycle. The model was then used to assess metabolic engineering strategies for incorporating CO2 into chemical intermediates and products of biotechnological importance: acetyl-CoA, succinate, and 3-hydroxypropionate.}, journal={METABOLIC ENGINEERING}, author={Loder, Andrew J. and Han, Yejun and Hawkins, Aaron B. and Lian, Hong and Lipscomb, Gina L. and Schut, Gerrit J. and Keller, Matthew W. and Adams, Michael W. W. and Kelly, Robert M.}, year={2016}, month={Nov}, pages={446–463} }
 @article{hawkins_lian_zeldes_loder_lipscomb_schut_keller_adams_kelly_2015, title={Bioprocessing analysis of Pyrococcus furiosus strains engineered for CO2-based 3-hydroxypropionate production}, volume={112}, ISSN={["1097-0290"]}, DOI={10.1002/bit.25584}, abstractNote={ABSTRACT}, number={8}, journal={BIOTECHNOLOGY AND BIOENGINEERING}, author={Hawkins, Aaron B. and Lian, Hong and Zeldes, Benjamin M. and Loder, Andrew J. and Lipscomb, Gina L. and Schut, Gerrit J. and Keller, Matthew W. and Adams, Michael W. W. and Kelly, Robert M.}, year={2015}, month={Aug}, pages={1533–1543} }
 @article{hawkins_adams_kelly_2014, title={Conversion of 4-Hydroxybutyrate to Acetyl Coenzyme A and Its Anapleurosis in the Metallosphaera sedula 3-Hydroxypropionate/4-Hydroxybutyrate Carbon Fixation Pathway}, volume={80}, ISSN={["1098-5336"]}, DOI={10.1128/aem.04146-13}, abstractNote={ABSTRACT}, number={8}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Hawkins, Aaron B. and Adams, Michael W. W. and Kelly, Robert M.}, year={2014}, month={Apr}, pages={2536–2545} }
 @misc{hawkins_mcternan_lian_kelly_adams_2013, title={Biological conversion of carbon dioxide and hydrogen into liquid fuels and industrial chemicals}, volume={24}, ISSN={["1879-0429"]}, DOI={10.1016/j.copbio.2013.02.017}, abstractNote={Non-photosynthetic routes for biological fixation of carbon dioxide into valuable industrial chemical precursors and fuels are moving from concept to reality. The development of 'electrofuel'-producing microorganisms leverages techniques in synthetic biology, genetic and metabolic engineering, as well as systems-level multi-omic analysis, directed evolution, and in silico modeling. Electrofuel processes are being developed for a range of microorganisms and energy sources (e.g. hydrogen, formate, electricity) to produce a variety of target molecules (e.g. alcohols, terpenes, alkenes). This review examines the current landscape of electrofuel projects with a focus on hydrogen-utilizing organisms covering the biochemistry of hydrogenases and carbonic anhydrases, kinetic and energetic analyses of the known carbon fixation pathways, and the state of genetic systems for current and prospective electrofuel-producing microorganisms.}, number={3}, journal={CURRENT OPINION IN BIOTECHNOLOGY}, author={Hawkins, Aaron S. and McTernan, Patrick M. and Lian, Hong and Kelly, Robert M. and Adams, Michael W. W.}, year={2013}, month={Jun}, pages={376–384} }
 @article{keller_schut_lipscomb_menon_iwuchukwu_leuko_thorgersen_nixon_hawkins_kelly_et al._2013, title={Exploiting microbial hyperthermophilicity to produce an industrial chemical, using hydrogen and carbon dioxide}, volume={110}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.1222607110}, abstractNote={
            Microorganisms can be engineered to produce useful products, including chemicals and fuels from sugars derived from renewable feedstocks, such as plant biomass. An alternative method is to use low potential reducing power from nonbiomass sources, such as hydrogen gas or electricity, to reduce carbon dioxide directly into products. This approach circumvents the overall low efficiency of photosynthesis and the production of sugar intermediates. Although significant advances have been made in manipulating microorganisms to produce useful products from organic substrates, engineering them to use carbon dioxide and hydrogen gas has not been reported. Herein, we describe a unique temperature-dependent approach that confers on a microorganism (the archaeon
            Pyrococcus furiosus,
            which grows optimally on carbohydrates at 100°C) the capacity to use carbon dioxide, a reaction that it does not accomplish naturally. This was achieved by the heterologous expression of five genes of the carbon fixation cycle of the archaeon
            Metallosphaera sedula,
            which grows autotrophically at 73°C. The engineered
            P. furiosus
            strain is able to use hydrogen gas and incorporate carbon dioxide into 3-hydroxypropionic acid, one of the top 12 industrial chemical building blocks. The reaction can be accomplished by cell-free extracts and by whole cells of the recombinant
            P. furiosus
            strain. Moreover, it is carried out some 30°C below the optimal growth temperature of the organism in conditions that support only minimal growth but maintain sufficient metabolic activity to sustain the production of 3-hydroxypropionate. The approach described here can be expanded to produce important organic chemicals, all through biological activation of carbon dioxide.
