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

Abstract

Recently, many studies have reported that polyamines play a role in bacterial cell-to-cell signaling processes. The present study describes a novel putrescine importer required for induction of type 1 pili-driven surface motility. The surface motility of the Escherichia coli ⌬speAB ⌬speC ⌬potABCD strain, which cannot produce putrescine and cannot import spermidine from the medium, was induced by extracellular putrescine. Introduction of the gene deletions for known polyamine importers (⌬potE, ⌬potFGHI, and ⌬puuP) or a putative polyamine importer (⌬ydcSTUV) into the ⌬speAB ⌬speC ⌬potABCD strain did not affect putrescine-induced surface motility. The deletion of yeeF, an annotated putative putrescine importer, in the ⌬speAB ⌬speC ⌬potABCD ⌬ydcSTUV strain abolished surface motility in putrescine-supplemented medium. Complementation of yeeF by a plasmid vector restored surface motility. The surface motility observed in the present study was abolished by the deletion of fimA, suggesting that the surface motility is type 1 pili-driven. A transport assay using the yeeF ؉ or ⌬yeeF strains revealed that YeeF is a novel putrescine importer. The K m of YeeF (155 M) is 40 to 300 times higher than that of other importers reported previously. On the other hand, the V max of YeeF (9.3 nmol/min/mg) is comparable to that of PotABCD, PotFGHI, and PuuP. The low affinity of YeeF for putrescine may allow E. coli to sense the cell density depending on the concentration of extracellular putrescine.

Effects of Norspermidine and Spermidine on Biofilm Formation by Potentially Pathogenic Escherichia coli and Salmonella enterica Wild-Type Strains

“…They are present in all living cells. In bacteria, polyamines are involved in a variety of functions, including intercellular signaling, stress resistance, and RNA and protein synthesis, as well as motility and virulence (5)(6)(7)(8)(9)(10)(11)(12)(13). Some polyamines have also been shown to play an essential role in biofilm formation, i.e., putrescine in Yersinia pestis (14) and Escherichia coli (15), spermidine in Bacillus subtilis (16), and norspermidine in Vibrio cholerae (17).…”

Mechanism for Regulation of the Putrescine Utilization Pathway by the Transcription Factor PuuR in Escherichia coli K-12

“…Although the expressions of the regulatory mechanisms of E. coli putrescine importers have not been investigated under this experimental condition, E. coli has at least four such importers that may be used selectively, depending on growth conditions. Under the conditions used in our experiments, PlaP may function as the main putrescine importer (10). PlaP is a homologue (63% identity) of PuuP, although the affinity of PuuP for putrescine is much higher than that of PlaP.…”

“…PlaP was characterized as a low-affinity putrescine importer, and the ⌬plaP ⌬potABCD ⌬speAB ⌬speC E. coli strain did not exhibit surface motility on a plate containing putrescine, while the plaP ϩ ⌬potABCD ⌬speAB ⌬speC strain exhibited surface motility on the plate (10). The incorporation of 14 C-labeled putrescine was also significantly decreased in the ⌬plaP strain even when genes encoding other putrescine importers were not disrupted (10). Although the expressions of the regulatory mechanisms of E. coli putrescine importers have not been investigated under this experimental condition, E. coli has at least four such importers that may be used selectively, depending on growth conditions.…”

“…Recently, we reported that PlaP (previously named YeeF) was considered to function as a sensor for extracellular putrescine (10). PlaP was characterized as a low-affinity putrescine importer, and the ⌬plaP ⌬potABCD ⌬speAB ⌬speC E. coli strain did not exhibit surface motility on a plate containing putrescine, while the plaP ϩ ⌬potABCD ⌬speAB ⌬speC strain exhibited surface motility on the plate (10). The incorporation of 14 C-labeled putrescine was also significantly decreased in the ⌬plaP strain even when genes encoding other putrescine importers were not disrupted (10).…”

“…Of these reported three polyamine importers, only PuuP has been found to be essential for E. coli growth on minimal medium with putrescine as the sole carbon or nitrogen source (11). PlaP (previously named YeeF) was recently discovered and shows a low affinity for putrescine but is essential for the surface motility response induced by extracellular putrescine (10).…”