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PDBsum entry 1zym
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Phosphotransferase
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PDB id
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1zym
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Contents |
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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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The first step in sugar transport: crystal structure of the amino terminal domain of enzyme i of the e. Coli pep: sugar phosphotransferase system and a model of the phosphotransfer complex with hpr.
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Authors
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D.I.Liao,
E.Silverton,
Y.J.Seok,
B.R.Lee,
A.Peterkofsky,
D.R.Davies.
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Ref.
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Structure, 1996,
4,
861-872.
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PubMed id
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Abstract
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BACKGROUND: The bacterial phosphoenolpyruvate (PEP): sugar phosphotransferase
system (PTS) transports exogenous hexose sugars through the membrane and tightly
couples transport with phosphoryl transfer from PEP to the sugar via several
phosphoprotein intermediates. The phosphate group is first transferred to enzyme
I, second to the histidine-containing phosphocarrier protein HPr, and then to
one of a number of sugar-specific enzymes II. The structures of several HPrs and
enzymes IIA are known. Here we report the structure of the N-terminal half of
enzyme I from Escherichia coli (EIN). RESULTS: The crystal structure of EIN (MW
approximately 30 kDa) has been determined and refined at 2.5 A resolution. It
has two distinct structural subdomains; one contains four alpha helices arranged
as two hairpins in a claw-like conformation. The other consists of a beta
sandwich containing a three-stranded antiparallel beta sheet and a four-stranded
parallel beta sheet, together with three short alpha helices. Plausible models
of complexes between EIN and HPr can be made without assuming major structural
changes in either protein. CONCLUSIONS: The alpha/beta subdomain of EIN is
topologically similar to the phosphohistidine domain of the enzyme pyruvate
phosphate dikinase, which is phosphorylated by PEP on a histidyl residue but
does not interact with HPr. It is therefore likely that features of this
subdomain are important in the autophosphorylation of enzyme I. The helical
subdomain of EIN is not found in pyruvate phosphate dikinase; this subdomain is
therefore more likely to be involved in phosphoryl transfer to HPr.
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