Defining Assembly Pathways by Fluorescence Microscopy.

Bacterial secretion systems are among the largest protein complexes in prokaryotes and display remarkably complex architectures. Their assembly often follows clearly defined pathways. Deciphering these pathways not only reveals how bacteria accomplish building these large functional complexes but can provide crucial information on the interactions and subcomplexes within secretion systems, their distribution within bacteria, and even functional insights. The emergence of fluorescent proteins has provided a new powerful tool for biological imaging, and the use of fluorescently labeled components presents an interesting method to accurately define the biogenesis of macromolecular complexes. Here we describe the use of this method to decipher the assembly pathway of bacterial secretion systems.