Biological Functions of ilvC in Branched-Chain Fatty Acid Synthesis and Diffusible Signal Factor Family Production in Xanthomonas campestris

Abstract

In bacteria, the metabolism of branched-chain amino acids (BCAAs) is tightly associated with branched-chain fatty acids (BCFAs) synthetic pathways. Although previous studies have reported on BCFAs biosynthesis, more detailed associations between BCAAs metabolism and BCFAs biosynthesis remain to be addressed. In this study, we deleted the ilvC gene, which encodes ketol-acid reductoisomerase in the BCAAs synthetic pathway, from the Xanthomonas campestris pv. campestris (Xcc) genome. We characterized gene functions in BCFAs biosynthesis and production of the diffusible signal factor (DSF) family signals. Disruption of ilvC caused Xcc to become auxotrophic for valine and isoleucine, and lose the ability to synthesize BCFAs via carbohydrate metabolism. Furthermore, ilvC mutant reduced the ability to produce DSF-family signals, especially branched-chain DSF-family signals, which might be the main reason for Xcc reduction of pathogenesis toward host plants. In this report, we confirmed that BCFAs do not have major functions in acclimatizing Xcc cells to low temperatures.

RpoN1 and RpoN2 play different regulatory roles in virulence traits, flagellar biosynthesis, and basal metabolism in Xanthomonas campestris

“…DSF family signal production was further studied in NYG medium. All the strains produced DSF family signals, namely, cis ‐11‐methyl‐2‐dodecenoic acid (DSF), cis ‐2‐dodecenoic acid (BDSF), and cis ‐10‐methyl‐2‐dodecenoic acid (IDSF), but DSF was the main signal produced under these conditions (Figure 7d–f), consistent with the result of a previous report (Zhou et al , 2015b; Li et al , 2017). However, the amounts of each DSF family signal produced by the mutant strain Δ rpfC Δ rpoN1 and double‐mutant strain Δ rpfC Δ rpoN1N2 were significantly higher than those produced by the Xc1 Δ rpfC strain ( p < .001).…”

“…Fatty acids and DSF family QS signals are critical secondary metabolites for bacterial physiological metabolism (Zhou et al , 2015a; Li et al , 2017; Hu et al ., 2018). In this study, in‐frame deletion of rpoN1 led to significantly reduced production of branched‐chain amino acids (BCAAs) and increased production of DSF family QS signalling molecules, especially cis ‐11‐methyl‐2‐dodecenoic acid.…”

“…In this study, in‐frame deletion of rpoN1 led to significantly reduced production of branched‐chain amino acids (BCAAs) and increased production of DSF family QS signalling molecules, especially cis ‐11‐methyl‐2‐dodecenoic acid. The precursors of the DSF family signals originate from the fatty acid synthesis pathway (Yu et al , 2016; Li et al , 2017). However, BCAAs are the primary precursors for the synthesis of BCFAs (Zhu et al , 2005).…”

“…Protein expression and purification were performed as described previously (Li et al , 2017). To clone the Xcc rpoN1 and Xcc rpoN2 genes, genomic DNA extracted from X. campestris was used for PCR amplification with Pfu DNA polymerase using the primers listed in Table .…”

Two Functional Fatty Acyl Coenzyme A Ligases Affect Free Fatty Acid Metabolism To Block Biosynthesis of an Antifungal Antibiotic in Lysobacter enzymogenes

“…Protein expression and purification were performed as described previously (36). To clone the Le rpfB1 and Le rpfB2 genes, genomic DNA extracted from L. enzymogenes was used for PCR amplification using Pfu DNA polymerase, and the primers are listed in on July 10, 2020 by guest http://aem.asm.org/ Downloaded from Table 3.…”