Glycosylation of the Collagen Adhesin EmaA of<i>Aggregatibacter actinomycetemcomitans</i>Is Dependent upon the Lipopolysaccharide Biosynthetic Pathway

Tang, Guoping; Mintz, Keith P.

doi:10.1128/jb.01453-09

Cited by 45 publications

(116 citation statements)

References 59 publications

(63 reference statements)

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“…EmaA is modified with the O PS moiety of LPS containing fucose, rhamnose, and GalNAc (437,438). Strikingly, the O PS is attached in the periplasm to the protein via the activity of the O-antigen ligase WaaL (437,439). The glycan was proven to be crucial for collagen binding and the protection of EmaA against proteolytic degradation (439).…”

Section: Protein Glycosylationmentioning

confidence: 99%

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The Sweet Tooth of Bacteria: Common Themes in Bacterial Glycoconjugates

Tytgat

Lebeer

2014

Microbiol Mol Biol Rev

128

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SUMMARY Humans have been increasingly recognized as being superorganisms, living in close contact with a microbiota on all their mucosal surfaces. However, most studies on the human microbiota have focused on gaining comprehensive insights into the composition of the microbiota under different health conditions (e.g., enterotypes), while there is also a need for detailed knowledge of the different molecules that mediate interactions with the host. Glycoconjugates are an interesting class of molecules for detailed studies, as they form a strain-specific barcode on the surface of bacteria, mediating specific interactions with the host. Strikingly, most glycoconjugates are synthesized by similar biosynthesis mechanisms. Bacteria can produce their major glycoconjugates by using a sequential or an en bloc mechanism, with both mechanistic options coexisting in many species for different macromolecules. In this review, these common themes are conceptualized and illustrated for all major classes of known bacterial glycoconjugates, with a special focus on the rather recently emergent field of glycosylated proteins. We describe the biosynthesis and importance of glycoconjugates in both pathogenic and beneficial bacteria and in both Gram-positive and -negative organisms. The focus lies on microorganisms important for human physiology. In addition, the potential for a better knowledge of bacterial glycoconjugates in the emerging field of glycoengineering and other perspectives is discussed.

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Section: Protein Glycosylationmentioning

confidence: 99%

“…This protein trimerizes to form antenna-like structures that can bind collagen. EmaA is modified with the O PS moiety of LPS containing fucose, rhamnose, and GalNAc (437,438). Strikingly, the O PS is attached in the periplasm to the protein via the activity of the O-antigen ligase WaaL (437,439).…”

Section: Protein Glycosylationmentioning

confidence: 99%

The Sweet Tooth of Bacteria: Common Themes in Bacterial Glycoconjugates

Tytgat

Lebeer

2014

Microbiol Mol Biol Rev

128

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“…EmaA is structurally distinct from the other two auto-transporters, with coiled-coil, glycosylated monomers trimerizing to form antenna-like protrusions on the bacterial cell surface. These comprise a stalk of approximately 150 nm that terminates in an ellipsoidal cap, within which the collagenbinding domain is located (Ruiz et al, 2006;Yu et al, 2008;Tang and Mintz, 2010). Specific amino acid residues within the stalk have been shown to introduce bends within the structure, conferring flexibility to ensure optimal adhesion to collagen (Yu et al, 2009).…”

Section: Auto-transporter Adhesins -Emaamentioning

confidence: 99%

Stick to Your Gums

2011

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Studies on the adherence properties of oral bacteria have been a major focus in microbiology research for several decades. The ability of bacteria to adhere to the variety of surfaces present in the oral cavity, and to become integrated within the resident microbial communities, confers growth and survival properties. Molecular analyses have revealed several families of Grampositive bacterial surface proteins, including serine-rich repeat, antigen I/II, and pilus families, that mediate adherence to a variety of salivary and oral bacterial receptors. In Gram-negative bacteria, pili, auto-transporters, and extracellular matrix-binding proteins provide components for host tissue recognition and building of complex microbial communities. Future studies will reveal in greater detail the binding pockets for these adhesin families and their receptors. This information will be crucial for the development of new inhibitors or vaccines that target the functional regions of bacterial proteins that are involved in colonization and pathogenesis.

