Methylglyoxal synthase (MGS, EC 4.2.3.3) (see <PDOC01037>), which catalyzes
the conversion of dihydroxyacetone phosphate (DHAP) to methylglyoxal (MG) and
inorganic phosphate, has been found in many organisms, including enteric
bacteria, some gram-positive bacteria, a number of archaebacteria, several
yeast species and goat liver [1,2]. A domain similar to the full-length MGS is
found in [3]:
Bifunctional purine biosynthesis protein PurH, also known as
aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase (AICAR
Tfase)/inosine 50-monophosphate (IMP) cyclohydrolase (IMPCH) (ATIC)
(EC 2.1.2.3). In bacteria and eukaryotes, the last two steps of de novo
purine biosynthesis are catalyzed by PurH, which is composed of two
functionally independent domains linked by a flexible region. The N-
terminal MGS-like domain possesses IMPCH activity and the C-terminal domain
possesses AICAR Tfase activity. The MGS-like domain with IMPCH activity
catalyzes the intramolecular cyclization of 5-formyl-AICAR (FAICAR) to IMP
[4,5,6,7].
Carbamoyl phosphate synthetase (CPS) catalyzes the formation of carbamoyl
phosphate from one molecule of bicarbonate, two molecules of Mg(2+)ATP and
one molecule of glutamine or ammonia depending upon the particular form of
the enzyme. The enzyme is an α,β-heterodimer consisting of a small
subunit that hydrolyzes glutamine and a large subunit that catalyzes the
two required phosphorylation events. The large subunit consists of four
structural units: the carboxyphosphate synthetic component, the
oligomerization domain, the carbamoyl phosphate synthetic component and the
MGS-like allosteric domain. The binding of various ligands by the MGS-like
domain allosterically regulates CPS [8,9].
The main core of the MGS-like domain, a modified 'Rossmann' fold, is
characterized by a five stranded parallel β-sheet flanked on either side by
three and five α-helices, respectively (see <PDB:1PKX>) [6,8]. MGS-like
domains share a conserved phosphate binding site [3,7].
The profile we developed covers the entire MGS-like domain.
Axelrod H.L. McMullan D. Krishna S.S. Miller M.D. Elsliger M.-A. Abdubek P. Ambing E. Astakhova T. Carlton D. Chiu H.-J. Clayton T. Duan L. Feuerhelm J. Grzechnik S.K. Hale J. Han G.W. Haugen J. Jaroszewski L. Jin K.K. Klock H.E. Knuth M.W. Koesema E. Morse A.T. Nigoghossian E. Okach L. Oommachen S. Paulsen J. Quijano K. Reyes R. Rife C.L. van den Bedem H. Weekes D. White A. Wolf G. Xu Q. Hodgson K.O. Wooley J. Deacon A.M. Godzik A. Lesley S.A. Wilson I.A.
Title
Crystal structure of AICAR transformylase IMP cyclohydrolase (TM1249) from Thermotoga maritima at 1.88 A resolution.
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