The HMG-I(Y) A·T-hook Peptide Motif Confers DNA-binding Specificity to a Structured Chimeric Protein

Abstract

Chromosomal translocations involving genes coding for members of the HMG-I(Y) family of “high mobility group” non-histone chromatin proteins (HMG-I, HMG-Y, and HMG-IC) have been observed in numerous types of human tumors. Many of these gene rearrangements result in the creation of chimeric proteins in which the DNA-binding domains of the HMG-I(Y) proteins, the so-called A·T-hook motifs, have been fused to heterologous peptide sequences. Although little is known about either the structure or biophysical properties of these naturally occurring fusion proteins, the suggestion has been made that such chimeras have probably assumed an altered in vivoDNA-binding specificity due to the presence of the A·T-hook motifs. To investigate this possibility, we performed in vitro“domain-swap” experiments using a model protein fusion system in which a single A·T-hook peptide was exchanged for a corresponding length peptide in the well characterized “B-box” DNA-binding domain of the HMG-1 non-histone chromatin protein. Here we report that chimeric A·T-hook/B-box hybrids exhibit in vitroDNA-binding characteristics resembling those of wild type HMG-I(Y) protein, rather than the HMG-1 protein. These results strongly suggest that the chimeric fusion proteins produced in human tumors as a result of HMG-I(Y) gene chromosomal translocations also retain A·T-hook-imparted DNA-binding properties in vivo. Chromosomal translocations involving genes coding for members of the HMG-I(Y) family of “high mobility group” non-histone chromatin proteins (HMG-I, HMG-Y, and HMG-IC) have been observed in numerous types of human tumors. Many of these gene rearrangements result in the creation of chimeric proteins in which the DNA-binding domains of the HMG-I(Y) proteins, the so-called A·T-hook motifs, have been fused to heterologous peptide sequences. Although little is known about either the structure or biophysical properties of these naturally occurring fusion proteins, the suggestion has been made that such chimeras have probably assumed an altered in vivoDNA-binding specificity due to the presence of the A·T-hook motifs. To investigate this possibility, we performed in vitro“domain-swap” experiments using a model protein fusion system in which a single A·T-hook peptide was exchanged for a corresponding length peptide in the well characterized “B-box” DNA-binding domain of the HMG-1 non-histone chromatin protein. Here we report that chimeric A·T-hook/B-box hybrids exhibit in vitroDNA-binding characteristics resembling those of wild type HMG-I(Y) protein, rather than the HMG-1 protein. These results strongly suggest that the chimeric fusion proteins produced in human tumors as a result of HMG-I(Y) gene chromosomal translocations also retain A·T-hook-imparted DNA-binding properties in vivo. The mammalian HMG-I(Y) family of “high mobility group” (HMG) 1The abbreviations used are: HMG, high mobility group nonhistone chromatin proteins; aa, amino acid(s); BLT, DNA from the 3′-untranslated tail region of the bovine interleukin-2 cDNA; CD, circular dichroism; CP, nucleosome core particle; EMSA, electrophoretic mobility shift analysis; GST, glutathioneS-transferase; A·T-hook, the highly conserved DNA-binding domain of the HMG-I(Y) family of nonhistone proteins; IF, intrinsic fluorescence; NMR, nuclear magnetic resonance; PCR, polymerase chain reaction; WT, wild type; DTT, dithiothreitol; bp, base pair(s). 1The abbreviations used are: HMG, high mobility group nonhistone chromatin proteins; aa, amino acid(s); BLT, DNA from the 3′-untranslated tail region of the bovine interleukin-2 cDNA; CD, circular dichroism; CP, nucleosome core particle; EMSA, electrophoretic mobility shift analysis; GST, glutathioneS-transferase; A·T-hook, the highly conserved DNA-binding domain of the HMG-I(Y) family of nonhistone proteins; IF, intrinsic fluorescence; NMR, nuclear magnetic resonance; PCR, polymerase chain reaction; WT, wild type; DTT, dithiothreitol; bp, base pair(s). chromatin proteins are founding members of a new assemblage of nuclear proteins referred to as “architectural transcription factors,” whose role in gene regulation is the recognition and modulation of both DNA and chromatin structure (recently reviewed in Ref. 