GlcNAc-6P Levels Modulate the Expression of Curli Fibers by<i>Escherichia coli</i>

Barnhart, Michelle M.; Lynem, Jaclyn; Chapman, Matthew R.

doi:10.1128/jb.00234-06

Cited by 52 publications

(57 citation statements)

References 56 publications

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“…The glucosamine-6-phosphate isomerase NagB is part of the nag operon, whose genes are involved in the metabolism of N-acetylglucosamine 6-phosphate (GlcNAc6P), an important precursor of peptidoglycan and LPS synthesis. In E. coli, increases in the intracellular level of this precursor lead to the upregulation of the nag operon (Barnhart et al, 2006) and downregulation of curli and type 1 pili (Barnhart et al, 2006;Sohanpal et al, 2004), both known to be involved in biofilm formation (Kikuchi et al, 2005;Pratt & Kolter, 1998). Curli have been shown to assist in uroepithelial cell attachment in E. coli (Kikuchi et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

The high-affinity phosphate transporter Pst in Proteus mirabilis HI4320 and its importance in biofilm formation

et al. 2009

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Proteus mirabilis causes urinary tract infections (UTIs) in individuals requiring long-term indwelling catheterization. The pathogenesis of this uropathogen is mediated by a number of virulence factors and the formation of crystalline biofilms. In addition, micro-organisms have evolved complex systems for the acquisition of nutrients, including the phosphate-specific transport system, which has been shown to be important in biofilm formation and pathogenesis. A functional Pst system is important during UTIs caused by P. mirabilis HI4320, since transposon mutants in the PstS periplasmic binding protein and the PstA permease protein were attenuated in the CBA mouse model of UTI. These mutants displayed a defect in biofilm formation when grown in human urine. This study focuses on a comparison of the proteomes during biofilm and planktonic growth in phosphate-rich medium and human urine, and microscopic investigations of biofilms formed by the pst mutants. Our data suggest that (i) the Dpst mutants, and particularly the DpstS mutant, are defective in biofilm formation, and (ii) the proteomes of these mutants differ significantly from that of the wild-type. Therefore, since the Pst system of P. mirabilis HI4320 negatively regulates biofilm formation, this system is important for the pathogenesis of these organisms during complicated UTIs. INTRODUCTIONProteus mirabilis -a member of the family Enterobacteriaceae -is the most common aetiological agent responsible for complicated urinary tract infections (UTIs) (Mobley, 1996). Subpopulations at higher risk for infection by this pathogen include those with long-term indwelling catheterization as well as those with structural and functional abnormalities within the urinary tract (Mobley, 1996). Clinical syndromes associated with P. mirabilis include cystitis and pyelonephritis, with possible complications from stone formation and bacteraemia (Mobley, 1996). These micro-organisms survive in the urinary tract by virtue of their production of a battery of virulence factors, including urease, flagella, fimbriae, haemolysin and IgA protease (Belas, 1996;Mobley et al., 1994;Musher et al., 1975;Peerbooms et al., 1984; Walker et al., 1999), and formation of crystalline biofilm on indwelling catheters (Stickler et al., 1993).Biofilm formation -one of the most important mechanisms of pathogenicity of this micro-organism in the urinary tract -may be defined as a community of surface-attached bacteria encased in an extracellular matrix consisting of secreted carbohydrates, proteins and DNA. Indeed, biofilms have been associated with the virulence of a number of pathogens (Castelli et al., 2006). Organisms in these communities display phenotypic differences from planktonic cells, including a slower rate of growth and increased resistance to antibiotics (Lewis, 2001;Stoodley et al., 2002). P. mirabilis biofilms in urine are unique in that the extracellular polysaccharide matrix is enmeshed with struvite and carbonate apatite crystals (Jones et al., 2006).Abbreviations: CLSM, confocal ...

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Section: Discussionmentioning

confidence: 99%

The high-affinity phosphate transporter Pst in Proteus mirabilis HI4320 and its importance in biofilm formation

et al. 2009

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“…One aspect of GlcNAc function is to mediate cellular signaling. In bacteria, GlcNAc induces components that are important for colonization of human hosts, including fimbrins that mediate adhesion to host cells (Sohanpal et al, 2004), multidrug exporter genes (Hirakawa et al, 2006) and Curli fibers that promote biofilm formation (Barnhart et al, 2006). In mammals, GlcNAc is a key sensor of nutrient status that is involved in insulin signaling, cell cycle control, and other essential processes.…”

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confidence: 99%

Identification of anN-Acetylglucosamine Transporter That Mediates Hyphal Induction inCandida albicans

