Journal: bioRxiv
Article Title: Form IF Rubiscos include highly active, specific, and small subunit-independent enzymes
doi: 10.64898/2026.03.18.712719
Figure Lengend Snippet: (A) Reduced phylogenetic tree of Rubisco with the Form IF Rubiscos clade (teal), branching from Form IA/B Rubiscos highlighted in green. (B) Phylogenetic tree of the Form IF clade. Proteins of interest are denoted on the tree. Form IF-1 and IF-2 belong to the Gaiellales bacterium clade, Form IF-3 can be found in a Chloroflexi bacterium, Form IF-4 in an Anaerolineales bacterium and Form IF-5 in a Limnochordaceae bacterium. (C) Metagenomes of the hosts of the proteins of interest were searched for known Rubisco chaperones and activases. Dark green denotes presence of a gene encoding a homolog (with a BLAST E-value of <10 −10 , red fields denote the lack of a gene encoding a homolog). None of the hosts harbor enzymes like known Rubisco chaperones. (D) Size-exclusion chromatography revealed the hexadecameric complex, as indicated by the calculated L 8 S 8 retention volume. (E) Mass Photometry showing L 8 S 8 formation for Form IF-3 (green) Form IF-4 (orange), Form IF-5 (coral) and mixed results of L 8 /L 8 S 8 formation for Form IF-1 (dark blue) and Form IF-2 (turquoise). (F) Cryo-EM structure of IF-1. The LSU is shown in blue and light blue, the SSU in beige. IF-1 PDB: 28VR. (G) Crystal structure of IF-2. LSU is shown turquoise and light turquoise the SSU in ocher. IF-2 PDB: 28VS.
Article Snippet: Unbound [ 14 C]-2-CABP was separated from CABP-bound Rubisco using 10 mL Sephadex G50 Fine resin in a glass chromatography column (Biorad Econo Column #7370732).
Techniques: Size-exclusion Chromatography, Cryo-EM Sample Prep
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