Utilization of geraniol is dependent on molybdenum in Pseudomonas aeruginosa: evidence for different metabolic routes for oxidation of geraniol and citronellol

Abstract

Mini-Tn5-induced mutants with defects in utilization of linear terpenes such as citronellol, geraniol, citronellate and/or geranylate were isolated from Pseudomonas aeruginosa. One mutant was unable to utilize geraniol but showed wild-type growth with the three other acyclic terpenes tested. The Tn5 insertion site of the mutant was determined by DNA sequencing. Comparison with the P. aeruginosa genome sequence revealed that PA3028, an ORF with high similarity on the amino acid level to molybdenum cofactor biosynthesis protein A2 (encoded by moeA2), was the target of mini-Tn5 in the mutant. Disruption of moeA2 in P. aeruginosa PAO1 wild-type by insertion mutagenesis resulted in the same geraniol-minus phenotype. The ability to utilize geraniol was restored to the mutant by conjugative transfer of PCR-cloned wild-type moeA2 on a broad-host-range plasmid. Growth of P. aeruginosa PAO1 on geraniol and geranial, but not on citronellol, citronellate or geranylate, was inhibited by the presence of 10 mM tungstate, a molybdenum-specific inhibitor. Inhibition by tungstate was prevented by addition of molybdate. The results indicate that at least one step in the oxidation of geraniol to geranic acid (geranial oxidation) is a molybdenum-dependent reaction in P. aeruginosa and is different from the molybdenum-independent oxidation of citronellol to citronellate.

Microbial monoterpene transformations—a review

“…Citronellol degradation is reported for many Pseudomonas strains, including P. aeruginosa PAO1 (ATCC 15692), P. mendocina (ATCC 25411), and P. delhiensis (DSM 18900) (Cantwell et al, 1978; Prakash et al, 2007; Förster-Fromme and Jendrossek, 2010). Among the few reactions described in detail is a molybdenum dependent dehydrogenase responsible for the geranial oxidation to geranylate in P. aeruginosa PAO1 (Höschle and Jendrossek, 2005). …”

Identification of Genes and Proteins Necessary for Catabolism of Acyclic Terpenes and Leucine/Isovalerate in Pseudomonas aeruginosa

“…Transposon mutagenesis with pUTminiTn5-Tc and identification and sequencing of transposon insertion fragments were performed as described previously (21). Gene disruptions were carried out using pKnockout-G (35) as described previously (20).…”

Identification of the aceA gene encoding isocitrate lyase required for the growth of Pseudomonas aeruginosa on acetate, acyclic terpenes and leucine

“…Assimilation of acyclic monoterpenes (citronellol) has been shown to occur in pseudomonads such as Pseudomonas citronellolis, Pseudomonas mendocina and Pseudomonas aeruginosa (Cantwell et al, 1978). The genetic determinants of this pathway were first identified in P. aeruginosa as the gny and mcc gene clusters (for geranyl-CoA and 3-methylcrotonyl-CoA catabolism, respectively) (Díaz-Pérez et al, 2004); they were later renamed as the liu and atu gene clusters, respectively (for leucine/isovalerate utilization and acyclic terpenes utilization, respectively) in P. aeruginosa (Hoschle & Jendrossek, 2005;Aguilar et al, 2006), and recently in P. citronellolis . The acyclic monoterpenes catabolic pathway is encoded by several gene clusters located in different regions of the PAO1 chromosome (Aguilar et al, 2006).…”