Álvarez

Konopka

2007

MBoC

126

171

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The sugar N-acetylglucosamine (GlcNAc) plays an important role in nutrient sensing and cellular regulation in a wide range of organisms from bacteria to humans. In the fungal pathogen Candida albicans, GlcNAc induces a morphological transition from budding to hyphal growth. Proteomic comparison of plasma membrane proteins from buds and from hyphae induced by GlcNAc identified a novel hyphal protein (Ngt1) with similarity to the major facilitator superfamily of transporters. An Ngt1-GFP fusion was detected in the plasma membrane after induction with GlcNAc, but not other related sugars. Ngt1-GFP was also induced by macrophage phagocytosis, suggesting a role for the GlcNAc response in signaling entry into phagolysosomes. NGT1 is needed for efficient GlcNAc uptake and for the ability to induce hyphae at low GlcNAc concentrations. High concentrations of GlcNAc could bypass the need for NGT1 to induce hyphae, indicating that elevated intracellular levels of GlcNAc induce hyphal formation. Expression of NGT1 in Saccharomyces cerevisiae promoted GlcNAc uptake, indicating that Ngt1 acts directly as a GlcNAc transporter. Transport mediated by Ngt1 was specific, as other sugars could not compete for the uptake of GlcNAc. Thus, Ngt1 represents the first eukaryotic GlcNAc transporter to be discovered. The presence of NGT1 homologues in the genome sequences of a wide range of eukaryotes from yeast to mammals suggests that they may also function in the cellular processes regulated by GlcNAc, including those that underlie important diseases such as cancer and diabetes. INTRODUCTIONN-acetylglucosamine (GlcNAc) is an amino sugar that carries out important roles in a broad range of cells from bacteria to humans. One aspect of GlcNAc function is to mediate cellular signaling. In bacteria, GlcNAc induces components that are important for colonization of human hosts, including fimbrins that mediate adhesion to host cells (Sohanpal et al., 2004), multidrug exporter genes (Hirakawa et al., 2006) and Curli fibers that promote biofilm formation (Barnhart et al., 2006). In mammals, GlcNAc is a key sensor of nutrient status that is involved in insulin signaling, cell cycle control, and other essential processes. Nutritional effects that lead to increased GlcNAc levels result in its conversion to UDP-GlcNAc and subsequent attachment to proteins on serine or threonine residues in a dynamic manner that is analogous to modification of proteins by phosphorylation (Slawson and Hart, 2003;Zachara and Hart, 2006). In fact, the interplay between O-GlcNAc modification and phosphorylation of proteins regulates many critical transcription factors, such as c-myc and p53 (Chou and Hart, 2001;Yang et al., 2006). O-GlcNAc modification also regulates other processes including proteosome function (Zachara and Hart, 2004). In addition to these regulatory roles, GlcNAc contributes to the N-linked glycosylation, glycophosphatidylinositol (GPI) anchor addition to proteins and is polymerized into chitin, which forms part of the fungal cell wall and the exoskele...

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“…Additionally, GlcNAc is widely used as a signaling molecule. For example, bacterial cells respond to extracellular GlcNAc by altering the production of CURLI fibers that function in biofilm formation (1), and some yeast species are induced by GlcNAc to switch from budding to a filamentous hyphal morphology that promotes invasive growth (2,3). Animal cells respond to increased GlcNAc by promoting the post-translational attachment of GlcNAc to intracellular proteins, including the transcription factors c-Myc, p53, and NF-B that play key roles in cellular regulation (4).…”

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N-Acetylglucosamine (GlcNAc) Induction of Hyphal Morphogenesis and Transcriptional Responses in Candida albicans Are Not Dependent on Its Metabolism

Naseem¹,

Gunasekera²,

Araya

et al. 2011

Journal of Biological Chemistry

118

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N-Acetylglucosamine (GlcNAc) stimulates important signaling pathways in a wide range of organisms. In the human fungal pathogen Candida albicans, GlcNAc stimulates hyphal cell morphogenesis, virulence genes, and the genes needed to catabolize GlcNAc. Previous studies on the GlcNAc transporter (NGT1) indicated that GlcNAc has to be internalized to induce signaling. Therefore, the role of GlcNAc catabolism was examined by deleting the genes required to phosphorylate, deacetylate, and deaminate GlcNAc to convert it to fructose-6-PO 4 (HXK1, NAG1, and DAC1). As expected, the mutants failed to utilize GlcNAc. Surprisingly, GlcNAc inhibited the growth of the nag1⌬ and dac1⌬ mutants in the presence of other sugars, suggesting that excess GlcNAc-6-PO 4 is deleterious. Interestingly, both hxk1⌬ and an hxk1⌬ nag1⌬ dac1⌬ triple mutant could be efficiently stimulated by GlcNAc to form hyphae. These mutants could also be stimulated to express GlcNAcregulated genes. Because GlcNAc must be phosphorylated by Hxk1 to be catabolized, and also for it to enter the anabolic pathways that form chitin, N-linked glycosylation, and glycosylphosphatidylinositol anchors, the mutant phenotypes indicate that GlcNAc metabolism is not needed to induce signaling in C. albicans. Thus, these studies in C. albicans reveal a novel role for GlcNAc in cell signaling that may also regulate critical pathways in other organisms.

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GlcNAc-6P Levels Modulate the Expression of Curli Fibers byEscherichia coli

Cited by 52 publications

References 56 publications

The high-affinity phosphate transporter Pst in Proteus mirabilis HI4320 and its importance in biofilm formation

The high-affinity phosphate transporter Pst in Proteus mirabilis HI4320 and its importance in biofilm formation

Identification of anN-Acetylglucosamine Transporter That Mediates Hyphal Induction inCandida albicans

N-Acetylglucosamine (GlcNAc) Induction of Hyphal Morphogenesis and Transcriptional Responses in Candida albicans Are Not Dependent on Its Metabolism

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