1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar). The human HMG-I(Y) protein family consists of: HMG-I (11.7 kDa), HMG-Y (10.6 kDa), and HMGI-C (12 kDa). HMG-I and HMG-Y are isoform proteins (identical in sequence except for an internal 11-amino acid deletion in the latter) derived from an alternatively spliced mRNA transcript coded for by theHMG-I(Y) gene at chromosomal locus 6p21 (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar, 2Solomon M. Strauss F. Varshavsky A. Proc. Natl. Acad. Sci. U. S. A. 1986; 83: 1276-1280Crossref PubMed Scopus (262) Google Scholar, 3Strauss F. Varshavsky A. Cell. 1984; 37: 889-901Abstract Full Text PDF PubMed Scopus (418) Google Scholar, 4Johnson K.R. Lehn D.A. Elton T.S. Barr P.J. Reeves R. J. Biol. Chem. 1988; 263: 18338-18342Abstract Full Text PDF PubMed Google Scholar, 5Johnson K.R. Lehn D.A. Reeves R. Mol. Cell. Biol. 1989; 9: 2114-2123Crossref PubMed Scopus (222) Google Scholar). The related HMGI-C protein is coded for by a separate gene located at chromosomal locus 12q14–15 (6Chau K.-Y. Patel M. Lee K.L. Lam H.-Y.P. Crane-Robinson C. Nucleic Acids Res. 1998; 23: 4262-4266Crossref Scopus (72) Google Scholar). Members of the HMG-I(Y) family share many biochemical and biophysical properties, including possessing three independent “A·T-hook” DNA-binding motifs, which exhibit a marked preference toward A·T-rich B-form DNA (2Solomon M. Strauss F. Varshavsky A. Proc. Natl. Acad. Sci. U. S. A. 1986; 83: 1276-1280Crossref PubMed Scopus (262) Google Scholar, 3Strauss F. Varshavsky A. Cell. 1984; 37: 889-901Abstract Full Text PDF PubMed Scopus (418) Google Scholar, 7Elton T.S. Nissen M.S. Reeves R. Biochem. Biophys. Res. Commun. 1987; 143: 260-265Crossref PubMed Scopus (39) Google Scholar, 8Reeves R. Nissen M.S. J. Biol. Chem. 1990; 265: 8573-8582Abstract Full Text PDF PubMed Google Scholar, 9Huth J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google Scholar). Therefore, for convenience, we will collectively refer to members of this family as simply HMG-I(Y), unless otherwise noted. Various lines of evidence indicate that the individual A·T-hook motifs of the HMG-I(Y) proteins recognize the structure associated with the narrow minor groove of A·T-rich target DNA rather than its nucleotide sequence (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar, 8Reeves R. Nissen M.S. J. Biol. Chem. 1990; 265: 8573-8582Abstract Full Text PDF PubMed Google Scholar, 10Radic M.Z. Saghbini M. Elton T.S. Reeves R. Hamkalo B. Chromosoma. 1992; 101: 602-608Crossref PubMed Scopus (67) Google Scholar,11Reeves R. Elton T.S. Nissen M.S. Lehn D. Johnson K.R. Proc. Natl. Acad. Sci. U. S. A. 1987; 84: 6531-6535Crossref PubMed Scopus (102) Google Scholar). The physical basis for this DNA-structural recognition became clear with NMR structural studies, which indicated that in the HMG-I(Y) protein is that the A·T-hook a structural for J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google Scholar, J. Nissen M.S. Reeves R. J. Res. PubMed Scopus Google Scholar). this the of the a structure that for the narrow minor groove of A·T-rich sequences. core peptide is the highly conserved peptide sequence in the HMG-I(Y) family of the A·T-hook is conserved as a DNA-binding in many proteins and transcription in from Proc. Natl. Acad. Sci. U. S. A. 1996; PubMed Scopus Google to (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar). Chromosomal translocations of the genes coding for the HMG-I(Y) proteins are the rearrangements observed in human in Ref. J. 1998; PubMed Scopus Google Scholar). the of these chromosomal translocations result in the creation of chimeric genes coding for proteins in which the A·T-hook motifs derived from of the HMG-I(Y) gene are fused to the of peptide derived from a of gene rearrangements are in human tumors including and J. 1998; PubMed Scopus Google Scholar). of chimeric proteins A·T-hook motifs. little is about these fusion in the of has been that role for these fusion in is to with the gene of the HMG-I(Y) protein M.S. A. S. Cell. Full Text PDF PubMed Scopus Google Scholar). suggestion is that a of the of the A·T-hook motifs to proteins or is to the DNA-binding characteristics of the hybrids that to new the S. Cell. 1992; Full Text PDF PubMed Scopus Google Scholar, A.M. