Proteomic Analysis to Investigate Regulatory Networks in Staphylococcus aureus - Bacterial Pathogenesis: Methods and Protocols - page 23

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Proteomic Analysis to Investigate Regulatory Networks
in Staphylococcus aureus

Susanne Engelmann and Michael Hecker

Summary
The analysis of the expression of virulence genes and the elucidation of metabolic
and regulatory pathways of Staphylococcus aureus provide us with important information
about the interaction between the pathogen and its host, mechanisms by which this
organism causes diseases, and the resistance to antibiotics. In order to investigate regulatory
networks of S. aureus , we analyze the cytoplasmic and extracellular proteome by using
two-dimensional (2D) gel analyses combined with matrix-assisted laser ionization-time-
of-flight mass spectrometry (MALDI-TOF MS). Gel-based proteomics is an extremely
valuable tool in microbial physiology that can, in combination with various visualization
and quantitation software packages, very rapidly provide comparative and quantitative
data for multi-sample comparison.

Key Words: 2D PAGE; protein expression profiling; DIGE labeling; [ 35 S]-l-
methionine pulse labeling; virulence gene expression; dual-channel imaging technique.

1. Introduction
The genome sequence information provides the basis for functional genomic
approaches such as DNA chip technologies and proteome analyses. The first
genome sequences of two Staphylococcus aureus strains, N315 and Mu50,
were published in 2001 (1) . To date, the complete genome sequences of
nine S. aureus strains have become available in the databases (www.tigr.org;
www.ncbi.nlm.nih.gov). The number of open reading frames varies from 2600
to 2700 between these strains. Despite this wealth of genome information, the
function of

∼ 1000 of the proteins encoded by these genes is still unknown.