@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{han_hawkins_adams_kelly_2012, title={Epimerase (Msed_0639) and Mutase (Msed_0638 and Msed_2055) Convert (S)-Methylmalonyl-Coenzyme A (CoA) to Succinyl-CoA in the Metallosphaera sedula 3-Hydroxypropionate/4-Hydroxybutyrate Cycle}, volume={78}, ISSN={["1098-5336"]}, DOI={10.1128/aem.01312-12}, abstractNote={ABSTRACT Crenarchaeotal genomes encode the 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB) cycle for carbon dioxide fixation. Of the 13 enzymes putatively comprising the cycle, several of them, including methylmalonyl-coenzyme A (CoA) epimerase (MCE) and methylmalonyl-CoA mutase (MCM), which convert ( S )-methylmalonyl-CoA to succinyl-CoA, have not been confirmed and characterized biochemically. In the genome of Metallosphaera sedula (optimal temperature [ T opt ], 73°C), the gene encoding MCE (Msed_0639) is adjacent to that encoding the catalytic subunit of MCM-α (Msed_0638), while the gene for the coenzyme B 12 -binding subunit of MCM (MCM-β) is located remotely (Msed_2055). The expression of all three genes was significantly upregulated under autotrophic compared to heterotrophic growth conditions, implying a role in CO 2 fixation. Recombinant forms of MCE and MCM were produced in Escherichia coli ; soluble, active MCM was produced only if MCM-α and MCM-β were coexpressed. MCE is a homodimer and MCM is a heterotetramer (α 2 β 2 ) with specific activities of 218 and 2.2 μmol/min/mg, respectively, at 75°C. The heterotetrameric MCM differs from the homo- or heterodimeric orthologs in other organisms. MCE was activated by divalent cations (Ni 2+ , Co 2+ , and Mg 2+ ), and the predicted metal binding/active sites were identified through sequence alignments with less-thermophilic MCEs. The conserved coenzyme B 12 -binding motif ( DXHXXG -SXL-GG) was identified in M. sedula MCM-β. The two enzymes together catalyzed the two-step conversion of ( S )-methylmalonyl-CoA to succinyl-CoA, consistent with their proposed role in the 3-HP/4-HB cycle. Based on the highly conserved occurrence of single copies of MCE and MCM in Sulfolobaceae genomes, the M. sedula enzymes are likely to be representatives of these enzymes in the 3-HP/4-HB cycle in crenarchaeal thermoacidophiles. }, number={17}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Han, Yejun and Hawkins, Aaron S. and Adams, Michael W. W. and Kelly, Robert M.}, year={2012}, month={Sep}, pages={6194–6202} } @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} } @article{hawkins_han_lian_loder_menon_iwuchukwu_keller_leuko_adams_kelly_2011, title={Extremely Thermophilic Routes to Microbial Electrofuels}, volume={1}, ISSN={["2155-5435"]}, DOI={10.1021/cs2003017}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVViewpointNEXTExtremely Thermophilic Routes to Microbial ElectrofuelsAaron S. Hawkins†, Yejun Han†, Hong Lian†, Andrew J. Loder†, Angeli L. Menon‡, Ifeyinwa J. Iwuchukwu‡, Matthew Keller‡, Therese T. Leuko‡, Michael W.W. Adams‡, and Robert M. Kelly*†View Author Information† Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, United States‡ Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, United StatesPhone: (919) 515-6396. Fax: (919) 515-3465. E-mail: [email protected]Cite this: ACS Catal. 2011, 1, 9, 1043–1050Publication Date (Web):August 1, 2011Publication History Received7 June 2011Published online8 August 2011Published inissue 2 September 2011https://pubs.acs.org/doi/10.1021/cs2003017https://doi.org/10.1021/cs2003017editorialACS PublicationsCopyright © 2011 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views2851Altmetric-Citations36LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (3 MB) Get e-AlertscloseSUBJECTS:Bacteria,Genetics,Hydrogen,Oxides,Peptides and proteins Get e-Alerts}, number={9}, journal={ACS CATALYSIS}, author={Hawkins, Aaron S. and Han, Yejun and Lian, Hong and Loder, Andrew J. and Menon, Angeli L. and Iwuchukwu, Ifeyinwa J. and Keller, Matthew and Leuko, Therese T. and Adams, Michael W. W. and Kelly, Robert M.}, year={2011}, month={Sep}, pages={1043–1050} }