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PDBsum entry 1qo2
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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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Structural evidence for evolution of the beta/alpha barrel scaffold by gene duplication and fusion.
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Authors
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D.Lang,
R.Thoma,
M.Henn-Sax,
R.Sterner,
M.Wilmanns.
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Ref.
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Science, 2000,
289,
1546-1550.
[DOI no: ]
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PubMed id
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Abstract
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The atomic structures of two proteins in the histidine biosynthesis pathway
consist of beta/alpha barrels with a twofold repeat pattern. It is likely that
these proteins evolved by twofold gene duplication and gene fusion from a common
half-barrel ancestor. These ancestral domains are not visible as independent
domains in the extant proteins but can be inferred from a combination of
sequence and structural analysis. The detection of subdomain structures may be
useful in efforts to search genome sequences for functionally and structurally
related proteins.
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Figure 1.
Fig. 1. Atomic structures of HisA (upper panel) and HisF (lower
panel) from Thermotoga maritima in ribbon presentations (29).
View from the COOH-terminal face of the central  barrel,
left; side view, center; and view from the NH[2]-terminal face
of the barrel, right. HisF contains two phosphate ions bound to
the active site, shown as space-filling models (red). The strands
and  helices
of the central eightfold / barrel are
in orange and yellow, respectively. Loops at the NH[2]- and
COOH-terminal faces of the barrel are in cyan and green,
respectively. Some loops contain additional secondary structural
elements. The NH[2]- and COOH-termini are labeled when visible.
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Figure 3.
Fig. 3. Model for the evolution of the / barrel
scaffold by twofold gene duplication. The first gene duplication
generates two initially identical half-barrels that are then
fused and adapted into an ancestral / barrel. A
second gene duplication step leads to the diversification of the
ancestral / barrel
into two enzymes with distinct catalytic activities.
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The above figures are
reprinted
by permission from the AAAs:
Science
(2000,
289,
1546-1550)
copyright 2000.
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Secondary reference #1
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Title
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Efficient expression, Purification and crystallisation of two hyperthermostable enzymes of histidine biosynthesis.
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Authors
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R.Thoma,
G.Obmolova,
D.A.Lang,
M.Schwander,
P.Jenö,
R.Sterner,
M.Wilmanns.
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Ref.
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FEBS Lett, 1999,
454,
1-6.
[DOI no: ]
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PubMed id
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Figure 2.
Fig. 2. Reversed phase HPLC testifies to a high purity
of [SeMet]tHisF. Elution of 160 μg protein was performed at 1
ml/min with an acetonitrile gradient (1.6–64%, dotted line) in
0.08% trifluroacetic acid and monitored on-line at 278 nm.
[SeMet]tHisF eluted as a symmetrical peak at 58 min and
integration of the peak areas yielded a purity of at least 98%.
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Figure 3.
Fig. 3. [SeMet]tHisF is completely labelled with SeMet.
Electrospray mass spectra of tHisF (A) and [SeMet]tHisF (B) were
obtained on a TSQ7000 triple quadrupole mass spectrometer. The
labelled peaks indicate the charge states of measured m/z values
of the two proteins. [M+H]^+ indicates the mass of the two
proteins (27 723.5±3.1 Da for tHisF and 27 959±3.6 Da for
[SeMet]tHisF) as obtained after deconvolution of the measured
m/z values. The mass difference of 236 Da shows that all five
methionine residues in tHisF are completely replaced by SeMet in
[SeMet]tHisF.
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The above figures are
reproduced from the cited reference
with permission from the Federation of European Biochemical Societies
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