Type I Secretion Systems (T1SS)

Type I Secretion Systems (T1SS) are one-step secretion systems that move proteins from the cytoplasm directly outside the cell. They are the simplest of the one-step secretion systems, and a bacterial cell may contain many of these systems for the export of different proteins.

Willey et al. 2023 McGraw Hill, USA, ISBN 978-1-265-12303-1

Components and Function

Each Type I Secretion Systems (T1SS) has three components:

1. ABC (ATP Binding Cassette) Transporter: Located in the plasma membrane, this component is specific for a single substrate.


2. Membrane Fusion Protein: Bridges the periplasm.


3. Outer Membrane Barrel: A common structure to multiple Type I Secretion Systems (T1SS) that spans the outer membrane.

These components assemble only …