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“…EmaAs are hypothesized to be glycosylated by a novel post-translational mechanism. This mechanism shares the same enzyme that ligates the O-polysaccharide (O-PS) sugars to the lipopolysaccharide [3]. Seven different serotypes associated with A. actinomycetemcomitans have been identified based on different O-PS sugars.…”

mentioning

confidence: 99%

“…The sugar-moiety chimera EmaA (a-EmaA) expressed in this strain was compared to the wild type b-EmaA expressed in a serotype b strain. The collagen binding activity of the a-emaA -/b-emaA + strain was determined using an enzymelinked absorbent assay (ELISA) [3,4]. Electron microscopy was performed on deep negatively stained whole-mount bacterial preparations [5].…”

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confidence: 99%

Structure Analysis of a Sugar-moiety Chimera of EmaA, a Collagen Adhesin of a Gram-negative Bacterial Pathogen

et al. 2017

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The gram-negative non-motile bacterium, Aggregatibacter actinomycetemcomitans is an oropharyngeal colonizer. A. actinomycetemcomitans causes aggressive periodontitis and systemic infections, including endocarditis and pneumonia. Multiple virulence factors are involved in the infective process, and EmaA (extracellular matrix adhesin A) is one of the important virulence determinants in the early stage of infection. EmaA is a trimeric autotransporter adhesin, composed of three 202 kDa monomers, and forms antenna-like appendages extending more than 150 nm from the bacterial surface [1]. The functional Nterminus, encompasses approximately 30 nm from the distal end, and comprises three subdomains (SI, SII and SIII), with a linker region between subdomains SII and SIII [2]. EmaAs are hypothesized to be glycosylated by a novel post-translational mechanism. This mechanism shares the same enzyme that ligates the O-polysaccharide (O-PS) sugars to the lipopolysaccharide [3]. Seven different serotypes associated with A. actinomycetemcomitans have been identified based on different O-PS sugars. Accordingly, the sugars present in the EmaA of each serotype are different. The O-PS of serotype a strains is composed of repeated disaccharide units of talose, while the O-PS of serotype b strains consists of repeated rhamnose-fucose-acetylgalactosamine trisaccharides. Glycosylation, as well as the primary sequence, are important for the function and stability of the EmaA adhesin [4]. Therefore, 3D structures of EmaA (the serotype b sequence) modified with the sugars from a serotype a strain (talose), a sugar-moiety chimera, were reconstructed for better understanding the functional role of glycosylation in this adhesin.Electron tomography analysis was performed to resolve the 3D structure of a sugar-moiety chimera of EmaA. A plasmid carrying the full-length serotype b emaA sequence was transformed into a serotype a emaA -mutant strain (a-emaA -) to generate a new strain a-emaA -/b-emaA + . The sugar-moiety chimera EmaA (a-EmaA) expressed in this strain was compared to the wild type b-EmaA expressed in a serotype b strain. The collagen binding activity of the a-emaA -/b-emaA + strain was determined using an enzymelinked absorbent assay (ELISA) [3,4]. Electron microscopy was performed on deep negatively stained whole-mount bacterial preparations [5]. Bacteria were grown in broth and collected by centrifugation at ×3,000 g for 1 min at 4°C, A 5 µl aliquot of bacterial suspension was placed onto carbon-coated grids pretreated with low molecular weight polylysine (~3 kDa) and colloidal gold, and negatively stained with Nano W (Nanoprobes, NY). Grids were imaged at 100 kV with a Tecnai 12 electron microscope (FEI, OR) Tomographic tilt series were acquired within a ±64° angular range at 2° angular intervals. Tomographic reconstructions of the whole imaged area were calculated using IMOD. For each selected EmaA from the tomogram, a tilt series of subprojections was extracted and subvolumes were calculated with the long-axis of the adhesin ap...

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Glycosylation of the Collagen Adhesin EmaA ofAggregatibacter actinomycetemcomitansIs Dependent upon the Lipopolysaccharide Biosynthetic Pathway

Cited by 45 publications

References 59 publications

The Sweet Tooth of Bacteria: Common Themes in Bacterial Glycoconjugates

The Sweet Tooth of Bacteria: Common Themes in Bacterial Glycoconjugates

Stick to Your Gums

Structure Analysis of a Sugar-moiety Chimera of EmaA, a Collagen Adhesin of a Gram-negative Bacterial Pathogen

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