Dataset Information

Functional mapping of an oligomeric autotransporter adhesin of Aggregatibacter actinomycetemcomitans.

ABSTRACT: Extracellular matrix protein adhesin A (EmaA) is a 202-kDa nonfimbrial adhesin, which mediates the adhesion of the oral pathogen Aggregatibacter actinomycetemcomitans to collagen. EmaA oligomers form surface antenna-like protrusions consisting of a long helical rod with an ellipsoidal ending. The functional analysis of in-frame emaA deletion mutants has located the collagen binding activity to the amino terminus of the protein corresponding to amino acids 70 to 386. The level of collagen binding of this deletion mutant was comparable to the emaA mutant strain. Transmission electron microscopy studies indicate that the first 330 amino acids of the mature protein form the ellipsoidal ending of the EmaA protrusions, where the activity resides. Amino acid substitution analysis within this sequence has identified a critical amino acid, which is essential for the formation of the ellipsoidal ending and for collagen binding activity.

SUBMITTER: Yu C

PROVIDER: S-EPMC2347400 | biostudies-literature | 2008 May

REPOSITORIES: biostudies-literature

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Functional mapping of an oligomeric autotransporter adhesin of Aggregatibacter actinomycetemcomitans.

Yu Chunxiao C Ruiz Teresa T Lenox Christopher C Mintz Keith P KP

Journal of bacteriology 20080229 9

Extracellular matrix protein adhesin A (EmaA) is a 202-kDa nonfimbrial adhesin, which mediates the adhesion of the oral pathogen Aggregatibacter actinomycetemcomitans to collagen. EmaA oligomers form surface antenna-like protrusions consisting of a long helical rod with an ellipsoidal ending. The functional analysis of in-frame emaA deletion mutants has located the collagen binding activity to the amino terminus of the protein corresponding to amino acids 70 to 386. The level of collagen binding ...[more]

PMID: 18310342

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Project description:The human oral pathobiont Aggregatibacter actinomycetemcomitans expresses multiple virulence factors, including the trimeric, extracellular matrix protein adhesin A (EmaA). The posttranslational modification of EmaA is proposed to be dependent on the sugars and enzymes associated with O-polysaccharide (O-PS) synthesis of the lipopolysaccharide (LPS). This modification is important for the structure and function of this adhesin. To determine if the composition of the sugars alters structure and/or function, the prototypic 202-kDa protein was expressed in a non-serotype b, emaA mutant strain. The transformed strain displayed EmaA adhesins similar in appearance to the prototypic adhesin as observed by two-dimensional (2D) electron microscopy of whole-mount negatively stained bacterial preparations. Biochemical analysis indicated that the protein monomers were posttranslationally modified. 3D electron tomographic reconstruction and structure analyses of the functional domain revealed three well-defined subdomains (SI, SII, and SIII) with a linker region between SII and SIII. Structural changes were observed in all three subdomains and the linker region of the adhesins synthesized compared with the known structure. These changes, however, did not affect the ability of the strain to bind collagen or form biofilms. The data suggest that changes in the composition of the glycan moiety alter the 3D structure of the molecule without negatively affecting the function(s) associated with this adhesin. IMPORTANCE The human oral pathogen A. actinomycetemcomitans is a causative agent of periodontal and several systemic diseases. EmaA is a trimeric autotransporter protein adhesin important for colonization by this pathobiont in vivo. This adhesin is modified with sugars associated with the O-polysaccharide (O-PS), and the modification is mediated using the enzymes involved in lipopolysaccharide (LPS) biosynthesis. The interaction with collagen is not mediated by the specific binding between the glycans and collagen but is attributed to changes in the final quaternary structure necessary to maintain an active adhesin. In this study, we have determined that the composition of the sugars utilized in the posttranslational modification of this adhesin is exchangeable without compromising functional activities.

Dataset Information

Functional mapping of an oligomeric autotransporter adhesin of Aggregatibacter actinomycetemcomitans.

Publications

Functional mapping of an oligomeric autotransporter adhesin of Aggregatibacter actinomycetemcomitans.

Similar Datasets

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