Activation of the alternative sigma factor SigB of Staphylococcus aureus following internalization by epithelial cells - an in vivo proteomics perspective.
Staphylococcus aureus is a versatile pathogen that can be a commensal but also cause a wide range of different infections. This broad disease spectrum is a reflection of the complex regulation of a large collection of virulence factors that together with metabolic fitness allow adaptation to different niches. The alternative sigma factor SigB is one of the global regulators mediating this adaptation. However, even if SigB contributes to expression of many virulence factors its importance for successful infection greatly varies with the strain and the infection setting analyzed. We have recently established a proteomics workflow that combines high efficiency cell sorting with sensitive mass spectrometry and allows monitoring of global proteome adaptations with roughly one million bacterial cells. Thus, we can now approach the adaptation of pathogens to the intracellular milieu. In the current study this proteomics workflow was used in conjunction with qRT-PCR and confocal fluorescence microscopy to comparatively analyze the adaptation of the S. aureus wild type strain HG001 and its isogenic sigB mutant to the intracellular milieu of human S9 bronchial epithelial cells. The study revealed fast and transient activation of SigB following internalization by human host cells and the requirement of SigB for intracellular growth. Loss of SigB triggered proteome changes reflecting the different residual growth rates of wild type and sigB mutant, respectively, the resistance to methicillin, adaptation to oxidative stress and protein quality control mechanisms.
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany.
Henrike
H
Pförtner
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany.
Marc S
MS
Burian
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, ZIK-FunGene Junior Research Group "Applied Proteomics", Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany.
Stephan
S
Michalik
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, ZIK-FunGene Junior Research Group "Applied Proteomics", Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany.
Maren
M
Depke
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, ZIK-FunGene Junior Research Group "Applied Proteomics", Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany.
Petra
P
Hildebrandt
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany.
Vishnu M
VM
Dhople
Ernst-Moritz-Arndt-University Greifswald, Institute for Microbiology, Friedrich-Ludwig-Jahn-Straße 15, 17487 Greifswald, Germany.
Jan
J
Pané-Farré
Ernst-Moritz-Arndt-University Greifswald, Institute for Microbiology, Friedrich-Ludwig-Jahn-Straße 15, 17487 Greifswald, Germany.
Michael
M
Hecker
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, ZIK-FunGene Junior Research Group "Applied Proteomics", Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany.
Frank
F
Schmidt
University Medicine Greifswald, Interfaculty Institute of Genetics and Functional Genomics, Friedrich-Ludwig-Jahn-Straße 15a, 17475 Greifswald, Germany. Electronic address: voelker@uni-greifswald.de.
Uwe
U
Völker
D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D002460:Cell Line; D004705:Endocytosis; D004847:Epithelial Cells / Q000382:microbiology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D054884:Host-Pathogen Interactions; D006801:Humans; D018613:Microscopy, Confocal; D020543:Proteome / Q000032:analysis*; D060888:Real-Time Polymerase Chain Reaction; D012808:Sigma Factor / Q000096:biosynthesis* / Q000235:genetics; D013211:Staphylococcus aureus / Q000502:physiology*
D001426:Bacterial Proteins; D020543:Proteome; C079011:SigB protein, Bacteria; D012808:Sigma Factor
Host–pathogen interactions; In vivo-proteomics; Internalization; S. aureus; SigB; Sigma factor B