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PDBsum entry 3h3u
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Transcription
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PDB id
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3h3u
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References listed in PDB file
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Key reference
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Title
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Mapping conformational transitions in cyclic AMP receptor protein: crystal structure and normal-Mode analysis of mycobacterium tuberculosis apo-Camp receptor protein.
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Authors
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P.Kumar,
D.C.Joshi,
M.Akif,
Y.Akhter,
S.E.Hasnain,
S.C.Mande.
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Ref.
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Biophys J, 2010,
98,
305-314.
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PubMed id
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Abstract
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Cyclic AMP (cAMP) receptor protein, which acts as the sensor of cAMP levels in
cells, is a well-studied transcription factor that is best known for allosteric
changes effected by the binding of cAMP. Although genetic and biochemical data
on the protein are available from several sources, structural information about
the cAMP-free protein has been lacking. Therefore, the precise atomic events
that take place upon binding of cAMP, leading to conformational changes in the
protein and its activation to bind DNA, have been elusive. In this work we
solved the cAMP-free crystal structure of the Mycobacterium tuberculosis homolog
of cAMP receptor protein at 2.9 A resolution, and carried out normal-mode
analysis to map conformational transitions among its various conformational
states. In our structure, the cAMP-binding domain holds onto the DNA-binding
domain via strong hydrophobic interactions, thereby freezing the latter in a
conformation that is not competent to bind DNA. The two domains release each
other in the presence of cAMP, making the DNA-binding domain more flexible and
allowing it to bind its cognate DNA via an induced-fit mechanism. The structure
of the cAMP-free protein and results of the normal-mode analysis therefore
highlight an elegant mechanism of the allosteric changes effected by the binding
of cAMP.
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