Characterization of Non-Covalent Complexes of Synthetic Peptides of RNA Polymerase Subunit σ70 From Chlamydia trachomatis with Protein G by nanoESI-MS

Abstract

To investigate the molecular mimicry between human ribosomal protein L7 with 70-kDa sigma factor (σ70) of the RNA polymerase of Chlamydia trachomatis, the complexes of synthetic σ70 peptides, σ(264–286), and σ(245–294), with protein G were investigated using nanoelectrospray ionization mass spectrometry (nanoESI-MS). The σ70 peptides were synthesized in the laboratory, purified by high performance liquid chromatography (HPLC), and identified by MS. The characteristics of the complexes of σ70 peptides with protein G were investigated under different conditions. The stability of the complexes decreased with the increase of declustering potential and acidity, whereas the sequence of σ70 peptides might have an obvious effect on the complex formation. In summary, the complexes of σ70 peptides with protein G are specific non-covalent binding. It is the first study regarding the binding of σ70 with protein G. This study could provide helpful information for the elucidation of binding mechanism of protein interaction and understanding of molecular mimicry.

Keywords:

• σ70 peptide
• mass spectrometry
• molecular mimicry
• non-covalent complex
• protein G
• stability