Putrescine biosynthesis and export genes are essential for normal growth of avian pathogenic Escherichia coli

Abstract

BackgroundAvian pathogenic Escherichia coli (APEC) is the infectious agent of a wide variety of avian diseases, which causes substantial economic losses to the poultry industry worldwide. Polyamines contribute to the optimal synthesis of nucleic acids and proteins in bacteria. The objectives of this study were to investigate; i) whether APEC E. coli encodes the same systems for biosynthesis and uptake as described for E. coli K12 and ii) the role of polyamines during in vitro growth of an avian pathogenic E. coli strain (WT-ST117- O83:H4T).ResultsFollowing whole genome sequencing, polyamine biosynthesis and export genes present in E. coli MG1655 (K-12) were found to be identical in WT-ST117. Defined mutants were constructed in putrescine and spermidine biosynthesis pathways (ΔspeB, ΔspeC, ΔspeF, ΔspeB/C and ΔspeD/E), and in polyamines transport systems (ΔpotE, ΔyeeF, ΔpotABCD and ΔpotFGHI). Contrary to what was observed for MG1655, the ΔpotE-ST117 mutant was growth attenuated, regardless of putrescine supplementation. The addition of spermidine or orthinine restored the growth to the level of WT-ST117. Growth attenuation after induction of membrane stress by SDS suggested that PotE is involved in protection against this stress. The ΔspeB/C-ST117 mutant was also growth attenuated in minimal medium. The addition of putrescine or spermidine to the media restored growth rate to the wild type level. The remaining biosynthesis and transport mutants showed a growth similar to that of WT-ST117. Analysis by Ultra-High Performance Liquid Chromatography revealed that the ΔspeB/C mutant was putrescine-deficient, despite that the gene speF, which is also involved in the synthesis of putrescine, was expressed.ConclusionsDeletion of the putrescine transport system, PotE, or the putrescine biosynthesis pathway genes speB/C affected in vitro growth of APEC (ST117- O83:H4) strain, but not E. coli MG1655, despite the high similarity of the genetic make-up of biosynthesis and transport genes. Therefore, blocking these metabolic reactions may be a suitable way to prevent APEC growth in the host without disturbing the commensal E. coli population.Electronic supplementary materialThe online version of this article (10.1186/s12866-018-1355-9) contains supplementary material, which is available to authorized users.

Ornithine capture by a translating ribosome controls bacterial polyamine synthesis

“…In conclusion, our data reveal how the ribosome aided by SpeFL functions as a highly selective ornithine sensor to regulate polyamine biosynthesis in pathogenic bacteria like E. coli or S. Typhimurium. Both speF and potE, whose expression is regulated by SpeFL in response to fluctuating ornithine levels, have been linked to biofilm formation and microbial virulence [24][25][26] . However, the exact physiological roles of the speF operon remain unclear.…”

Comparative genomics and metabolomics analysis of Riemerella anatipestifer strain CH-1 and CH-2

“…Putrescine as only one polyamine was identified in two strains. Putrescine is mainly related to biofilm formation 64 and protein synthesis 65 , so putrescine metabolic pathways may be considered as a potential novel target for antibiotics [66][67][68] . The metabolism of putrescine biosynthesis in microorganisms has two alternative pathways.…”

Arginine Decarboxylase Is Essential for Pneumococcal Stress Responses

“…Polyamines are known to be involved in ROS scavenging, pH homeostasis, and regulation of antioxidant systems. Therefore, reduced polyamine synthesis that results in altered levels of intracellular polyamines is expected to render ΔspeA more susceptible to stress [ 4 , 8 , 9 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Indeed, when we characterized the proteome and transcriptome of ΔspeA , we observed a shift in the carbon flow toward the pentose phosphate pathway [ 13 , 14 ], a signature of oxidative stress [ 16 ].…”

“…Increased sensitivity of Δ speA to exogenous H 2 O 2 and superoxide radicals reported here suggests a role of polyamines in pneumococcal oxidative stress responses, which is consistent with earlier reports. Putrescine and spermidine protect cells from ROS by increasing the expression of regulators or genes that encode free-radical scavengers [ 8 , 24 , 25 , 33 ]. Spermine and spermidine are known to scavenge ROS and work synergistically with superoxide dismutase to reduce single-stranded DNA breakages due to ROS [ 25 , 34 , 35 ].…”