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PDBsum entry 5eat
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Isoprenoid synthase
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PDB id
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5eat
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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 cyclic terpene biosynthesis by tobacco 5-Epi-Aristolochene synthase.
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Authors
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C.M.Starks,
K.Back,
J.Chappell,
J.P.Noel.
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Ref.
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Science, 1997,
277,
1815-1820.
[DOI no: ]
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PubMed id
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Abstract
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Terpene cyclases catalyze the synthesis of cyclic terpenes with 10-, 15-, and
20-carbon acyclic isoprenoid diphosphates as substrates. Plants have been a
source of these natural products by providing a homologous set of terpene
synthases. The crystal structures of 5-epi-aristolochene synthase, a
sesquiterpene cyclase from tobacco, alone and complexed separately with two
farnesyl diphosphate analogs were analyzed. These structures reveal an
unexpected enzymatic mechanism for the synthesis of the bicyclic product,
5-epi-aristolochene, and provide a basis for understanding the stereochemical
selectivity displayed by other cyclases in the biosynthesis of pharmacologically
important cyclic terpenes. As such, these structures provide templates for the
engineering of novel terpene cyclases.
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Figure 2.
Fig. 2. Stereo views of the TEAS active site. Blue dashed
lines are hydrogen bonds; green dashed lines are coordination
bonds. The^ top panel illustrates the TEAS·FHP complex.
FHP is emphasized^ with dark gray bonds. The lower panel
illustrates the TEAS·F[3]FPP complex. The diphosphate
moiety is emphasized with dark bonds. The rest of the F[3]-FPP
molecule, which exhibits weak electron density, is indicated
with dashed bonds. Figure was prepared with MOLSCRIPT (24) and
RASTER3D (24).
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Figure 3.
Fig. 3. Proposed catalytic mechanisms of TEAS and HVS based
on the TEAS crystal structures. (A) through (F) are reaction
steps common to both TEAS and HVS. (G[1]) through (I[1]) are
specific to TEAS, and (G[2]) through (I[2]) are^ specific to
HVS. Carbocations are yellow, protons are light blue, and
aromatic quadrupoles are indicated with purple lines.
Intermediate^ structures are numbered according to the acyclic
precursor, FPP (A). Figure was generated with Chem3D
(CambridgeSoft).
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The above figures are
reprinted
by permission from the AAAs:
Science
(1997,
277,
1815-1820)
copyright 1997.
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Secondary reference #1
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Title
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Expression of a plant sesquiterpene cyclase gene in escherichia coli.
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Authors
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K.Back,
S.Yin,
J.Chappell.
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Ref.
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Arch Biochem Biophys, 1994,
315,
527-532.
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PubMed id
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Secondary reference #2
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Title
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Purification and characterization of an inducible sesquiterpene cyclase from elicitor-Treated tobacco cell suspension cultures.
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Authors
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U.Vögeli,
J.W.Freeman,
J.Chappell.
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Ref.
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Plant Physiol, 1990,
93,
182-187.
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PubMed id
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