Related ArticlesThe NMR solution structure of a mutant of the Max b/HLH/LZ free of DNA: insights into the specific and reversible DNA binding mechanism of dimeric transcription factors.
J Mol Biol. 2004 Sep 17;342(3):813-32
Authors: Sauvé S, Tremblay L, Lavigne P
Basic region-helix1-loop-helix2-leucine zipper (b/H(1)LH(2)/LZ) transcription factors bind specific DNA sequence in their target gene promoters as dimers. Max, a b/H(1)LH(2)/LZ transcription factor, is the obligate heterodimeric partner of the related b/H(1)LH(2)/LZ proteins of the Myc and Mad families. These heterodimers specifically bind E-box DNA sequence (CACGTG) to activate (e.g. c-Myc/Max) and repress (e.g. Mad1/Max) transcription. Max can also homodimerize and bind E-box sequences in c-Myc target gene promoters. While the X-ray structure of the Max b/H(1)LH(2)/LZ/DNA complex and that of others have been reported, the precise sequence of events leading to the reversible and specific binding of these important transcription factors is still largely unknown. In order to provide insights into the DNA binding mechanism, we have solved the NMR solution structure of a covalently homodimerized version of a Max b/H(1)LH(2)/LZ protein with two stabilizing mutations in the LZ, and characterized its backbone dynamics from (15)N spin-relaxation measurements in the absence of DNA. Apart from minor differences in the pitch of the LZ, possibly resulting from the mutations in the construct, we observe that the packing of the helices in the H(1)LH(2) domain is almost identical to that of the two crystal structures, indicating that no important conformational change in these helices occurs upon DNA binding. Conversely to the crystal structures of the DNA complexes, the first 14 residues of the basic region are found to be mostly unfolded while the loop is observed to be flexible. This indicates that these domains undergo conformational changes upon DNA binding. On the other hand, we find the last four residues of the basic region form a persistent helical turn contiguous to H(1). In addition, we provide evidence of the existence of internal motions in the backbone of H(1) that are of larger amplitude and longer time-scale (nanoseconds) than the ones in the H(2) and LZ domain. Most interestingly, we note that conformers in the ensemble of calculated structures have highly conserved basic residues (located in the persistent helical turn of the basic region and in the loop) known to be important for specific binding in a conformation that matches that of the DNA-bound state. These partially prefolded conformers can directly fit into the major groove of DNA and as such are proposed to lie on the pathway leading to the reversible and specific DNA binding. In these conformers, the conserved basic side-chains form a cluster that elevates the local electrostatic potential and could provide the necessary driving force for the generation of the internal motions localized in the H(1) and therefore link structural determinants with the DNA binding function. Overall, our results suggests that the Max homodimeric b/H(1)LH(2)/LZ can rapidly and preferentially bind DNA sequence through transient and partially prefolded states and subsequently, adopt the fully helical bound state in a DNA-assisted mechanism or induced-fit.
[NMR paper] NMR studies on the solution structure of a deletion mutant of the transcarboxylase bi
NMR studies on the solution structure of a deletion mutant of the transcarboxylase biotin carrier subunit.
Related Articles NMR studies on the solution structure of a deletion mutant of the transcarboxylase biotin carrier subunit.
Int J Biol Macromol. 2002 Oct 1;30(5):233-42
Authors: Jank MM, Sadowsky JD, Peikert C, Berger S
A deletion mutant of the transcarboxylase biotin carrier protein was completely labeled with 13C and 15N. A multitude of 2D and 3D NMR spectra were recorded and assigned. An NMR solution structure was derived from the data...
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[NMR paper] Fluctuations in free or substrate-complexed lysozyme and a mutant of it detected on x
Fluctuations in free or substrate-complexed lysozyme and a mutant of it detected on x-ray crystallography and comparison with those detected on NMR.
Related Articles Fluctuations in free or substrate-complexed lysozyme and a mutant of it detected on x-ray crystallography and comparison with those detected on NMR.
J Biochem. 2002 May;131(5):701-4
Authors: Ohmura T, Motoshima H, Ueda T, Imoto T
A mutant lysozyme in which Arg14 and His15 were deleted together exhibited higher activity toward glycol chitin than the wild-type lysozyme. Moreover,...
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[NMR paper] Insights into the mechanism of heterodimerization from the 1H-NMR solution structure
Insights into the mechanism of heterodimerization from the 1H-NMR solution structure of the c-Myc-Max heterodimeric leucine zipper.
Related Articles Insights into the mechanism of heterodimerization from the 1H-NMR solution structure of the c-Myc-Max heterodimeric leucine zipper.
J Mol Biol. 1998 Aug 7;281(1):165-81
Authors: Lavigne P, Crump MP, Gagné SM, Hodges RS, Kay CM, Sykes BD
The oncoprotein c-Myc (a member of the helix-loop-helix-leucine zipper (b-HLH-LZ) family of transcription factors) must heterodimerize with the b-HLH-LZ Max...
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[NMR paper] High-resolution solution structure of the inhibitor-free catalytic fragment of human
High-resolution solution structure of the inhibitor-free catalytic fragment of human fibroblast collagenase determined by multidimensional NMR.
Related Articles High-resolution solution structure of the inhibitor-free catalytic fragment of human fibroblast collagenase determined by multidimensional NMR.
Biochemistry. 1998 Feb 10;37(6):1495-504
Authors: Moy FJ, Chanda PK, Cosmi S, Pisano MR, Urbano C, Wilhelm J, Powers R
The high-resolution solution structure of the inhibitor-free catalytic fragment of human fibroblast collagenase (MMP-1), a...
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Solution NMR structure of the V27A drug resistant mutant of influenza A M2 channel.
Solution NMR structure of the V27A drug resistant mutant of influenza A M2 channel.
Solution NMR structure of the V27A drug resistant mutant of influenza A M2 channel.
Biochem Biophys Res Commun. 2010 Sep 9;
Authors: Pielak RM, Chou JJ
The M2 protein of influenza A virus forms a proton-selective channel that is required for viral replication; it is also the target of the anti-influenza drugs, amantadine and rimantadine. Widespread drug-resistant mutants, however, has greatly compromised the effectiveness of these drugs. Here, we report the...
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[NMR paper] NMR study on solution structure of the site-specific mutant Leu48----Ala transforming
NMR study on solution structure of the site-specific mutant Leu48----Ala transforming growth factor alpha.
Related Articles NMR study on solution structure of the site-specific mutant Leu48----Ala transforming growth factor alpha.
Int J Pept Protein Res. 1992 Feb;39(2):111-6
Authors: Kline TP, Mueller L
The NMR spectra of the Leu48----Ala mutant of human transforming growth factor alpha were compared to that of the wild-type. All chemical shift changes are less than or equal to 0.02 ppm with the exception of resonances associated with residues...