The Bioinorganic and Biological Chemistry of Microbial Life on CO and CO2
Department of Biochemistry and Redox Biology Center Seminar Series
4:00 pm –
5:00 pm
Target Audiences:
Contact:
Samantha DeGrave Madderom, (402) 472-7087, sdegrave-madderom2@unl.edu
Dr. Stephen W. Ragsdale, Biological Chemistry University of Michigan
There are six known CO2 fixation pathways and among these, the Wood-Ljungdahl (or reductive acetyl-CoA) Pathway (WLP) (summarized in Fig. below) is the only one that both generates and utilizes carbon monoxide as an intermediate. It is the only one that conserves energy; in contrast, the Calvin cycle requires three ATP for each entering CO2. Found in strictly anaerobic microbes, this pathway allows microbes to grow on carbon monoxide, H2 and CO2 as their sole energy and carbon sources and is important to the evolution of life, as it was present in the last universal common ancestor.
At the heart of the WLP is CO dehydrogenase/acetyl-CoA synthase (CODH/ACS). Rich in Ni and FeS clusters, CODH catalyzes CO2 reduction to CO, which then travels through an interprotein tunnel to the ACS active site. Then, the CO is fixed into acetyl-CoA via a series of nickel-based organometallic intermediates (Ni-CH3, Ni-CO, Ni-acetyl), which have been recently elucidated. We have recently captured the structure of each of these organometallic intermediates, elucidated a CO gas tunnel within the CODH/ACS enzyme complex, described large conformational changes in several of the enzymes and complexes, and discovered a molecular alcove required for autotrophic growth of microbes by the WLP.
References:
1. Cohen, S.E., et al. (2020) Crystallographic characterization of the carbonylated A-cluster in carbon monoxide dehydrogenase/acetyl-CoA synthase, ACS Catalysis, 10: 9741-9746.
2. James, C.D., et al. (2020) 13C electron nuclear double resonance spectroscopy shows acetyl-CoA synthase binds two substrate CO in multiple binding modes and reveals the importance of a CO-binding ‘alcove’, J. Am. Chem. Soc., 142, 15362-15370.
3. Can M, et al. (2023) Characterization of Methyl- and Acetyl-Ni Intermediates in Acetyl CoA Synthase Formed during Anaerobic CO2 and CO Fixation. J. Am. Chem. Soc.. 145:13696-708.
4. Wiley, S., Griffith, C., Eckert, P., Mueller, A. P., Nogle, R., Simpson, S. D. et al. (2024) An alcove at the acetyl-CoA synthase nickel active site is required for productive substrate CO binding and anaerobic carbon fixation Journal of Biological Chemistry 300, 107503
There are six known CO2 fixation pathways and among these, the Wood-Ljungdahl (or reductive acetyl-CoA) Pathway (WLP) (summarized in Fig. below) is the only one that both generates and utilizes carbon monoxide as an intermediate. It is the only one that conserves energy; in contrast, the Calvin cycle requires three ATP for each entering CO2. Found in strictly anaerobic microbes, this pathway allows microbes to grow on carbon monoxide, H2 and CO2 as their sole energy and carbon sources and is important to the evolution of life, as it was present in the last universal common ancestor.
At the heart of the WLP is CO dehydrogenase/acetyl-CoA synthase (CODH/ACS). Rich in Ni and FeS clusters, CODH catalyzes CO2 reduction to CO, which then travels through an interprotein tunnel to the ACS active site. Then, the CO is fixed into acetyl-CoA via a series of nickel-based organometallic intermediates (Ni-CH3, Ni-CO, Ni-acetyl), which have been recently elucidated. We have recently captured the structure of each of these organometallic intermediates, elucidated a CO gas tunnel within the CODH/ACS enzyme complex, described large conformational changes in several of the enzymes and complexes, and discovered a molecular alcove required for autotrophic growth of microbes by the WLP.
References:
1. Cohen, S.E., et al. (2020) Crystallographic characterization of the carbonylated A-cluster in carbon monoxide dehydrogenase/acetyl-CoA synthase, ACS Catalysis, 10: 9741-9746.
2. James, C.D., et al. (2020) 13C electron nuclear double resonance spectroscopy shows acetyl-CoA synthase binds two substrate CO in multiple binding modes and reveals the importance of a CO-binding ‘alcove’, J. Am. Chem. Soc., 142, 15362-15370.
3. Can M, et al. (2023) Characterization of Methyl- and Acetyl-Ni Intermediates in Acetyl CoA Synthase Formed during Anaerobic CO2 and CO Fixation. J. Am. Chem. Soc.. 145:13696-708.
4. Wiley, S., Griffith, C., Eckert, P., Mueller, A. P., Nogle, R., Simpson, S. D. et al. (2024) An alcove at the acetyl-CoA synthase nickel active site is required for productive substrate CO binding and anaerobic carbon fixation Journal of Biological Chemistry 300, 107503
Additional Public Info:
In-Person Seminar
1901 Vine Street, Beadle Center #103
https://medicine.umich.edu/dept/cmb/stephen-ragsdale-phd
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This event originated in Biochemistry.