Biology Reference
In-Depth Information
Chapter 13
Proteomics of Porphyromonas gingivalis
Masae Kuboniwa, Erik L. Hendrickson, Qiangwei Xia, Tiansong Wang,
Hua Xie, Murray Hackett, and Richard J. Lamont
INTRODUCTION
Porphyromonas gingivalis is a periodontal pathogen that resides in a complex multi-
species microbial biofilm community known as dental plaque. Confocal laser scan-
ning microscopy (CLSM) showed that P. gingivalis can assemble into communities in
vitro with Streptococcus gordonii and Fusobacterium nucleatum , common constitu-
ents of dental plaque. Whole cell quantitative proteomics, along with mutant construc-
tion and analysis, were conducted to investigate how P. gingivalis adapts to this three
species community.
The 1,156 P. gingivalis proteins were detected qualitatively during comparison of
the three species model community with P. gingivalis incubated alone under the same
conditions. Integration of spectral counting and summed signal intensity analyses of
the dataset showed that 403 proteins were down-regulated and 89 proteins up-regulat-
ed. The proteomics results were inspected manually and an ontology analysis conduct-
ed using Database for Annotation, Visualization and Integrated Discovery (DAVID).
Signifi cant decreases were seen in proteins involved in cell shape and the formation of
the cell envelope, as well as thiamine, cobalamin, and pyrimidine synthesis and DNA
repair. An overall increase was seen in proteins involved in protein synthesis. The
hmuR, a TonB dependent outer membrane receptor, was up-regulated in the commu-
nity and a hmuR defi cient mutant was defi cient in three species community formation,
but was unimpaired in its ability to form mono- or dual-species biofi lms.
Collectively, these results indicate that P. gingivalis can assemble into a hetero-
typic community with F. nucleatum and S. gordonii , and that a community lifestyle
provides physiologic support for P. gingivalis . Proteins such as hmuR, that are up-
regulated, can be necessary for community structure.
The microbial communities that exist on oral surfaces are complex and dynamic
biofi lms that develop through temporally distinct patterns of microbial colonization [1,
2]. For example, initial colonizers of the salivary pellicle on the coronal tooth surface
are principally commensal oral streptococci such as S. gordonii and related species.
Establishment of these organisms facilitates the subsequent colonization of additional
gram-positives along with gram-negatives such as Fusobacterium nucleatum . As the
biofi lm extends below the gum line and becomes subgingival plaque, further matura-
tion is characterized by the colonization of more pathogenic gram-negative anaerobes
including Porphyromonas gingivalis [2-4]. While organisms such as P. gingivalis are
considered responsible for destruction of periodontal tissues, pathogenicity is only
 
 
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