The Putrescine Importer PuuP of Escherichia coli K-12

Abstract

The Puu pathway is a putrescine utilization pathway involving gamma-glutamyl intermediates. The genes encoding the enzymes of the Puu pathway form a gene cluster, the puu gene cluster, and puuP is one of the genes in this cluster. In Escherichia coli, three putrescine importers, PotFGHI, PotABCD, and PotE, were discovered in the 1990s and have been studied; however, PuuP had not been discovered previously. This paper shows that PuuP is a novel putrescine importer whose kinetic parameters are equivalent to those of the polyamine importers discovered previously. A puuP ؉ strain absorbed up to 5 mM putrescine from the medium, but a ⌬puuP strain did not. E. coli strain MA261 has been used in previous studies of polyamine transporters, but PuuP had not been identified previously. It was revealed that the puuP gene of MA261 was inactivated by a point mutation. When E. coli was grown on minimal medium supplemented with putrescine as the sole carbon or nitrogen source, only PuuP among the polyamine importers was required. puuP was expressed strongly when putrescine was added to the medium or when the puuR gene, which encodes a putative repressor, was deleted. When E. coli was grown in M9-tryptone medium, PuuP was expressed mainly in the exponential growth phase, and PotFGHI was expressed independently of the growth phase.

A Novel Putrescine Importer Required for Type 1 Pili-driven Surface Motility Induced by Extracellular Putrescine in Escherichia coli K-12

“…Gene disruption of speAB, speC, potABCD, potE, potFGHI, ydcSTUV, yeeF, fliC, and fimA was performed by the method described previously (21). Gene disruption of puuP was performed as described previously (20). P1 transduction (22) was used to construct the multiple mutants or transfer the chromosomal deletion of a gene into another strain.…”

“…YeeF Is a Novel Putrescine Importer-YeeF is a homologue (63% identity) of PuuP, a putrescine importer that we have previously discovered (20). YeeF has recently been annotated as a putrescine importer in several databases.…”

“…PotE is responsible for both the excretion and uptake of putrescine (18). PuuP is the most recently discovered putrescine transporter and depends on proton motive force (19,20). In addition, two putative putrescine importers, YdcSTUV and YeeF, have been annotated by computer analysis.…”

Transforming a drug/H + antiporter into a polyamine importer by a single mutation

“…We assume that the inhibition of growth is due to the fact that, in rich medium, the putrescine utilization pathway is repressed (14) and the putrescine transported by the W63G mutant accumulates to high concentrations. However, putrescine can also be used as a carbon and nitrogen source by E. coli under conditions at which the putrescine utilization system is derepressed (such as minimal medium) (15). In addition to the intracellular enzymes required, the metabolism of putrescine needs the product of the PuuP gene, a putative putrescine transporter (15).…”

“…However, putrescine can also be used as a carbon and nitrogen source by E. coli under conditions at which the putrescine utilization system is derepressed (such as minimal medium) (15). In addition to the intracellular enzymes required, the metabolism of putrescine needs the product of the PuuP gene, a putative putrescine transporter (15). ΔpuuP cells transformed with either EmrE, W63G, the triple mutant, or with the pSN1 plasmid with no insert were capable of growing in a medium supplied with glucose as carbon and energy source and ammonium as a nitrogen source (Fig.…”