A Canonical Biotin Synthesis Enzyme, 8-Amino-7-Oxononanoate Synthase (BioF), Utilizes Different Acyl Chain Donors in Bacillus subtilis and Escherichia coli

Abstract

BioF (8-amino-7-oxononanoate synthase) is a strictly conserved enzyme that catalyzes the first step in assembly of the fused heterocyclic rings of biotin. The BioF acyl chain donor has long been thought to be pimeloyl-CoA. Indeed, the and enzymes have been shown to condense pimeloyl-CoA with l-alanine in a pyridoxal 5'-phosphate-dependent reaction with concomitant CoA release and decarboxylation of l-alanine. However, recent studies of and suggested that the BioF proteins of the two bacteria could have different specificities for pimelate thioesters in that BioF may utilize either pimeloyl coenzyme A (CoA) or the pimelate thioester of the acyl carrier protein (ACP) of fatty acid synthesis. In contrast, BioF seemed likely to be specific for pimeloyl-CoA and unable to utilize pimeloyl-ACP. We now report genetic and data demonstrating that BioF specifically utilizes pimeloyl-CoA. Biotin is an essential vitamin required by mammals and birds because, unlike bacteria, plants, and some fungi, these organisms cannot make biotin. Currently, the biotin included in vitamin tablets and animal feeds is made by chemical synthesis. This is partly because the biosynthetic pathways in bacteria are incompletely understood. This paper defines an enzyme of the pathway and shows that it differs from that of in the ability to utilize specific precursors. These bacteria have been used in biotin production and these data may aid in making biotin produced by biotechnology commercially competitive with that produced by chemical synthesis.

α-proteobacteria synthesize biotin precursor pimeloyl-ACP using BioZ 3-ketoacyl-ACP synthase and lysine catabolism

“…Previous studies have shown that B. subtilis BioF specifically accepts only pimeloyl-CoA as acyl donor, whereas pimeloyl-ACP is inactive both in vivo and in vitro 12 . In contrast, E. coli BioF accepts either of the pimeloyl-thioesters, although pimeloyl-ACP is strongly favored.…”

“…After preparation of the resting cell suspensions in minimal medium lacking a carbon source, various dicarboxylic acids were added followed by incubation for 12-16 h. The culture media were concentrated tenfold and spotted on plates containing strain E. coli ER90 to assay for biotin/DTB production. Unlike B. subtilis which directly incorporates exogenous pimelate into biotin 6,12 , A. tumefaciens failed to incorporate pimelate into biotin/DTB but rather used glutarate or compounds readily converted to glutarate to synthesize the pimelate precursor (Fig. 8).…”

“…Indeed, the Gram-positive bacterium B. subtilis encodes a cytochrome P450 oxidoreductase called BioI that can cleave a long acyl-ACP chain into pimeloyl-ACP 10,11 . However, B. subtilis BioI is an enigma because it is not essential for biotin synthesis and makes a product that cannot be utilized by BioF, the next enzyme of the pathway 12 . Instead the pimeloyl-CoA ligase (BioW) plays a key role in biotin synthesis 12 (Fig.…”

“…However, B. subtilis BioI is an enigma because it is not essential for biotin synthesis and makes a product that cannot be utilized by BioF, the next enzyme of the pathway 12 . Instead the pimeloyl-CoA ligase (BioW) plays a key role in biotin synthesis 12 (Fig. 1b).…”

Engineering of vitamin prototrophy in Clostridium ljungdahlii and Clostridium autoethanogenum

“…BioW was reported essential in B. subtilis and converts pimelate to pimeloyl-CoA (Manandhar and Cronan 2017). Furthermore, it was found that BioF of B. subtilis specifically used pimeloyl-CoA, whereas E. coli BioF also used pimeloyl-[acp] (Manandhar and Cronan 2018). Recently, it was reported that C. acetobutylicum was able to grow in defined medium without biotin (Li et al 2013; Yang et al 2016), although carry-over of biotin in the method used cannot be excluded.…”