1 Supplementary Information

2 Electron transfer complexes in the gut dictate high abundance circulating

3 metabolites

4 Yuanyuan Liu1,2, William Van Treuren2, Bi-Huei Hou1,2, Steven K. Higginbottom2, Justin

5 L. Sonnenburg2,3,4, and Dylan Dodd1,2†

6

7 1Department of Pathology Stanford University School of Medicine, Stanford, CA, USA;

8 2Department of Microbiology and Immunology, Stanford University School of Medicine,

9 Stanford, CA, USA; 3Chan Zuckerburg Biohub, San Francisco, CA, USA; 4Center for

10 Human Microbiome Studies, Stanford, CA, USA.

11

12 † Correspondence: [email protected]

13 14 Supplementary Tables Supplementary Table 1. Estimates of ATP levels during Stickland metabolism of Phe. Phenylalanine disproportionation Considerations Oxidative Pathway Reductive Pathway Stoichiometry for redox 1 mole Phe 2 moles Phe balance NADH reducing equivalents 2 NADH produced (total) 2 NADH produced 4 NADH consumed Net: 2 NADH consumed ATP from substrate level 1 ATP phosphorylation Ferredoxin reduced (2 e- 1 mole Fdred 2 moles Fdred reduction) Protons translocated through Rnf complex 2 protons 4 protons (assuming 2 protons per mole Fdred)a ATP from ETP (assuming 4 0.5 ATP 1 ATP protons per mole ATP)a Total ATP 1.5 ATP 1 ATP Percentage of total ATP 60% 40% a Estimates are from Buckel and Thauer25. 15

16 Supplementary Table 2. Homologs of electron transfer complexes identified by BLASTp Query (% identity # hits # Phyla (Phylum names) # Families (family names) cutoff)a,b,c Clostridium 551 5 phyla (, 19 families (Clostridiaceae, Lachnospiraceae, kluyveri Bcd , Ruminococcaceae, Christensenellaceae, (65%) , Peptostreptococcaceae, Oscillospiraceae, , Proteinivoraceae, Peptoniphilaceae, ) Eubacteriaceae, Thermoanaerobacteraceae, Tissierellaceae, Thermotogaceae, Fervidobacteriaceae, Marinifilaceae, Porphyromonadaceae, Odoribacteraceae, Rikenellaceae, Moraxellaceae, Fusobacteriaceae) Clostridium 53 1 phylum (Firmicutes) 4 families (Clostridiaceae, Lachnospiraceae, sporogenes AcdA Peptostreptococcaceae, Eubacteriaceae) (65%) Clostridium 99 3 phyla (Firmicutes, 6 families (Clostridiaceae, Lachnospiraceae, sporogenes AcdB Proteobacteria, Peptostreptococcaceae, Peptoniphilaceae, (65%) Fusobacteria) Moraxellaceae, Fusobacteriaceae) Clostridium 179 3 phyla (Firmicutes, 9 families (Clostridiaceae, Lachnospiraceae, sticklandii PrdA Proteobacteria, Peptostreptococcaceae, Eubacteriaceae, (65%) Fusobacteria) Ruminococcaceae, Halanaerobiaceae, Veillonellaceae, Moraxellaceae, Fusobacteriaceae) Clostridium 108 2 phyla (Firmicutes, 9 families (Clostridiaceae, Peptostreptococcaceae, sporogenes FldZ Proteobacteria) Lachnospiraceae, Paenibacillaceae, (65%) Pectobacteriaceae, Saccharospirillaceae, Vibrionaceae, Methylocystaceae, Hyphomicrobiaceae) Clostridium 558 5 phyla (Firmicutes, 17 families (Clostridiaceae, Vallitaleaceae, sporogenes RnfB , , Eubacteriaceae, Lachnospiraceae, (50%) Bacteroidetes, Defluviitaleaceae, Peptostreptococcaceae, Proteobacteria) Syntrophomonadaceae, Ruminococcaceae, Caldicoprobacteraceae, Peptococcaceae, Thermoanaerobacteraceae, Peptoniphilaceae, Tissierellaceae, Anaerolineaceae, Synergistaceae, Bacteroidaceae, Enterobacteriaceae) aGenBank accession numbers for query proteins are as follows: Bcd, EDK32509.1; AcdA, EDU39257.1; AcdB, EDU36591.1; FldZ, EDU36612.1; RnfB, EDU37753.1. bPercent amino acid identity values were determined by first perform performing BLASTp searches of the GenBank database such that known homologs from distantly related organisms were retrieved in the results. cA query coverage cutoff of 80% was also applied. 17 Supplementary Table 3. Primers used in this study. Sequencing primers for ClosTron mutants Gene (Locus ID) Targeted Regiona Sequencing Primersb,c rnfB (CLOSPO_00568) 422s rnfBF: TTTACCAGGAGCTAACTGTG rnfBR: TGGCAAATATCTTTAACAGC rnfE (CLOSPO_00570) 61s rnfEF: TTTAGAAGTTGTTAAGACAGC rnfBR: TATTGAAGATACTGGACCAT

