Protein expression analysis ofChlamydia pneumoniae persistence by combined surface-enhanced laser desorption ionization time-of-flight mass spectrometry and two-dimensional polyacrylamide gel electrophoresis

Abstract

The aim of this study was to examine the protein expression profiles of persistent Chlamydia pneumoniae by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) and surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Although 2D PAGE is still the method of choice for separating and detecting components of complex protein mixtures, it has several distinct disadvantages; i.e., being laborintensive and having a bias toward proteins within the dynamic range of the gel condition. Hence, SELDI-TOF-MS technology was used to complement 2D PAGE. C. pneumoniae-infected HEp2 cells were treated with or without IFN-γ, and protein expression profiles were determined at 48 h postinfection (hpi). Unfractionated monolayers were also used for protein profiling by SELDI-TOF, using two different chip surface types: weak cation exchanger and hydrophobic surface. Under IFN-γ-induced persistence, C. pneumoniae expresses an altered protein expression profile. Twenty chlamydial proteins showed differential regulatory patterns