ThANKs for the repeat: Intracellular pathogens exploit a common eukaryotic domain

Abstract

Bacterial pathogens are renowned cell biologists that subvert detrimental host responses by manipulating eukaryotic protein function. A select group of pathogens use a specialized type IV secretion system (T4SS) as a conduit to deliver an arsenal of proteins into the host cytosol where they interact with host proteins. The translocated "effectors" have garnered increased attention because they uncover novel aspects of host-pathogen interactions at the subcellular level. This review presents a group of effectors termed Anks that possess eukaryotic-like ankyrin repeat domains that mediate proteinprotein interactions and are critical for effector function. Interestingly, most known prokaryotic Anks are produced by bacteria that devote much of their time to replicating inside eukaryotic cells. Ank proteins represent a fascinating and versatile family of effectors exploited by bacterial pathogens and are proving useful as tools to study eukaryotic cell biology.

Figure 1

Ank protein structure. Anks consist of repeating regions that adapt a helix-turn-helix configuration containing antiparallel α-helices. A series of repeats stack into a spring-like curved structure, with β-loops in each turn playing a crucial role in mediating protein-protein interactions. The example shown is a 12-repeat region of mammalian Ankyrin-R, which was solved by Michaely et al. The structure was rendered with iMol using Protein Data Bank coordinates 1N11.