Bacterial Protein Toxins Acting on Small GTPases

Abstract

Numerous bacterial protein toxins and effectors target eukaryotic cells by covalent modification of low molecular mass GTP-binding proteins to manipulate their switch functions. Frequent targets are Rho, Ras, and Rab proteins which are modified by ADP-ribosylation, adenylylation, mono-O-glycosylation, deamidation, transglutamination, phosphocholination, and proteolytic cleavage. Thereby, the GTPases are activated or inactivated. Other bacterial effectors manipulate the cellular functions of small GTPases by mimicking endogenous regulators of the switch proteins. They act as guanine nucleotide exchange factors (GEFs) or GTPase-activating proteins (GAPs). The chapter describes the bacterial toxins and effectors and discusses the functional consequences of their actions.