biostudies-literatureChen PYNCRR NIH HHSNational Institutes of HealthOffice of ScienceNIGMS NIH HHS595-611https://www.ebi.ac.uk/biostudies/studies/S-EPMC6508887biostudies-literatureUnknown3(2)2-oxoglutarate:ferredoxin oxidoreductase (OGOR) is a thiamine pyrophosphate (TPP) and [4Fe-4S] cluster-dependent enzyme from the reductive tricarboxylic acid (rTCA) cycle that fixes CO₂ to succinyl-CoA, forming 2-oxoglutarate and CoA. Here we report an OGOR from the rTCA cycle of <i>Magnetococcus marinus</i> MC-1, along with all three potential ferredoxin (Fd) redox partners. We demonstrate <i>Mm</i>OGOR operates bidirectionally (both CO₂-fixing and 2-oxoglutarate oxidizing), and that only one Fd (<i>Mm</i>Fd1) supports efficient catalysis. Our 1.94-Å and 2.80-Å resolution crystal structures of native and substrate-bound forms of <i>Mm</i>OGOR reveal the determinants of substrate specificity and CoA-binding in an OGOR, and illuminate the [4Fe-4S] cluster environment, portraying the electronic conduit allowing <i>Mm</i>Fd1 to be wired to the bound-TPP. Structural and biochemical data further identify Glu45α as a mobile residue that impacts catalytic bias toward CO₂-fixation although it makes no direct contact with TPP-bound intermediates, indicating that reaction directionality can be tuned by second layer interactions. (149 of 150 words limit).JouleA reverse TCA cycle 2-oxoacid:ferredoxin oxidoreductase that makes C-C bonds from CO₂.PMC6508887R35 GM126982DE-AC02-06CH11357BES DE-SC0012598S10 RR029205P41 GM103403R01 GM069857Chen PYElliott SJLi BDrennan CLfalseA reverse TCA cycle 2-oxoacid:ferredoxin oxidoreductase that makes C-C bonds from CO₂.2-oxoglutarate:ferredoxin oxidoreductase (OGOR) is a thiamine pyrophosphate (TPP) and [4Fe-4S] cluster-dependent enzyme from the reductive tricarboxylic acid (rTCA) cycle that fixes CO₂ to succinyl-CoA, forming 2-oxoglutarate and CoA. Here we report an OGOR from the rTCA cycle of <i>Magnetococcus marinus</i> MC-1, along with all three potential ferredoxin (Fd) redox partners. We demonstrate <i>Mm</i>OGOR operates bidirectionally (both CO₂-fixing and 2-oxoglutarate oxidizing), and that only one Fd (<i>Mm</i>Fd1) supports efficient catalysis. Our 1.94-Å and 2.80-Å resolution crystal structures of native and substrate-bound forms of <i>Mm</i>OGOR reveal the determinants of substrate specificity and CoA-binding in an OGOR, and illuminate the [4Fe-4S] cluster environment, portraying the electronic conduit allowing <i>Mm</i>Fd1 to be wired to the bound-TPP. Structural and biochemical data further identify Glu45α as a mobile residue that impacts catalytic bias toward CO₂-fixation although it makes no direct contact with TPP-bound intermediates, indicating that reaction directionality can be tuned by second layer interactions. (149 of 150 words limit).2019-01-01T00:00:00Z2019 Feb2024-11-11T19:16:05.661Z2020-10-29T10:36:37ZS-EPMC65088873108094310.1016/j.joule.2018.12.006