3J9O

CryoEM structure of a type VI secretion system

Summary for 3J9O

• Entry DOI: 10.2210/pdb3j9o/pdb
• EMDB information: 6266
• Descriptor: Intracellular growth locus protein A, Intracellular growth locus protein B (2 entities in total)
• Functional Keywords: t6ss, structural protein
• Biological source: Francisella tularensis subsp. novicida U112; More
• Total number of polymer chains: 12
• Total formula weight: 473683.12

Authors

Clemens, D.L.,Ge, P.,Lee, B.-Y.,Horwitz, M.A.,Zhou, Z.H. (deposition date: 2015-02-11, release date: 2015-03-18, Last modification date: 2024-02-21)

Primary citation

Clemens, D.L.,Ge, P.,Lee, B.Y.,Horwitz, M.A.,Zhou, Z.H.
Atomic Structure of T6SS Reveals Interlaced Array Essential to Function.
Cell(Cambridge,Mass.), 160:940-951, 2015

PubMed Abstract: Type VI secretion systems (T6SSs) are newly identified contractile nanomachines that translocate effector proteins across bacterial membranes. The Francisella pathogenicity island, required for bacterial phagosome escape, intracellular replication, and virulence, was presumed to encode a T6SS-like apparatus. Here, we experimentally confirm the identity of this T6SS and, by cryo electron microscopy (cryoEM), show the structure of its post-contraction sheath at 3.7 Å resolution. We demonstrate the assembly of this T6SS by IglA/IglB and secretion of its putative effector proteins in response to environmental stimuli. The sheath has a quaternary structure with handedness opposite that of contracted sheath of T4 phage tail and is organized in an interlaced two-dimensional array by means of β sheet augmentation. By structure-based mutagenesis, we show that this interlacing is essential to secretion, phagosomal escape, and intracellular replication. Our atomic model of the T6SS will facilitate design of drugs targeting this highly prevalent secretion apparatus.

PubMed: 25723168
DOI: 10.1016/j.cell.2015.02.005

Experimental method

ELECTRON MICROSCOPY (3.7 Å)