Figure 1.
The biosynthetic gene cluster for the yellow pigments of L. enzymogenes OH11.
The small arrow on ORF17 indicates the transposon insertion site in the initial “white” mutant OH11B.
Figure 2.
HPLC of the yellow pigments of L. enzymogenes OH11.
A. wild type; B. ΔORF17 (KAS I); C. ΔORF6 (ACP); D. ΔORF10 (outer membrane lipoprotein carrier protein); E. ΔORF13 (KR); F. xanthomonadin extract from Xanthomonas campestris pv. campestris (as a reference).
Figure 3.
The proposed chemical structure and biosynthetic mechanism for the yellow pigments.
A. The proposed chemical structure of the main yellow pigment of L. enzymogenes OH11 and xanthomonadin I from Xanthomonas campestris pv. campestris. B. The proposed biosynthetic pathway for Lysobacter pigments. The type II PKS consists of ORF17/16, 9, 6, 13, and 12/8, corresponding to KS/CLF, AT, ACP, KR, and DH/DH, respectively. ORF5 (pteridine-dependent dioxygenase) is proposed to add the 3-hydroxy to benzoic acid to form the starter unit of biosynthesis. An unknown thioesterase (TE) releases the initial aryl octaene intermediate, which is methylated by an unknown methyltransferease (MT) and 4-hydroxylated by a putative hydroxylase (or ORF5).
Figure 4.
HPLC of the yellow pigments of L. enzymogenes OH11.
A. ΔORF5 (Pteridine-dependent dioxygenase); B. ΔORF5 fed with 3-hydroxybenzoic acid.
Figure 5.
The highly conserved ORF16–ORF17 pair from a number of selected examples of microbial genomes.
For each of the biosynthetic gene clusters, only part of the cluster is shown. The organization of the ORFs flanking ORF16–ORF17 is not conserved, except the blue-colored ORF15 homologs (dolichyl-phosphate mannose synthase, absent in Variovorax paradoxus) and the green-colored halogenase genes (absent in L. enzymogenes and Xylella fastidiosa).
Figure 6.
HPLC of the yellow pigment production in three ORF16 mutants of L. enzymogenes OH11.
A. ΔORF16; B. ORF16 Q166A; C. ORF16 S120A. The phenotype of the wild type (D), ORF16 Q166A (E), and ORF16 S120A (F) is also shown.
Figure 7.
The survival rate of the wild type (OH11) and four mutants upon exposure to UV254 (A), visible light (B), or H2O2 (C).
In A and B, each data point represents the average of two replicates; in C, each data point is of three replicates with deviation bars shown.