A bacterial biosynthetic pathway for methylated furan fatty acids

Rachelle A S Lemke; Stephanie M Olson; Kaitlin Morse; Steven D Karlen; Alan Higbee; Emily T Beebe; John Ralph; Joshua J Coon; Brian G Fox; Timothy J Donohue

doi:10.1074/jbc.RA120.013697

A bacterial biosynthetic pathway for methylated furan fatty acids

J Biol Chem. 2020 Jul 17;295(29):9786-9801. doi: 10.1074/jbc.RA120.013697. Epub 2020 May 20.

Authors

Rachelle A S Lemke^{1

2

3}, Stephanie M Olson^{1

2

3}, Kaitlin Morse^{2

3}, Steven D Karlen^{2

3

4}, Alan Higbee^{2

3

5}, Emily T Beebe³, John Ralph^{2

3

4}, Joshua J Coon^{3

5

6}, Brian G Fox^{2

3

4}, Timothy J Donohue^{7

2

3}

Affiliations

¹ Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, USA.
² Wisconsin Energy Institute, University of Wisconsin, Madison, Wisconsin, USA.
³ Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin, USA.
⁴ Department of Biochemistry, University of Wisconsin, Madison, Wisconsin, USA.
⁵ Genome Center of Wisconsin, University of Wisconsin, Madison, Wisconsin, USA.
⁶ Department of Biomolecular Chemistry, University of Wisconsin, Madison, Wisconsin, USA.
⁷ Department of Bacteriology, University of Wisconsin, Madison, Wisconsin, USA tdonohue@bact.wisc.edu.

Abstract

Fatty acids play many important roles in cells and also in industrial processes. Furan fatty acids (FuFAs) are present in the lipids of some plant, fish, and microbial species and appear to function as second messengers in pathways that protect cells from membrane-damaging agents. We report here the results of chemical, genetic, and synthetic biology experiments to decipher the biosynthesis of the monomethylated FuFA, methyl 9-(3-methyl-5-pentylfuran-2-yl) nonanoate (9M5-FuFA), and its dimethyl counterpart, methyl 9-(3,4-dimethyl-5-pentylfuran-2-yl) nonanoate (9D5-FuFA), in two α-proteobacteria. Each of the steps in FuFA biosynthesis occurs on pre-existing phospholipid fatty acid chains, and we identified pathway intermediates and the gene products that catalyze 9M5-FuFA and 9D5-FuFA synthesis in Rhodobacter sphaeroides 2.4.1 and Rhodopseudomonas palustris CGA009. One previously unknown pathway intermediate was a methylated diunsaturated fatty acid, (10E,12E)-11-methyloctadeca-10,12-dienoic acid (11Me-10t,12t-18:2), produced from (11E)-methyloctadeca-11-enoic acid (11Me-12t-18:1) by a newly identified fatty acid desaturase, UfaD. We also show that molecular oxygen (O₂) is the source of the oxygen atom in the furan ring of 9M5-FuFA, and our findings predict that an O₂-derived oxygen atom is incorporated into 9M5-FuFA via a protein, UfaO, that uses the 11Me-10t,12t-18:2 fatty acid phospholipid chain as a substrate. We discovered that R. palustris also contains a SAM-dependent methylase, FufM, that produces 9D5-FuFA from 9M5-FuFA. These results uncover the biochemical sequence of intermediates in a bacterial pathway for 9M5-FuFA and 9D5-FuFA biosynthesis and suggest the existence of homologs of the enzymes identified here that could function in FuFA biosynthesis in other organisms.

Keywords: cell signaling; fatty acid metabolism; fatty acid modification; fatty acyl methylase; furan fatty acid; lipid metabolism; oxygenated fatty acids; phospholipid; polyunsaturated fatty acid; polyunsaturated fatty acid (PUFA); α-proteobacteria.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Biosynthetic Pathways*
Fatty Acids / biosynthesis*
Fatty Acids / genetics
Furans / metabolism*
Rhodobacter sphaeroides / genetics
Rhodobacter sphaeroides / metabolism*
Rhodopseudomonas / genetics
Rhodopseudomonas / metabolism*

Substances

Fatty Acids
Furans

Supplementary concepts

Rhodopseudomonas palustris