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Review
. 2012 Mar 13:2:19.
doi: 10.3389/fcimb.2012.00019. eCollection 2012.

Nontypeable Haemophilus influenzae: the role of N-acetyl-5-neuraminic acid in biology

Michael A Apicella  1
Affiliations
Review

Nontypeable Haemophilus influenzae: the role of N-acetyl-5-neuraminic acid in biology

Michael A Apicella. Front Cell Infect Microbiol. .

Abstract

Nontypeable Haemophilus influenzae (NTHi) is an exclusive human pathogen, which has evolved a number of unique mechanisms to survive within the human environment. An important part of this is the ability of the organism to take up and incorporate sialic acid into its surface structures. This protects the organism against host adaptive and innate immune factor as well as serving as a mechanism for sustaining itself within biofilms. Recent evidence suggests that this also may be the source of the evolution of human antibodies to non-human sialic acid structures, which can lead to inflammation in the host. In very rare instances, evolution of antibodies to sialylated lipooligosaccharide (LOS) mimics of human antigens can result in autoimmune disease.

Keywords: Neu5Ac; nontypeable Haemophilus influenzae; sialic acid; sialyltransferases.

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Figures

Figure 1
Figure 1
A diagrammatic representation of the catabolic (■), uptake genes (□), and regulatory gene () of the two Sia operons in the H. influenzae genome are diagrammed in Figure 1. The intergenic region between the catabolic and uptake operons contains the binding sites for SiaR (solid Line) and Crp (dotted rectangle).
Figure 2
Figure 2
A composite model of Neu5Ac uptake, incorporation into LOS and catabolism into the Krebs cycle is shown. The different steps in the process is described in text.
Figure 3
Figure 3
A diagram showing the transmembrane loops of SiaT based on a hydrophobicity plot. The regions corresponding to DctQ and DctM are shown. Model based on prediction program at http://proteinformatics.charite.de/rhythm/index.php?site=helix.
See this image and copyright information in PMC

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