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PDBsum entry 1yy7
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Transcription
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PDB id
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1yy7
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References listed in PDB file
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Key reference
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Title
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Structural basis for the function of stringent starvation protein a as a transcription factor.
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Authors
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A.M.Hansen,
Y.Gu,
M.Li,
M.Andrykovitch,
D.S.Waugh,
D.J.Jin,
X.Ji.
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Ref.
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J Biol Chem, 2005,
280,
17380-17391.
[DOI no: ]
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PubMed id
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Abstract
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Stringent starvation protein A (SspA) of Escherichia coli is an RNA
polymerase-associated transcriptional activator for the lytic development of
phage P1 and is essential for stationary phase-induced acid tolerance of E.
coli. We report the crystal structure of Yersinia pestis SspA, which is 83%
identical to E. coli SspA in amino acid sequence and is functionally
complementary in supporting the lytic growth of phage P1 and acid resistance of
an E. coli sspA mutant. The structure reveals that SspA assumes the
characteristic fold of glutathione S-transferase (GST). However, SspA lacks GST
activity and does not bind glutathione. Three regions of SspA are flexible, the
N and C termini and the alpha2-helix. The structure also reveals a conserved
surface-exposed pocket composed of residues from a loop between helices alpha3
and alpha4. The functional roles of these structural features were investigated
by assessing the ability of deletion and site-directed mutants to confer acid
resistance of E. coli and to activate transcription from a phage P1 late
promoter, thereby supporting the lytic growth of phage P1. The results indicate
that the flexible regions are not critical for SspA function, whereas the
surface pocket is important for both transcriptional activation of the phage P1
late promoter and acid resistance of E. coli. The size, shape, and property of
the pocket suggest that it mediates protein-protein interactions. SspA orthologs
from Y. pestis, Vibrio cholerae, and Pseudomonas aeruginosa are all functional
in acid resistance of E. coli, whereas only Y. pestis SspA supports phage P1
growth.
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Figure 1.
FIG. 1. Overall structure of Y. pestis SspA. The dimeric
molecule is illustrated as ribbon diagrams (helices as spirals,
 -strands as arrows, and
loops as pipes) with the two domains of each subunit colored in
cyan and orange, respectively. The figure was prepared with
MOL-SCRIPT (65) and Raster3D (66).
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Figure 2.
FIG. 2. Stereoviews showing structural comparisons. A,
comparison between Mol A (blue) and Mol B (cyan) of Y. pestis
SspA. B, comparison between Mol A of Y. pestis SspA (blue, this
work) and one subunit of GST B1-1 in complex with GSH (green,
PDB code 2PMT [PDB]
, Ref. 55). C, comparison between Mol A of Y. pestis SspA (blue,
this work) and Ure2p (red, PDB code 1G6W [PDB]
, Ref. 51). The protein is illustrated as ribbon diagrams
(helices as spirals, -strands as arrows, and
loops as pipes). The figure was prepared with MOLSCRIPT (65).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2005,
280,
17380-17391)
copyright 2005.
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