The 'when and whereabouts' of injected pathogen effectors

Recent Advancements in Tracking Bacterial Effector Protein Translocation

Bacteria-host interactions are characterized by the delivery of bacterial virulence factors, i.e., effectors, into host cells where they counteract host immunity and exploit host responses allowing bacterial survival and spreading. These effectors are translocated into host cells by means of dedicated secretion systems such as the type 3 secretion system (T3SS). A comprehensive understanding of effector translocation in a spatio-temporal manner is of critical importance to gain insights into an effector’s mode of action. Various approaches have been developed to understand timing and order of effector translocation, quantities of translocated effectors and their subcellular localization upon translocation into host cells. Recently, the existing toolset has been expanded by newly developed state-of-the art methods to monitor bacterial effector translocation and dynamics. In this review, we elaborate on reported methods and discuss recent advances and shortcomings in this area of tracking bacterial effector translocation.

Tracking elusive cargo: Illuminating spatio-temporal Type 3 effector protein dynamics using reporters

Type 3 secretion systems form an integral part of the arsenal of many pathogenic bacteria. These injection machines, together with their cargo of subversive effector proteins, are capable of manipulating the cellular environment of the host in order to ensure persistence of the pathogen. In order to fully appreciate the functions of Type 3 effectors, it is necessary to gain spatio‐temporal knowledge of each effector during the process of infection. A number of genetic modifications have been exploited in order to reveal effector protein secretion, translocation and subsequent activity, and localisation within host cells. In this review, we will discuss the many available approaches for tracking effector protein dynamics and discuss the challenges faced to improve the current technologies and gain a clearer picture of effector protein function.

Effective--a database of predicted secreted bacterial proteins

Protein secretion is a key virulence mechanism of pathogenic and symbiotic bacteria, which makes the investigation of secreted proteins ('effectors') crucial for understanding the molecular bacterium-host interactions. Effective (http://effectors.org) is a database of predicted bacterial secreted proteins, implementing two complementary prediction strategies for protein secretion: the identification of eukaryotic-like protein domains and the recognition of signal peptides in amino acid sequences. The Effective web portal provides user-friendly tools for browsing and retrieving comprehensive precalculated predictions for whole bacterial genomes as well as for the interactive prediction of effectors in user-provided protein sequences.