          }, number={15}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Keller, Matthew W. and Schut, Gerrit J. and Lipscomb, Gina L. and Menon, Angeli L. and Iwuchukwu, Ifeyinwa J. and Leuko, Therese T. and Thorgersen, Michael P. and Nixon, William J. and Hawkins, Aaron S. and Kelly, Robert M. and et al.}, year={2013}, month={Apr}, pages={5840–5845} }
 @article{hawkins_han_bennett_adams_kelly_2013, title={Role of 4-Hydroxybutyrate-CoA Synthetase in the CO2 Fixation Cycle in Thermoacidophilic Archaea}, volume={288}, ISSN={["1083-351X"]}, DOI={10.1074/jbc.m112.413195}, abstractNote={Background: Thermoacidophilic Sulfolobales contain a novel CO2 fixation pathway; all enzymes but one have been accounted for in Metallosphaera sedula. Results: Enzymes encoded in Msed_0394 and Msed_0406 each exhibit 4-hydroxybutyrate-CoA synthetase activity, consistent with transcriptomic evidence. Conclusion: Msed_0406 is likely the physiologically relevant enzyme in the cycle. Significance: All enzymes are now accounted for in the CO2 fixation cycle of M. sedula. Metallosphaera sedula is an extremely thermoacidophilic archaeon that grows heterotrophically on peptides and chemolithoautotrophically on hydrogen, sulfur, or reduced metals as energy sources. During autotrophic growth, carbon dioxide is incorporated into cellular carbon via the 3-hydroxypropionate/4-hydroxybutyrate cycle (3HP/4HB). To date, all of the steps in the pathway have been connected to enzymes encoded in specific genes, except for the one responsible for ligation of coenzyme A (CoA) to 4HB. Although several candidates for this step have been identified through bioinformatic analysis of the M. sedula genome, none have been shown to catalyze this biotransformation. In this report, transcriptomic analysis of cells grown under strict H2-CO2 autotrophy was consistent with the involvement of Msed_0406 and Msed_0394. Recombinant versions of these enzymes catalyzed the ligation of CoA to 4HB, with similar affinities for 4HB (Km values of 1.9 and 1.5 mm for Msed_0406 and Msed_0394, respectively) but with different rates (1.69 and 0.22 μmol × min−1 × mg−1 for Msed_0406 and Msed_0394, respectively). Neither Msed_0406 nor Msed_0394 have close homologs in other Sulfolobales, although low sequence similarity is not unusual for acyl-adenylate-forming enzymes. The capacity of these two enzymes to use 4HB as a substrate may have arisen from simple modifications to acyl-adenylate-forming enzymes. For example, a single amino acid substitution (W424G) in the active site of the acetate/propionate synthetase (Msed_1353), an enzyme that is highly conserved among the Sulfolobales, changed its substrate specificity to include 4HB. The identification of the 4-HB CoA synthetase now completes the set of enzymes comprising the 3HP/4HB cycle.}, number={6}, journal={JOURNAL OF BIOLOGICAL CHEMISTRY}, author={Hawkins, Aaron S. and Han, Yejun and Bennett, Robert K. and Adams, Michael W. W. and Kelly, Robert M.}, year={2013}, month={Feb}, pages={4012–4022} }