A Caltech Library Service

Bacterial Form I’ rubisco has smaller carbon isotope fractionation than its Form I counterpart

Wang, Renée Z. and Liu, Albert K. and Banda, Douglas M. and Fischer, Woodward W. and Shih, Patrick M. (2023) Bacterial Form I’ rubisco has smaller carbon isotope fractionation than its Form I counterpart. . (Unpublished)

[img] PDF - Submitted Version
Creative Commons Attribution Non-commercial No Derivatives.

[img] PDF (Supplemental Figures and Tables) - Supplemental Material
Creative Commons Attribution Non-commercial No Derivatives.


Use this Persistent URL to link to this item:


Form I rubiscos evolved in Cyanobacteria ≥2.5 billion years ago and are enzymatically unique due to the presence of small subunits (RbcS) that cap both ends of an octameric large subunit (RbcL) rubisco assembly to form a hexadecameric (L₈S₈) holoenzyme. Although RbcS was previously thought to be integral to Form I rubisco stability, the recent discovery of a closely related sister clade of octameric rubiscos (Form I’; L₈) demonstrates that the enzyme complex assembles without small subunits (Banda et al. 2020). Rubisco also displays a kinetic isotope effect (KIE) where the 3PG product is depleted in ¹³C relative to ¹²C. In Cyanobacteria only two Form I KIE measurements exist, making interpretation of bacterial carbon isotope data difficult. To aid comparison, we measured in vitro the KIEs of Form I’ (Candidatus Promineofilum breve) and Form I (Synechococcus elongatus PCC 6301) rubiscos and found the KIE to be smaller in the L₈ rubisco (16.25 ± 1.36‰ vs. 22.42 ± 2.37‰ respectively). Therefore, while small subunits may not be necessary for protein stability, they may affect the KIE. Our findings may provide insight into the function of RbcS and allow more refined interpretation of environmental carbon isotope data.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Wang, Renée Z.0000-0003-3994-3244
Liu, Albert K.0000-0001-9500-0449
Banda, Douglas M.0000-0001-6198-2923
Fischer, Woodward W.0000-0002-8836-3054
Shih, Patrick M.0000-0002-2119-3345
Additional Information:The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. Data Availability Statement. All data used in this study are presented in the supplement. The authors have declared no competing interest.
Group:Division of Geological and Planetary Sciences
Record Number:CaltechAUTHORS:20230316-182052000.9
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:120128
Deposited By: George Porter
Deposited On:22 Mar 2023 16:35
Last Modified:22 Mar 2023 16:35

Repository Staff Only: item control page