Sweet host revenge: galectins and GBPs join forces at broken membranes

Summary
Most bacterial pathogens enter and exit eukaryotic cells during their journey through the vertebrate host. In order to endure inside a eukaryotic cell, bacterial invaders commonly employ bacterial secretion systems to inject host cells with virulence factors that co‐opt the host's membrane trafficking systems and thereby establish specialized pathogen‐containing vacuoles (PVs) as intracellular niches permissive for microbial growth and survival. To defend against these microbial adversaries hiding inside PVs, host organisms including humans evolved an elaborate cell‐intrinsic armory of antimicrobial weapons that include noxious gases, antimicrobial peptides, degradative enzymes and pore‐forming proteins. This impressive defense machinery needs to be accurately delivered to PVs, in order to fight off vacuole‐dwelling pathogens. Here, I discuss recent evidence that the presence of bacterial secretion systems at PVs and the associated destabilization of PV membranes attract such antimicrobial delivery systems consisting of sugar‐binding galectins as well as dynamin‐like guanylate binding proteins (GBPs). I will review recent advances in our understanding of intracellular immune recognition of PVs by galectins and GBPs, discuss how galectins and GBPs control host defense and highlight important avenues of future research in this exciting area of cell‐autonomous immunity.

Source: Cellular Microbiology - October 1, 2017 Category: Microbiology Authors: J örn Coers Tags: MICROREVIEW Source Type: research