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PDBsum entry 2oge
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References listed in PDB file
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Key reference
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Title
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Molecular architecture of desv from streptomyces venezuelae: a plp-Dependent transaminase involved in the biosynthesis of the unusual sugar desosamine.
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Authors
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E.S.Burgie,
J.B.Thoden,
H.M.Holden.
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Ref.
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Protein Sci, 2007,
16,
887-896.
[DOI no: ]
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PubMed id
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Abstract
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Desosamine is a 3-(dimethylamino)-3,4,6-trideoxyhexose found in certain
macrolide antibiotics such as the commonly prescribed erythromycin. Six enzymes
are required for its biosynthesis in Streptomyces venezuelae. The focus of this
article is DesV, which catalyzes the PLP-dependent replacement of a 3-keto group
with an amino functionality in the fifth step of the pathway. For this study the
three-dimensional structures of both the internal aldimine and the ketimine
intermediate with glutamate were determined to 2.05 A resolution. DesV is a
homodimer with each subunit containing 12 alpha-helical regions and 12
beta-strands that together form three layers of sheet. The structure of the
internal aldimine demonstrates that the PLP-cofactor is held in place by
residues contributed from both subunits (Asp 164 and Gln 167 from Subunit I and
Tyr 221 and Asn 235 from Subunit II). When the ketimine intermediate is present
in the active site, the loop defined by Gln 225 to Ser 228 from Subunit II
closes down upon the active site. The structure of DesV is similar to another
sugar-modifying enzyme referred to as PseC. This enzyme is involved in the
biosynthesis of pseudaminic acid, which is a sialic acid-like nonulosonate found
in the flagellin of Helicobacter pylori. In the case of PseC, however, the amino
group is transferred to the C-4 rather than the C-3 position. Details concerning
the structural analysis of DesV and a comparison of its molecular architecture
to that of PseC are presented.
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Figure 3.
Figure 3. The structure of the DesV ketimine intermediate. Electron density corresponding to the ketimine intermediate is presented in
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Figure 4.
Figure 4. Superposition of the regions surrounding the internal aldimine versus the ketimine intermediate. The model corresponding
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The above figures are
reprinted
by permission from the Protein Society:
Protein Sci
(2007,
16,
887-896)
copyright 2007.
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