Osmoregulatory transporter ProP influences colonization of the urinary tract by Escherichia coli

Abstract

Osmoregulatory transporters Prop and ProU mediate the use of betaines as osmoprotectants by Escherichia coli. Glycine betaine and proline betaine are present in mammalian urines. Betaine uptake may therefore facilitate the growth of Em coli in the urinary tract, an environment of fluctuating osmolality. Prop transporter activity was approximately threefold higher in a pyelonephritis isolate, E. coli HU734, than in E. coli K-12. The growth rate of E. coli HU734 in aerated minimal salts medium was reduced twofold by 0 2 M NaCl in the absence and by 055 M NaCl in the presence of glycine betaine.Maximal growth rate stimulation was achieved when glycine betaine was added a t a concentration as low as 25 pM. Deletion of the prop locus impaired the growth rate of E. coli HU734 in human urine but not in minimal medium supplemented with NaCl (04 M), with or without glycine betaine (0-1 mM). The expression of pyelonephritis-associated (P) pili was reduced when E. coli HU734 was cultured in a rich culture medium (LB) of elevated salinity. The prop lesion had no influence on P pilus expression in witm or on the recovery of bacteria from the kidneys of inoculated mice. However, it did reduce their recovery from the bladders of inoculated mice 100-fold. These data provide the first direct evidence that osmoprotective betaine accumulation and transporter Prop are pertinent to both growth in human urine and colonization of the murine urinary tract by uropathogenic E. coli.

The osmotic stress response and virulence in pyelonephritis isolates of Escherichia coli: contributions of RpoS, ProP, ProU and other systems The GenBank accession numbers for the DNA sequences of the rpoS loci in E. coli strains HU734 and CFT073 are AF275947 and AF270497, respectively.

“…MOPS medium was supplemented, unless otherwise stated, with -glucose (0n2%, w\v) as carbon source, NH % Cl (9n5 mM) as nitrogen source, amino acids (50 µg ml − ") to meet auxotrophic requirements and thiamine HCl (1 µg ml − "). The collection and preparation of human urine, measurements of bacterial growth in minimal medium and in urine were as described previously (Culham et al, 1998). The osmolalities of culture media and human urine specimens were determined with a vapour pressure osmometer (Wescor).…”

“…Neither osmotolerance (Kunin et al, 1992 ;Peddie et al, 1996) nor the occurrence of betaine transporters ProP and ProU (Culham et al, 1994) is correlated with isolation from the urinary tract for E. coli. Nevertheless, the growth rate of E. coli HU734, an acute pyelonephritis isolate, in high-osmolality human urine was reduced by deletion of the gene encoding osmoregulatory betaine transporter ProP (Culham et al, 1998).…”

“…Despite its high urea content, fluctuating osmolality and pH, urine supports rapid and extensive growth of E. coli, at least under aerobic conditions (Culham et al, 1998 ;Gordon & Riley, 1992). Upon demonstrating that GB and proline betaine conferred osmoprotective activity on human urine, Chambers & Kunin (1987) inferred that osmoregulatory betaine uptake may promote growth in urine and colonization of the human urinary tract by E. coli .…”

“…Booth & Louis, 1999 ;Wood, 1999). Evidence regarding the existence of those and other systems in pyelonephritis isolates HU734 and CFT073 has been published (Culham et al, 1994(Culham et al, , 1998 and is provided herein. Accumulation of trehalose by E. coli HU734 is very limited due to an RpoS defect (see text and Fig.…”

Effect of Osmolarity on Virulence of Uropathogenic Pseudomonas Aeruginosa

“…This was true for both planktonic and biofilm cells of all the strains of P. aeruginosa. Culham et al [35] highlighted that in addition to directly influencing bacterial growth in the urinary tract, osmoregulatory mechanisms may indirectly influence urinary tract infection by affecting the expression of virulence determinants. Later in 2001, these workers reported presence of additional osmoregulatory systems in E. coli K-12, which may facilitate growth of pyelonephritic isolates in human urine and also assist in colonization of mammalian urinary tract.…”