 |
PDBsum entry 1bjo
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Aminotransferase
|
PDB id
|
|
|
|
1bjo
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Crystal structure of phosphoserine aminotransferase from escherichia coli at 2.3 a resolution: comparison of the unligated enzyme and a complex with alpha-Methyl-L-Glutamate.
|
|
|
Authors
|
|
G.Hester,
W.Stark,
M.Moser,
J.Kallen,
Z.Marković-Housley,
J.N.Jansonius.
|
|
|
Ref.
|
|
J Mol Biol, 1999,
286,
829-850.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
|
|
|
Abstract
|
|
|
Phosphoserine aminotransferase (PSAT; EC 2.6.1.52), a member of subgroup IV of
the aminotransferases, catalyses the conversion of 3-phosphohydroxypyruvate to
l-phosphoserine. The crystal structure of PSAT from Escherichia coli has been
solved in space group P212121 using MIRAS phases in combination with density
modification and was refined to an R-factor of 17.5% (Rfree=20.1 %) at 2.3 A
resolution. In addition, the structure of PSAT in complex with
alpha-methyl-l-glutamate (AMG) has been refined to an R-factor of 18.5%
(Rfree=25.1%) at 2.8 A resolution. Each subunit (361 residues) of the PSAT
homodimer is composed of a large pyridoxal-5'-phosphate binding domain (residues
16-268), consisting of a seven-stranded mainly parallel beta-sheet, two
additional beta-strands and seven alpha-helices, and a small C-terminal domain,
which incorporates a five-stranded beta-sheet and two alpha-helices. A
three-dimensional structural comparison to four other vitamin B6-dependent
enzymes reveals that three alpha-helices of the large domain, as well as an
N-terminal domain (subgroup II) or subdomain (subgroup I) are absent in PSAT.
Its only 15 N-terminal residues form a single beta-strand, which participates in
the beta-sheet of the C-terminal domain. The cofactor is bound through an
aldimine linkage to Lys198 in the active site. In the PSAT-AMG complex Ser9 and
Arg335 bind the AMG alpha-carboxylate group while His41, Arg42 and His328 are
involved in binding the AMG side-chain. Arg77 binds the AMG side-chain
indirectly through a solvent molecule and is expected to position itself during
catalysis between the PLP phosphate group and the substrate side-chain.
Comparison of the active sites of PSAT and aspartate aminotransferase suggests a
similar catalytic mechanism, except for the transaldimination step, since in
PSAT the Schiff base is protonated. Correlation of the PSAT crystal structure to
a published profile sequence analysis of all subgroup IV members allows active
site modelling of nifs and the proposal of a likely molecular reaction mechanism.
|
|
|
|
|
|
|
|
Figure 1.
Figure 1. Nomenclature of atoms for PLP-Lys198 aldimine and
for the external aldimine with AMG.
|
|
Figure 5.
Figure 5. Comparison of structure topologies by
superpositions of C^α traces of PSAT with those of DGD and E.
coli AAT, respectively, using DALI algorithm [Holm and Sander
1993]. In both stereo diagrams PSAT is displayed in fat lines
while the superimposed molecule is displayed in thin lines. N
and C termini are labelled. (a) Stereo diagram of superimposed
C^α traces of closed form of AAT and PSAT-AMG complex. (b)
Stereo diagram of superimposed C^α traces of DGD and native
PSAT. Pictures generated using program BOBSCRIPT [Kraulis 1991
and Esnouf 1998]. Program RASTER3D was used additionally to
generate (b) [Bacon and Anderson 1988 and Merrit and Murphy
1994].
|
|
|
|
|
|
The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(1999,
286,
829-850)
copyright 1999.
|
|
|
Secondary reference #1
|
|
|
Title
|
|
The three dimensional structure of phosphoserine aminotransferase from escherichia coli
|
|
|
Authors
|
|
W.Stark,
J.Kallen,
Z.Markovic-Housley,
B.Fol,
M.Kania,
J.N.Jansonius.
|
|
|
Ref.
|
|
enzymes dependent on ...
|
|
|
|
Secondary reference #2
|
|
|
Title
|
|
Crystallographic and solution studies on phosphoserine aminotransferase (psat) from e. Coli
|
|
|
Authors
|
|
J.Kallen,
M.Kania,
Z.Markovic-Housley,
M.G.Vincent,
J.N.Jansonius.
|
|
|
Ref.
|
|
biochemistry of vitamin b6: 157 1987 proceedings of the 7th international congress on chemical and biological aspects of vitamin b6 catalysis (in: iub symp ser , ...
|
|
|
|
|
|
|
|
