Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Biochemistry & Molecular Biology, PROTEIN EXPORT APPARATUS, NEEDLE LENGTH, INNER-ROD, SUBSTRATE-SPECIFICITY, STRUCTURAL-CHARACTERIZATION, BACTERIAL INJECTISOMES, TRANSLOCATOR PROTEINS, MEMBRANE TOPOLOGY, CRYSTAL-STRUCTURE, SORTING PLATFORM, Type III secretion (T3S), Type III secretion system (T3SS), chaperones, energy requirements, injectisome assembly, secretion regulation, Bacterial Proteins, Gram-Negative Bacteria, Nanotechnology, 03 Chemical Sciences, 06 Biological Sciences, 11 Medical and Health Sciences, Developmental Biology, 3101 Biochemistry and cell biology, 3205 Medical biochemistry and metabolomics, 3404 Medicinal and biomolecular chemistry

Abstract:

The Type III secretion system (T3SS) is a protein export pathway that is widespread in Gram-negative bacteria and delivers effector proteins directly into eukaryotic cells. At its core lie the injectisome (a sophisticated transmembrane secretion apparatus) and a complex network of specialized chaperones that target secretory proteins to the antechamber of the injectisome. The assembly of the system, and the subsequent secretion of proteins through it, undergo fine-tuned, hierarchical regulation. Here, we present the current understanding of the injectisome assembly process, secretion hierarchy, and the role of chaperones. We discuss these events in light of available structural and biochemical dissection and propose future directions essential to revealing mechanistic insight into this fascinating nanomachine.