Uropathogenic Escherichia coli CFT073 Is Adapted to Acetatogenic Growth but Does Not Require Acetate during Murine Urinary Tract Infection

Abstract

In vivo accumulation of D-serine by Escherichia coli CFT073 leads to elevated expression of PAP fimbriae and hemolysin by an unknown mechanism. Loss of D-serine catabolism by CFT073 leads to a competitive advantage during murine urinary tract infection (UTI), but loss of both D-and L-serine catabolism results in attenuation. Serine is the first amino acid to be consumed in closed tryptone broth cultures and precedes the production of acetyl phosphate, a high-energy molecule involved in intracellular signaling, and the eventual secretion of acetate. We propose that the colonization defect associated with the loss of serine catabolism is due to perturbations of acetate metabolism. CFT073 grows more rapidly on acetogenic substrates than does E. coli K-12 isolate MG1655. As shown by transcription microarray results, D-serine is catabolized into acetate via the phosphotransacetylase (pta) and acetate kinase (ackA) genes while downregulating expression of acetyl coenzyme A synthase (acs). CFT073 acs, which is unable to reclaim secreted acetate, colonized mouse bladders and kidneys in the murine model of UTI indistinguishably from the wild type. Both pta and ackA are involved in the maintenance of intracellular acetyl phosphate. CFT073 pta and ackA mutants were screened to investigate the role of acetyl phosphate in UTI pathogenesis. Both single mutants are at a competitive disadvantage relative to the wild type in the kidneys but normally colonize the bladder. CFT073 ackA pta was attenuated in both the bladder and the kidneys. Thus, we demonstrate that CFT073 is adapted to acetate metabolism as a result of requiring a proper cycling of the acetyl phosphate pathway for colonization of the upper urinary tract.Urinary tract infections (UTIs) place a significant burden on the United States healthcare system, costing upwards of $2.4 billion per year (28). The majority of women will experience a UTI in their lifetime, and every year there are approximately 6.8 million physician visits, 1.2 million emergency room visits, a quarter million hospitalizations, and thousands of deaths due to complications of UTIs, most often sepsis (10,18,28,47). Escherichia coli is the most commonly isolated causative agent of community-acquired UTIs (10).The transition from residence in the gastrointestinal tract, where uropathogenic Escherichia coli (UPEC) transiently resides, to the urinary tract represents a significant change in environment. While the gastrointestinal tract is densely populated with many different species of bacteria, the bladder is normally a sterile environment yet one that presents significant challenges to bacterial growth. In addition to the cleansing flow of urine, numerous innate and acquired immune factors challenge the growth of UPEC in the urinary tract. The host defense involves phagocytic attack, antimicrobial peptides, complement lytic and opsonizing factors, and reactive oxygen and nitrogen species. In addition, the urinary tract as reflected in urine is limited in nutrients common to the intestinal tract, esp...

Proteins differentially expressed by Shiga toxin-producing Escherichia coli strain M03 due to the biliar salt sodium deoxycholate

“…Acetyl phosphate also regulates the biosynthesis of some virulence factors such as pili and capsule (Wolfe et al, 2003;Wolfe, 2005), and plays a role in the pathogenesis of some bacteria. A pta mutant of the urinary E. coli CFT073 showed the inability to colonize the mouse kidney (Anfora et al, 2008). In Salmonella enterica Typhimurium a pta mutant was shown to be impaired in growth and attenuated in BALB/c mice (Kim et al, 2006).…”

Biochemical and Kinetic Characterization of the Eukaryotic Phosphotransacetylase Class IIa Enzyme from Phytophthora ramorum

“…Our knowledge of Pta and its physiological role has largely been limited to bacterial enzymes. The Pta-Ack pathway has been shown to be essential for growth and invasion in several pathogenic bacteria, including Vibrio cholerae (46), uropathogenic E. coli (47), S. enterica (48), and Listeria monocytogenes (49). A eukaryotic Pta has not previously been characterized, and the only report on the physiological role of a nonbacterial Pta is from the green alga Chlamydomonas (19).…”

A phosphotransacetylase from uropathogenic Staphylococcus saprophyticus: Characterization, kinetic analysis and its allosteric inhibition by α-ketoglutarate

“…Human urine also contains D-serine at concentrations between 3 and 115 mg/mL [40], which is toxic to some nonuropathogens but can be utilized or detoxified by uropathogenic E. coli CFT073. Welch and coworkers demonstrated that D-serine is preferentially consumed in tryptone broth by uropathogenic E. coli CFT073, and that the genes associated with acetate metabolism, including ackA and pta are upregulated, but acs is downregulated, following exposure to D-serine, which is catabolized into ammonia and pyruvate by serine deaminases [16]. Finally, the authors proposed that acetyl~P and acetyl-CoA whose intracellular levels are maintained by Pta and AckA play role in colonization of the urinary tract by CFT073 [16].…”

“…Welch and coworkers demonstrated that D-serine is preferentially consumed in tryptone broth by uropathogenic E. coli CFT073, and that the genes associated with acetate metabolism, including ackA and pta are upregulated, but acs is downregulated, following exposure to D-serine, which is catabolized into ammonia and pyruvate by serine deaminases [16]. Finally, the authors proposed that acetyl~P and acetyl-CoA whose intracellular levels are maintained by Pta and AckA play role in colonization of the urinary tract by CFT073 [16]. Sakinc et al showed that S. saprophyticus, but not the other Staphylococcus species that do not possess D-serine deaminase, tolerates a high concentration of D-serine [41].…”

“…The phosphotransacetylase activity also is of importance for virulence of some pathogenic bacteria. Welch and coworkers indicated that Pta-AckA pathway plays a role in colonization and pathogenesis of uropathogenic E. coli CFT073 during murine urinary tract infection (UTI), possibly by providing acetogenic products, acetyl~P and acetyl-CoA [16]. Acetyl~P has been shown to function as a global signal and hence to influence in vivo expression of almost 100 genes in many different microorganisms [for an excellent review see reference 1].…”