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PDBsum entry 3glb
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Transcription
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PDB id
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3glb
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References listed in PDB file
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Key reference
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Title
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Inducer responses of benm, A lysr-Type transcriptional regulator from acinetobacter baylyi ADP1.
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Authors
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S.H.Craven,
O.C.Ezezika,
S.Haddad,
R.A.Hall,
C.Momany,
E.L.Neidle.
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Ref.
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Mol Microbiol, 2009,
72,
881-894.
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PubMed id
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Abstract
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BenM and CatM control transcription of a complex regulon for aromatic compound
degradation. These Acinetobacter baylyi paralogues belong to the largest family
of prokaryotic transcriptional regulators, the LysR-type proteins. Whereas BenM
activates transcription synergistically in response to two effectors, benzoate
and cis,cis-muconate, CatM responds only to cis,cis-muconate. Here,
site-directed mutagenesis was used to determine the physiological significance
of an unexpected benzoate-binding pocket in BenM discovered during structural
studies. Residues in BenM were changed to match those of CatM in this
hydrophobic pocket. Two BenM residues, R160 and Y293, were found to mediate the
response to benzoate. Additionally, alteration of these residues caused benzoate
to inhibit activation by cis,cis-muconate, positioned in a separate primary
effector-binding site of BenM. The location of the primary site, in an
interdomain cleft, is conserved in diverse LysR-type regulators. To improve
understanding of this important family, additional regulatory mutants were
analysed. The atomic-level structures were characterized of the effector-binding
domains of variants that do not require inducers for activation, CatM(R156H) and
BenM(R156H,T157S). These structures clearly resemble those of the wild-type
proteins in their activated muconate-bound complexes. Amino acid replacements
that enable activation without effectors reside at protein interfaces that may
impact transcription through effects on oligomerization.
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