6V9Z

Cryo-EM structure of PCAT1 bound to its CtA peptide substrate

Summary for 6V9Z

• Entry DOI: 10.2210/pdb6v9z/pdb
• EMDB information: 21132
• Descriptor: ABC-type bacteriocin transporter, CtA (2 entities in total)
• Functional Keywords: atp-binding cassette, protein transport
• Biological source: Hungateiclostridium thermocellum (strain ATCC 27405 / DSM 1237 / JCM 9322 / NBRC 103400 / NCIMB 10682 / NRRL B-4536 / VPI 7372); More
• Total number of polymer chains: 4
• Total formula weight: 182733.22

Authors

Kieuvongngam, V.,Oldham, M.L.,Chen, J. (deposition date: 2019-12-16, release date: 2020-01-22, Last modification date: 2024-03-06)

Primary citation

Kieuvongngam, V.,Olinares, P.D.B.,Palillo, A.,Oldham, M.L.,Chait, B.T.,Chen, J.
Structural basis of substrate recognition by a polypeptide processing and secretion transporter.
Elife, 9:-, 2020

PubMed Abstract: The peptidase-containing ATP-binding cassette transporters (PCATs) are unique members of the ABC transporter family that proteolytically process and export peptides and proteins. Each PCAT contains two peptidase domains that cleave off the secretion signal, two transmembrane domains forming a translocation pathway, and two nucleotide-binding domains that hydrolyze ATP. Previously the crystal structures of a PCAT from (PCAT1) were determined in the absence and presence of ATP, revealing how ATP binding regulates the protease activity and access to the translocation pathway. However, how the substrate CtA, a 90-residue polypeptide, is recognized by PCAT1 remained elusive. To address this question, we determined the structure of the PCAT1-CtA complex by electron cryo-microscopy (cryo-EM) to 3.4 Å resolution. The structure shows that two CtAs are bound via their N-terminal leader peptides, but only one is positioned for cleavage and translocation. Based on these results, we propose a model of how substrate cleavage, ATP hydrolysis, and substrate translocation are coordinated in a transport cycle.

PubMed: 31934861
DOI: 10.7554/eLife.51492

Experimental method

ELECTRON MICROSCOPY (3.35 Å)