 |
PDBsum entry 1v2e
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Crystal structures of glutamine:phenylpyruvate aminotransferase from thermus thermophilus hb8: induced fit and substrate recognition.
|
|
|
Authors
|
|
M.Goto,
R.Omi,
I.Miyahara,
A.Hosono,
H.Mizuguchi,
H.Hayashi,
H.Kagamiyama,
K.Hirotsu.
|
|
|
Ref.
|
|
J Biol Chem, 2004,
279,
16518-16525.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
The following three-dimensional structures of three forms of
glutamine:phenylpyruvate aminotransferase from Thermus thermophilus HB8 have
been determined and represent the first x-ray analysis of the enzyme: the
unliganded pyridoxal 5'-phosphate form at 1.9 A resolution and two complexes
with 3-phenylpropionate and alpha-keto-gamma-methylthiobutyrate at 2.35 and 2.6
A resolution, respectively. The enzyme shows high activity toward phenylalanine,
tyrosine, tryptophan, kynurenine, methionine, and glutamine. The enzyme is a
homodimer, and each subunit is divided into an N-terminal arm and small and
large domains. Based on its folding, the enzyme belongs to fold type I,
aminotransferase subclass Ib. The subclass I aminotransferases whose structures
have so far been determined exhibit a large movement of the small domain region
upon binding of a substrate. Similarly, the glutamine:phenylpyruvate
aminotransferase undergoes a large movement in part of the small domain to close
the active site. The active-site pocket has a shape and size suitable to enclose
the side chain of an aromatic amino acid or that of methionine. The inner side
of the pocket is mostly hydrophobic, but also has polar sites. The kynurenine
complex generated by computer modeling fits the pocket of the enzyme and its
hydrophilic groups interact with the polar sites of the pocket.
|
|
|
|
|
|
|
|
Figure 5.
FIG. 5. Schematic diagram showing hydrogen bond and salt
bridge interactions of the active-site residues. Putative
interactions are shown by dotted lines if the acceptor and donor
are less than 3.5 Å apart. Phe-112 and Val-193, which
sandwich the pyridine ring of PLP, are omitted for clarity. A,
the unliganded ttGlnAT in the closed form. B, the ttGlnAT
complex with 3PP. The hydrogen bonds between Ser-13 and Asp-113
have been omitted for clarity.
|
|
Figure 6.
FIG. 6. Superimposition of the active site of the
ttGlnAT·kynurenine complex model onto ttGlnAT·3PP.
The residues that represent the ttGlnAT· kynurenine
complex and ttGlnAT·3PP are shown in brown and deep blue,
respectively. Kynurenine and 3PP are represented by thick lines
in pale blue and brown. The oxygen and nitrogen atoms of
kynurenine and 3PP are colored red and deep blue, respectively.
The dotted lines (green) show the hydrogen bonding interactions
of the amino and carbonyl groups of the 3-anthraniloyl moiety of
kynurenine with Asp-113 and Tyr-57^*, respectively.
|
|
|
|
|
|
The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2004,
279,
16518-16525)
copyright 2004.
|
|
|
|
|
|
|
