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PDBsum entry 1tf2
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Protein transport
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PDB id
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1tf2
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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A large conformational change of the translocation atpase seca.
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Authors
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A.R.Osborne,
W.M.Clemons,
T.A.Rapoport.
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Ref.
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Proc Natl Acad Sci U S A, 2004,
101,
10937-10942.
[DOI no: ]
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PubMed id
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Abstract
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The ATPase SecA mediates the posttranslational translocation of a wide range of
polypeptide substrates through the SecY channel in the cytoplasmic membrane of
bacteria. We have determined the crystal structure of a monomeric form of
Bacillus subtilis SecA at a 2.2-A resolution. A comparison with the previously
determined structures of SecA reveals a nucleotide-independent, large
conformational change that opens a deep groove similar to that in other proteins
that interact with diverse polypeptides. We propose that the open form of SecA
represents an activated state.
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Figure 1.
Fig. 1. Structure of monomeric B. subtilis SecA. Monomeric
B. subtilis SecA is presented as a ribbon diagram. NBF1 is shown
in yellow, NBF2 is shown in blue, the PPXD is shown in orange,
the HSD is shown in green, and the HWD is shown in cyan. ADP is
shown in a ball-and-stick representation. The images were
prepared by using MOLSCRIPT (40), RASTER3D (41), or SPOCK
(available at http://mackerel.tamu.edu/spock).
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Figure 3.
Fig. 3. Domain movements in monomeric SecA. Ribbon diagram
of monomeric B. subtilis SecA in the open conformation (a) and
of a single subunit of dimeric B. subtilis SecA in the closed
conformation (b). Color codes are as described for Fig. 1. The
first and last helices in the PPXD are represented as cylinders
to better visualize the transition between the conformations.
The arrows in a indicate the movements that are required to
convert the open conformation to the closed conformation. The
side chains of residues 232 and 773 are shown in red in stick
representation. Corresponding E. coli SecA residue numbers are
given in parentheses. These residues were mutated to cysteines
in E. coli SecA, and the accessibility of residue 824 to a
modification reagent was used to probe the transition from the
closed to the open conformation.
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