Type 1 fimbriae mutants of <i>Escherichia coli</i> K12: characterization of recognized afimbriate strains and construction of new <i>fim</i> deletion mutants

Blomfield, Ian C.; McClain, Mark S.; Eisenstein, Barry I.

doi:10.1111/j.1365-2958.1991.tb00790.x

Cited by 163 publications

(84 citation statements)

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“…Type 1 pili mediate binding to mannosylated glycoproteins present in the bladder and are associated with cystitis (18,31). P pili are critical for binding to Gal␣ (1)(2)(3)(4)Gal moieties present in the kidney and are associated with pyelonephritis (5,31). These pili are composite structures built from multiple pilus subunits (6).…”

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confidence: 99%

The Usher N Terminus Is the Initial Targeting Site for Chaperone-Subunit Complexes and Participates in Subsequent Pilus Biogenesis Events

et al. 2004

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Pilus biogenesis on the surface of uropathogenic Escherichia coli requires the chaperone/usher pathway, a terminal branch of the general secretory pathway. In this pathway, periplasmic chaperone-subunit complexes target an outer membrane (OM) usher for subunit assembly into pili and secretion to the cell surface. The molecular mechanisms of protein secretion across the OM are not well understood. Mutagenesis of the P pilus usher PapC and the type 1 pilus usher FimD was undertaken to elucidate the initial stages of pilus biogenesis at the OM. Deletion of residues 2 to 11 of the mature PapC N terminus abolished the targeting of the usher by chaperone-subunit complexes and rendered PapC nonfunctional for pilus biogenesis. Similarly, an intact FimD N terminus was required for chaperone-subunit binding and pilus biogenesis. Analysis of PapC-FimD chimeras and N-terminal fragments of PapC localized the chaperone-subunit targeting domain to the first 124 residues of PapC. Single alanine substitution mutations were made in this domain that blocked pilus biogenesis but did not affect targeting of chaperone-subunit complexes. Thus, the usher N terminus does not function simply as a static binding site for chaperone-subunit complexes but also participates in subsequent pilus assembly events.

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The Usher N Terminus Is the Initial Targeting Site for Chaperone-Subunit Complexes and Participates in Subsequent Pilus Biogenesis Events

et al. 2004

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“…WAM2880 is a derivative of CFT073 that is deleted for lacZYA (42). E. coli AAEC185 was used as a host for construction of recombinant plasmids (6). Other strains constructed for this study are described below, and a summary of all strains used can be seen in Table 1.…”

Section: Methodsmentioning

confidence: 99%

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

et al. 2008

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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...

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“…Both of these strains express filamentous adhesive organelles called type 1 pili (Blomfield et al, 1991;Langermann et al, 1997). These fibers mediate both bacterial adherence to and invasion of host epithelial cells, and they are major virulence factors encoded by virtually all UPEC isolates (Martinez et al, 2000).…”

Section: Upec Stimulates Dephosphorylation Of Akt In Bladder Epithelimentioning

confidence: 99%

Inactivation of Host Akt/Protein Kinase B Signaling by Bacterial Pore-forming Toxins

Wiles

Dhakal

Eto

et al. 2008

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102

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Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections (UTIs), and they have the capacity to induce the death and exfoliation of target uroepithelial cells. This process can be facilitated by the pore-forming toxin ␣-hemolysin (HlyA), which is expressed and secreted by many UPEC isolates. Here, we demonstrate that HlyA can potently inhibit activation of Akt (protein kinase B), a key regulator of host cell survival, inflammatory responses, proliferation, and metabolism. HlyA ablates Akt activation via an extracellular calcium-dependent, potassium-independent process requiring HlyA insertion into the host plasma membrane and subsequent pore formation. Inhibitor studies indicate that Akt inactivation by HlyA involves aberrant stimulation of host protein phosphatases. We found that two other bacterial pore-forming toxins (aerolysin from Aeromonas species and ␣-toxin from Staphylococcus aureus) can also markedly attenuate Akt activation in a dose-dependent manner. These data suggest a novel mechanism by which sublytic concentrations of HlyA and other pore-forming toxins can modulate host cell survival and inflammatory pathways during the course of a bacterial infection. INTRODUCTIONStrains of uropathogenic Escherichia coli (UPEC) are the leading cause of urinary tract infections (UTIs), which currently rank among the most common of infectious diseases worldwide (Foxman, 2003;Marrs et al., 2005). During the course of an infection, UPEC can stimulate a number of antimicrobial, proinflammatory, prodifferentiation, proliferation, and host cell death pathways (Mulvey, 2002;Mysorekar et al., 2002). In some cases, UPEC can reportedly modulate these signaling events, causing attenuation of host inflammatory responses and potentiating host apoptotic cascades (Klumpp et al., 2001(Klumpp et al., , 2006Hunstad et al., 2005;Billips et al., 2007). These phenomena have been linked in part to the suppression of nuclear factor-B (NF B) activation and downstream signaling by unknown factors associated with UPEC (Klumpp et al., 2001;Hunstad et al., 2005). By hindering host cytokine expression and ensuing inflammatory responses, UPEC may be better able to establish itself and multiply within the cells and tissues of the urinary tract. At the same time, UPEC-induced death of bladder and renal epithelial cells can compromise mucosal barriers, and it may thereby facilitate bacterial dissemination and persistence within the urinary tract (Mulvey et al., 1998Chen et al., 2003a;Bower et al., 2005;Eto et al., 2006;Mansson et al., 2007b).A key regulator of host cell survival pathways is Akt (also known as protein kinase B, PKB; for recent reviews, see Fayard et al., 2005;Song et al., 2005;Manning and Cantley, 2007). This serine/threonine kinase is able to inhibit apoptosis, and it can help control cell cycle and metabolic pathways, endocytosis and vesicular trafficking, and host inflammatory responses, including the activation of NF B. Akt is activated downstream of phosphoinositide 3-kinase (PI3-kinase), which it...

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Type 1 fimbriae mutants of Escherichia coli K12: characterization of recognized afimbriate strains and construction of new fim deletion mutants

Cited by 163 publications

References 31 publications

The Usher N Terminus Is the Initial Targeting Site for Chaperone-Subunit Complexes and Participates in Subsequent Pilus Biogenesis Events

The Usher N Terminus Is the Initial Targeting Site for Chaperone-Subunit Complexes and Participates in Subsequent Pilus Biogenesis Events

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

Inactivation of Host Akt/Protein Kinase B Signaling by Bacterial Pore-forming Toxins

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