Gene regulation in Streptococcus pneumoniae - RePub - Erasmus ...

Interestingly, autolysis induced by LytA is important for the release of the major virulence
factor pneumolysin (36). The choline binding proteins CbpA, PspA, and PcpA have been
linked to adhesion to host cells and to colonization in mice (35, 52, 54).
Introduction
S. pneumoniae expresses over 42 lipoproteins, many of which play a role in virulence.
For example, PsaA, part of a manganese uptake system, and the oligopeptide permease
Ami/AliAB, are required for adhesion to host cells (1, 27). Interestingly, many of these
lipoproteins seem to have a dual role, i.e., uptake of ions and/or nutrients and modulation of
adhesion (directly or indirectly).
Examples of the non-classical surface-associated virulence factors with dual function
are α-enolase and glycerol-3-phosphate dehydrogenase, both involved in carbohydrate
metabolism (4, 18). In addition, PavA, pneumococcal adherence and virulence factor A, is a
fibronectin adhesin, which is an important factor involved in adherence, invasion and
modulation of meningal inflammation (21, 51). Together, these proteins form the most well
known virulence factors that pneumococcus has, and are important for adhesion to host cells
as well as bacterial survival within that host.
Expression of virulence factors
The expression kinetics of virulence factors during pathogenesis is largely unknown.
Most likely, gene regulatory pathways and signal transduction play an important role in
controlling the expression of these surface-exposed proteins. Consequently, expression
studies to map gene expression pathways are of high importance, and are expected to
contribute to the unraveling of the role of these proteins to the pathogenesis of pneumococcal
colonization and infection.
Gene regulation
During their life cycle, bacteria often encounter changes in their environment. For
pathogens in particular, this can be due to their migration to different sites in the human body.
Usually, pneumococci reside in the nasopharynx where they cause no harm, but in the lungs
they will cause serious infections. Clearly, adaptation to these changes is of utmost
importance for bacterial survival. This adaptation is achieved by sensing the intracellular
and/or extracellular environment and adjusting the transcription of genes to become most fit
for the new or upcoming situation. This transcriptional adjustment will lead to production of
new proteins, which will allow the pathogen to survive in its new environment.
Transcriptional regulatory proteins of diverse functions orchestrate changes in gene
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