3JUX

Structure of the translocation ATPase SecA from Thermotoga maritima

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.10 Å
  • R-Value Free: 0.303 
  • R-Value Work: 0.227 

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Literature

Conformational flexibility and peptide interaction of the translocation ATPase SecA.

Zimmer, J., Rapoport, T.A.

(2009) J Mol Biol 394: 606-612

  • DOI: 10.1016/j.jmb.2009.10.024
  • Primary Citation of Related Structures:  
    3JUX, 3JV2

  • PubMed Abstract: 

    • The SecA ATPase forms a functional complex with the protein-conducting SecY channel to translocate polypeptides across the bacterial cell membrane. SecA recognizes the translocation substrate and catalyzes its unidirectional movement through the SecY channel ...

    The SecA ATPase forms a functional complex with the protein-conducting SecY channel to translocate polypeptides across the bacterial cell membrane. SecA recognizes the translocation substrate and catalyzes its unidirectional movement through the SecY channel. The recent crystal structure of the Thermotoga maritima SecA-SecYEG complex shows the ATPase in a conformation where the nucleotide-binding domains (NBDs) have closed around a bound ADP-BeFx complex and SecA's polypeptide-binding clamp is shut. Here, we present the crystal structure of T. maritima SecA in isolation, determined in its ADP-bound form at 3.1 A resolution. SecA alone has a drastically different conformation in which the nucleotide-binding pocket between NBD1 and NBD2 is open and the preprotein cross-linking domain has rotated away from both NBDs, thereby opening the polypeptide-binding clamp. To investigate how this clamp binds polypeptide substrates, we also determined a structure of Bacillus subtilis SecA in complex with a peptide at 2.5 A resolution. This structure shows that the peptide augments the highly conserved beta-sheet at the back of the clamp. Taken together, these structures suggest a mechanism by which ATP hydrolysis can lead to polypeptide translocation.

    Organizational Affiliation: 

    Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Protein translocase subunit secAA822Thermotoga maritimaMutation(s): 0 
Gene Names: secA, TM_1578
UniProt
Find proteins for Q9X1R4 (Thermotoga maritima (strain ATCC 43589 / DSM 3109 / JCM 10099 / NBRC 100826 / MSB8))
Explore Q9X1R4 
Go to UniProtKB:  Q9X1R4
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ADP (Subject of Investigation/LOI)
Query on ADP
Download Ideal Coordinates CCD File 
 C [auth A]ADENOSINE-5'-DIPHOSPHATE
C10 H15 N5 O10 P2
XTWYTFMLZFPYCI-KQYNXXCUSA-N		 Ligand Interaction
MG
Query on MG
Download Ideal Coordinates CCD File 
 B [auth A]MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.10 Å
  • R-Value Free: 0.303 
  • R-Value Work: 0.227 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.533α = 90
b = 119.403β = 90
c = 120.82γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

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Entry History 

Deposition Data

  • Deposited Date: 2009-09-15 
  • Released Date: 2009-10-20 
    • Deposition Author(s): Zimmer, J.

Revision History  (Full details and data files)

  • Version 1.0: 2009-10-20
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance