Integrated regulatory responses of
 fimB
 to
 N
 -acetylneuraminic (sialic) acid and GlcNAc in
 Escherichia coli
 K-12

Sohanpal, Baljinder K.; El-Labany, Sammia; Lahooti, Maryam; Plumbridge, Jacqueline; Blomfield, Ian C.

doi:10.1073/pnas.0405821101

Cited by 101 publications

(144 citation statements)

References 61 publications

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“…fimB expression is regulated by Neu5Ac through the binding of the NanR regulator at a specific site in the fimB-yjhA intergenic region (Fig. 1A) (7,27). To verify whether NanR could also control yjhA expression, we measured expression of a yjhA-lacZ fusion in the absence and presence of Neu5Ac.…”

Section: Resultsmentioning

confidence: 99%

“…The start site corresponds to a Ϫ10 sequence of TATAAC and lies within the predicted NanR binding site containing two repeats of the GGTATA hexamer (10). NanR binds to this sequence (27). It can be noted that the nanC promoter is located in exactly the same position relative to the NanR binding site as the nanA promoter is within the NanR operator.…”

Section: Resultsmentioning

confidence: 99%

“…NanR and NagC are two regulators that control nanC expression by binding to or in the vicinity of its promoter. They also regulate fimB expression in a still unexplained way, since their binding sites are located more than 500 bp upstream of the fimB promoters (27). However, it is clear that they allow coordination of nanC and fimB expression, since NanR and NagC repress one and activate the other of these divergently arranged genes.…”

Section: Discussionmentioning

confidence: 99%

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Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

et al. 2005

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The Escherichia coli yjhA (renamed nanC) gene encodes a protein of the KdgM family of outer membranespecific channels. It is transcribed divergently from fimB, a gene involved in the site-specific inversion of the region controlling transcription of the fimbrial structural genes but is separated from it by one of the largest intergenic regions in E. coli. We show that nanC expression is induced by N-acetylneuraminic acid and modulated by N-acetylglucosamine. This regulation occurs via the NanR and NagC regulators, which also control fimB expression. nanC expression is also activated by the regulators cyclic AMP-catabolite activator protein, OmpR, and CpxR. When the NanC protein was reconstituted into liposomes, it formed channels with a conductance of 450 pS at positive potential and 300 to 400 pS at negative potential in 800 mM KCl. The channels had a weak anionic selectivity. In an ompR background, where the general porins OmpF and OmpC are absent, NanC is required for growth of E. coli on N-acetylneuraminic acid as the sole carbon source. All these results suggest that NanC is an N-acetylneuraminic acid outer membrane channel protein.Porins are proteins that form water-filled channels across the outer membrane of gram-negative bacteria. These channels allow the diffusion of hydrophilic molecules (Ͻ600 Da for the general porins OmpF and OmpC) into the periplasm with no particular substrate specificity. In Escherichia coli this family of proteins is represented by the trimeric porins OmpC, OmpF, and PhoE. Elucidation of the structure of these proteins showed that each monomeric barrel is formed by 16 ␤-strands (5). Other outer membrane channels catalyze the specific diffusion of a particular class of nutrient and thus allow the uptake of compounds that would diffuse too slowly through the general porins (15).The E. coli maltose-specific channel protein LamB and the sucrose channel protein ScrY are the best studied of this class of channel proteins. These proteins also form trimers, and each monomer consists of 18 transmembrane ␤-strands (24). A few other specific channels are known in E. coli: the aryl-␤-

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

et al. 2005

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“…1) (Corfield, 1992); however, other sialic acid-utilizing bacteria, such as the respiratory pathogen H. influenzae, lack genes for a sialidase yet are reliant on hostderived sialic acid (Bouchet et al, 2003). Presumably free sialic acid is made available to such pathogens by other, sialidase-expressing bacteria living in the same niche (Shakhnovich et al, 2002), or, as hypothesized by Sohanpal et al (2004Sohanpal et al ( , 2007, by host sialidases that are activated in the course of inflammation. The latter process is part of the normal recycling of sialic acid and there has been a recent suggestion that the host cells might use free sialic acid to help them cope with oxidative stress (Iijima et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Sialic acid utilization by bacterial pathogens

2007

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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.…”

Section: Introductionmentioning

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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Integrated regulatory responses of fimB to N -acetylneuraminic (sialic) acid and GlcNAc in Escherichia coli K-12

Cited by 101 publications

References 61 publications

Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

Function and Expression of an N -Acetylneuraminic Acid-Inducible Outer Membrane Channel in Escherichia coli

Sialic acid utilization by bacterial pathogens

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

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