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PDBsum entry 1xbn
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Signaling protein
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PDB id
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1xbn
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References listed in PDB file
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Key reference
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Title
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Femtomolar sensitivity of a no sensor from clostridium botulinum.
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Authors
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P.Nioche,
V.Berka,
J.Vipond,
N.Minton,
A.L.Tsai,
C.S.Raman.
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Ref.
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Science, 2004,
306,
1550-1553.
[DOI no: ]
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PubMed id
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Abstract
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Nitric oxide (NO) is extremely toxic to Clostridium botulinum, but its molecular
targets are unknown. Here, we identify a heme protein sensor (SONO) that
displays femtomolar affinity for NO. The crystal structure of the SONO heme
domain reveals a previously undescribed fold and a strategically placed tyrosine
residue that modulates heme-nitrosyl coordination. Furthermore, the domain
architecture of a SONO ortholog cloned from Chlamydomonas reinhardtii indicates
that NO signaling through cyclic guanosine monophosphate arose before the origin
of multicellular eukaryotes. Our findings have broad implications for
understanding bacterial responses to NO, as well as for the activation of
mammalian NO-sensitive guanylyl cyclase.
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Figure 2.
Fig. 2. Three-dimensional structure of TT-SONO[HD]. Ribbon
diagram depicts residues 1 to 181 of the protein. The heme
prosthetic group (red) and the histidine coordinating its iron
are also shown.
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Figure 3.
Fig. 3. Omit difference electron density map (F[obs] - F[calc])
of the heme pocket. Maps are shown at 3  level. Oxygen
ligand density is in blue. Dotted line indicates that the
phenolic -OH of Tyr140 is within hydrogen-bonding distance of
the oxygen ligand.
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The above figures are
reprinted
by permission from the AAAs:
Science
(2004,
306,
1550-1553)
copyright 2004.
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