Characterization and a role of Pseudomonas aeruginosa spermidine dehydrogenase in polyamine catabolism

Abstract

Pseudomonas aeruginosa PAO1 has two possible catabolic pathways of spermidine and spermine; one includes the spuA and spuB products with unknown functions and the other involves spermidine dehydrogenase (SpdH; EC 1.5.99.6) encoded by an unknown gene. The properties of SpdH in P. aeruginosa PAO1 were characterized and the corresponding spdH gene in this strain identified. The deduced SpdH (620 residues, calculated M r of 68 861) had a signal sequence of 28 amino acids at the amino terminal and a potential transmembrane segment between residues 76 and 92, in accordance with membrane location of the enzyme. Purified SpdH oxidatively cleaved spermidine into 1,3-diaminopropane and 4-aminobutyraldehyde with a specific activity of 37 units (mg protein) "1 and a K m value of 36 mM. The enzyme also hydrolysed spermine into spermidine and 3-aminopropanaldehyde with a specific activity of 25 units (mg protein) "1 and a K m of 18 mM. Knockout of spdH had no apparent effect on the utilization of both polyamines, suggesting that this gene is minimally involved in polyamine catabolism. However, when spdH was fused to the polyamine-inducible promoter of spuA, it fully restored the ability of a spuA mutant to utilize spermidine. It is concluded that SpdH can perform a catabolic role in vivo, but P. aeruginosa PAO1 does not produce sufficient amounts of the enzyme to execute this function.

Comparative single-cell genomics reveals potential ecological niches for the freshwater acI Actinobacteria lineage

“…Other transporters that the 11 acI SAGs have in common, include ABC-type transporters for ribose/xylose/ arabinose/galactoside, polyamines, dipeptides and branched-chain amino acids ( Table 2). The polyamine transporters are likely being used for putrescine uptake, as the SAGs harbor downstream pathways for its eventual conversion to succinate via the transamination pathway (Dasu et al, 2006;Chou et al, 2008); (Figure 2). Genes for the uptake of carboxylic acids in acI-A1, acI-A7 and acI-B1 were not found in any of the sequenced genomes, consistent with MAR-FISH-based studies (Buck et al, 2009;Salcher et al, 2013).…”

Functional Characterization of Seven γ-Glutamylpolyamine Synthetase Genes and the bauRABCD Locus for Polyamine and β-Alanine Utilization in Pseudomonas aeruginosa PAO1

“…Without ␥-glutamylation, spermidine dehydrogenase encoded by the spdH gene was reported to catalyze oxidative cleavage of Spd into DAP and 4-aminobutyraldehyde, as well as spermine, into Spd and 3-aminopropanaldehyde (5). However, synthesis of this enzyme was not inducible by exogenous polyamines, and the spdH knockout mutant grew normally on Spd and spermine.…”

γ-Glutamyl Spermine Synthetase PauA2 as a Potential Target of Antibiotic Development against Pseudomonas aeruginosa

“…One likely candidate for the second transport system is encoded by PA3607-PA3610, which were annotated as potABCD based on sequence similarities to the E. coli counterparts (10) that encode components of an Spd transport system. Dasu et al have reported a periplasmic Spd/Spm dehydrogenase (3). Although this enzyme alone may not have any significant contribution to polyamine catabolism since its expression level was constitutively low and not inducible by polyamines, it may provide some degree of protection against Spm/Spd toxicity in the spuF mutant.…”

“…permine (Spm), along with spermidine (Spd) and putrescine (Put), is one of the three most common polyamines in human and other eukaryotic cells (3). Because of the positively charged nature, polyamines are believed to serve as ubiquitous structural components in cells through interactions with RNA and DNA macromolecules.…”