Abstract
BackgroundPseudomonas aeruginosa, a Gram-negative, aerobic coccobacillus bacterium is an opportunistic human pathogen and worldwide the fourth most common cause of hospital-acquired infections which are often high mortality such as ventilator-associated pneumoniae. The polyamine metabolism of P. aeruginosa and particularly the deacetylation of acetylpolyamines has been little studied up to now. Results with other bacterial pathogens e.g., Y. pestis suggest that polyamines may be involved in the formation of biofilms or confer resistance against certain antibiotics.ResultsTo elucidate the role of acetylpolyamines and their enzymatic deacetylation in more detail, all three putative acetylpolyamine amidohydrolases (APAHs) from P. aeruginosa have been expressed in enzymatic active form. The APAHs PA0321 and PA1409 are shown to be true polyamine deacetylases, whereas PA3774 is not able to deacetylate acetylated polyamines. Every APAH can hydrolyze trifluoroacetylated lysine-derivatives, but only PA1409 and much more efficiently PA3774 can also process the plain acetylated lysine substrate. P. aeruginosa is able to utilize acetylcadaverine and acetylputrescine as a carbon source under glucose starvation. If either the PA0321 or the PA1409 but not the PA3774 gene is disrupted, the growth of P. aeruginosa is reduced and delayed. In addition, we were able to show that the APAH inhibitors SAHA and SATFMK induce biofilm formation in both PA14 and PAO1 wildtype strains.ConclusionsP. aeruginosa has two functional APAHs, PA0321 and PA1409 which enable the utilization of acetylpolyamines for the metabolism of P. aeruginosa. In contrast, the physiological role of the predicted APAH, PA3774, remains to be elucidated. Its ability to deacetylate synthetic acetylated lysine substrates points to a protein deacetylation functionality with yet unknown substrates.Electronic supplementary materialThe online version of this article (doi:10.1186/s12858-016-0063-z) contains supplementary material, which is available to authorized users.
Highlights
Pseudomonas aeruginosa, a Gram-negative, aerobic coccobacillus bacterium is an opportunistic human pathogen and worldwide the fourth most common cause of hospital-acquired infections which are often high mortality such as ventilator-associated pneumoniae
Exploiting the Pseudomonas Genome Database [22] three putative acetylpolyamine amidohydrolases (APAHs) were found: PA0321, PA1409 and PA3774 which show remarkable sequence similarity to enzymes belonging to the histone deacetylase family
PA0321 and PA1409 form a cluster with the verified functional acetylpolyamine amidohydrolase APAH from M. ramosa, whereas PA3774, HDAH and HDAC6 are grouped in a different cluster (Fig. 1b)
Summary
Pseudomonas aeruginosa, a Gram-negative, aerobic coccobacillus bacterium is an opportunistic human pathogen and worldwide the fourth most common cause of hospital-acquired infections which are often high mortality such as ventilator-associated pneumoniae. Results with other bacterial pathogens e.g., Y. pestis suggest that polyamines may be involved in the formation of biofilms or confer resistance against certain antibiotics. Pseudomonas aeruginosa, a versatile Gram-negative bacterium, is an opportunistic human pathogen that is worldwide the fourth most common cause of hospital-acquired infections of the gastrointestinal, urinary or respiratory tracts. These infections often result in fatal courses of disease. One of them was identified by Lu et al and proposed to be an ABC transporter system for spermidine uptake [16] This polyamine transport system was linked to the type III secretion system, which is a major virulence factor in bacteria [17]. Like other bacterial APAHs, e.g., from Mycoplana ramosa, the corresponding protein sequences from P. aeruginosa belong to the histone deacetylase family, and the amino acids lining the active site and chelating the catalytic zinc ion are highly conserved
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