Peptidylprolyl Isomerases, Bacterial Virulence, and Targets for Therapy
An Overview of Peptidylprolyl Isomerases (PPIs) in Bacterial Virulence
Department of Microbial Diseases, UCL-Eastman Dental Institute, University College London, UK
This chapter introduces the reader to individual examples of related families of proteins known as the peptidylprolyl isomerases (PPIs). There is rapidly emerging evidence that human PPIs, such as the cyclophilins, are important secreted biomarkers of inflammation and of various human disease states (Satoh et al. 2010; Bukrinsky et al. 2013; Nigro et al. 2013). For this reason, the cyclophilins and their receptor CD 147 are now seen as important therapeutic targets (Bukrinsky 2015). One important question is whether the secreted PPIs emanating from pathogenic bacteria also bind to CD147, or compete with host PPIs for binding to this receptor. Neissera meningitidis does bind to this receptor, but through its PilE and PilV components (Bernard et al. 2014). Evidence has emerged over the past decades to support the hypothesis that bacteria utilize PPIs in their interactions with the host and that this interaction is actually a twoway process. This chapter will present an abbreviated review of bacterial PPIs (mainly from Legionella pneumophila) as virulence factors, as this topic has been the subject of a number of recent reviews (Rasch et al. 2014; Unal and Steinert 2014, 2015).