Q-PCR primers Primer Orientation Sequence (5′→3′) c Clostridium sporogenes total Forward TTGGCTCTGCACCGGGAATC Reverse CTGCAAACGCCGTCCCTCTT rnfB mutant Forward AGAGCAACCCTAGTGTTCGGTGA Reverse TTGAAAGCCATGCGTCTGACATCT a Targeting regions were designed using the Intron design tool on the ClosTron website (http://www.clostron.com/clostron2.php). The regions listed indicate the nucleotide position within the gene where the intron is inserted and the a/s designation indicates whether the intron integrates in the antisense or sense strand. b Primers were designed to amplify the region containing the expected intron after integration. c Primers were synthesized by Integrated DNA Technologies (Coralville, IA). 18 19 Supplementary Figures

20

21 22 Supplementary Figure 1. Acetate supplementation influences synergism of 23 branched chain amino acids with proline and trans-4-hydroxyproline. C. 24 sporogenes was grown in basal medium devoid of acetate, with the indicated substrates 25 (25 mM) for 48 h and the maximum optical density at 600nm was recorded using a 26 microplate spectrophotometer. 27 28 Supplementary Figure 2. Reductive metabolism of phenyllactic acid is coupled to 29 ATP formation involving acdA. A) DL-Phenyllactic acid was added (1 mM) to resting 30 cell suspensions of C. sporogenes, and ATP levels were measured at indicated 31 timepoints using a luciferase based assay. B) Reductive (PPA) and oxidative (PAA) 32 pathway end products were measured by tandem mass spectrometry during D- 33 phenyllactic acid metabolism. PPA, phenylpropionic acid; PAA, phenylacetic acid. C-D) 34 Phenylacetic acid (C) or phenylpropionic acid (D) were added (1 mM) to resting cell 35 suspensions of C. sporogenes, and ATP levels were measured at indicated timepoints 36 using a luciferase based assay. E) D- or L-phenyllactic acid was added (1 mM) to 37 resting cell suspensions of C. sporogenes, and ATP levels were measured at indicated 38 timepoints using a luciferase based assay. F) DL-phenyllactic acid was added (1 mM) to 39 resting cell suspensions of WT or acdA mutant C. sporogenes, and ATP levels were 40 measured at indicated timepoints using a luciferase based assay. G) Pathways for 41 oxidative and reductive metabolism of phenylalanine. For A-F, experiments were 42 repeated independently three times and representative data are shown. 43 44 Supplementary Figure 3. Proposed ATP yield from the Stickland reaction 45 involving disproportionation of phenylalanine. The Gibbs free energy was 46 calculated from the free energy of formation for reactants and products as given in 47 Thauer et al.26 with the following substitutions (alanine for phenylalanine; acetate for 48 phenylacetate; propionate for phenylpropionate). These estimates suggest that the 49 oxidative pathway contributes 1.5 ATP (1 via substrate level phosphorylation and 0.5 via 50 electron transport phosphorylation), and the reductive pathway contributes 1 ATP (via 51 electron transport phosphorylation).

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