Identification and expression of a gene encoding for sialidase from Streptococcus oralis C104
Date
2001
DOI
Authors
Anmanee, Kopong
Version
OA Version
Citation
Abstract
S. oralis is a member of the normal oral flora and an opportunistic pathogen in
patient with attenuated host defensive mechanisms. The mechanisms by which S. oralis
causes this wide range of infections are as yet unclear, but the sialidase produced by this organism has been proposed as a contributing factor. The precise role of these enzymes is unknown, but it has been suggested that they act as generalized virulence determinants in that the release of sialic acid may expose cryptic carbohydrate binding sites for the
invading organisms and break down mucosal defensive barriers of the host. In order to
explore the role of this enzyme, a gene encoding for sialidase was cloned from S. oralis
Cl 04. A phagemid expressing sialidase activity containing a DNA insert of 4.7 kb was
completely sequenced. This insert contained the complete sialidase gene and two
incomplete ORFs. The sialidase gene is homologous to sialidases from a variety of
bacteria including S. pneumoniae, Erysipelothrix rhusiopathiae, and Clostridium
per:fingens. The sialidase gene contained four aspartate boxes (S-X-D-X-G-X-T-W) and
an anchor motif (L-P-N-T-G-S) at the C-terminus end. The anchor motif allows the
protein to cross the cell wall and anchors it to the cell surface. An incomplete ORF was
found 327 bp upstream of the sialidase ยท gene. It was homologous to an acetylxylan
esterase gene on a number of bacterial species including S. pneumoniae and Bacillus
halodurans. Another incomplete ORF was found 249 hp downstream of the sialidase
gene. It was homologous to the putative N-acetylmannosarnine-6-phosphate epimerase
from a number of bacterial species including S. pneumoniae nanE and Streptococcus pyogene. [TRUNCATED]
Description
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Thesis (M.Sc.D)--Boston University, Henry M. Goldman School of Dental Medicine, 2001 (Pediatric Dentistry).
Thesis (M.Sc.D)--Boston University, Henry M. Goldman School of Dental Medicine, 2001 (Pediatric Dentistry).
License
This work is protected by copyright. Downloading is restricted to the BU community. If you are the author of this work and would like to make it publicly available, please contact open-help@bu.edu.