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PDBsum entry 2a7z
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Recombination regulator
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PDB id
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2a7z
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References listed in PDB file
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Key reference
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Title
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Molecular modeling of recx reveals its mode of interaction with reca.
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Authors
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S.Mishra,
P.A.Mazumdar,
J.Dey,
A.K.Das.
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Ref.
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Biochem Biophys Res Commun, 2003,
312,
615-622.
[DOI no: ]
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PubMed id
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Abstract
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The protein RecA is involved in homologous recombination, DNA repair and also
catalyzes DNA strand exchange. RecX gene is downstream of recA and the gene
product RecX is supposed to be important for RecA regulation. Recombinant RecX
is purified to homogeneity, and circular dichroism (CD) and FTIR spectroscopy
show the protein to exist mostly in helical conformation. The fluorescence
emission maxima of the native and the denatured protein and the steady-state
fluorescence quenching studies with acrylamide indicate the presence of
tryptophan residues partially exposed to the bulk solvent. Denaturation studies
with urea and guanidine hydrochloride by use of spectroscopic methods,
fluorescence, and CD also confirm the instability of the protein and unfolding
occurs following a two-state model. Mass spectrometry and gel permeation
chromatography suggest the monomeric form of the protein. Molecular modeling of
RecX represents the molecule as extended and helical bundle in conformity with
the spectroscopic results. To understand the mechanism of RecX in the regulation
of RecA the structural model of RecA-RecX has been discussed. In this proposed
model, entry of RecX into hexameric RecA filament prevents binding of ssDNA and
also inhibits ATPase activity.
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