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar). either the intrinsic is that the A·T-hook in chimeric proteins retain of in of such an is as to that the properties of the A·T-hook are altered fused to a protein human fusion protein domain amino M.S. A. S. Cell. Full Text PDF PubMed Scopus Google domains amino M.S. A. S. Cell. Full Text PDF PubMed Scopus Google amino B. S. S. J. Res. Google amino Res. 1997; Google amino B. S. S. J. J. 1998; Google amino 1998; Scopus Google amino 1996; Full Text PDF PubMed Scopus Google amino S. Reeves R. J. 1997; Google protein amino J. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google to amino J. R. S. A. B. D. Proc. Natl. Acad. Sci. U. S. A. 1997; PubMed Scopus Google amino S. Cell. 1992; Full Text PDF PubMed Scopus Google R. Cell. 1992; Full Text PDF PubMed Scopus Google of fusion proteins that the DNA are The of the genes are by a human protein. in a new of fusion proteins that the DNA are The of the genes are by a human protein. is to or the A·T-hook DNA-binding motifs in naturally occurring chimeric proteins are little is known about either the or structure of these fusion To the of the A·T-hook in the of a fusion we performed in domain experiments in which the and A·T-hook of the HMG-I(Y) protein J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google was in of a corresponding length peptide at the of the HMG-1 DNA domain (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar). The HMG-1 peptide was as a fusion for domain experiments with HMG-I(Y) NMR have that the wild type peptide is highly in Crane-Robinson C. Nucleic Acids Res. PubMed Scopus Google Scholar, P.J. J. PubMed Scopus Google and an also the of proteins that or HMG-1 DNA-binding motifs. Here we report the biophysical and properties of chimeric HMG-I(Y) of both the referred to as the and the wild type domains using circular and intrinsic a a protein, also a single A·T-hook, was and in to both the and the proteins using electrophoretic mobility shift These experiments that both the and the proteins have DNA-binding resembling those of the HMG-I(Y) proteins than those of either the HMG-1 protein or those of the HMG-1 The to the of the HMG-1 protein by with an A·T-hook DNA-binding peptide that the chimeric fusion proteins observed in in human tumors also retain the results new the of of both the HMG-1 and HMG-I(Y) A·T-hook with are as The HMG-1 corresponding to of the acid HMG-1 protein, was by of a human HMG-1 Johnson Nucleic Acids Res. 1989; PubMed Scopus Google using and The was in three The DNA region coding for the HMG-1 was the acid with and referred to as the and used to the region of the human K.R. Lehn D.A. Reeves R. Mol. Cell. Biol. 1989; 9: 2114-2123Crossref PubMed Scopus (222) Google coding for the A·T-hook DNA-binding corresponding to of the was by the DNA coding for the A·T-hook and the and the by using and The region of the corresponding to sequence to the of A·T-hook and the region of sequence to the of the nucleotide base in the base of the and HMG-1 that that amino acid coding sequence the to the The and a at the and The sequence of the was by to for of fusion The was in the as for the with The DNA coding for an HMG-1 a acid was in a of The of was by using the HMG-1 as the with and DNA coding for amino acid of the A·T-hook of the HMG-I protein corresponding to was by of human with and that this the of this peptide was from the in the HMG-I protein that to the A·T-hook of the HMG-I(Y) family of proteins R. Nissen M.S. J. Biol. Chem. 1990; 265: 8573-8582Abstract Full Text PDF PubMed Google the was by and the acid A·T-hook with the and and the region of is to the region of the A·T-hook and the region of the is to the region of the nucleotide base in the base of the that amino acid coding sequence the to The HMG-1 to of the acid HMG-1 Ref. Johnson Nucleic Acids Res. 1989; PubMed Scopus Google was by of human HMG-1 using and that DNA of the nucleotide sequence been The and the and and for of proteins as fusion and proteins and as by M. Crane-Robinson C. J. PubMed Scopus Google with to with the was at for to the for an The and was to a of to the fusion protein was with with at for The with the fusion proteins with M. Crane-Robinson C. J. PubMed Scopus Google Scholar). The was made with to and and the fusion proteins to the with at The the the protein of its was and and with the at was or fusion proteins to the The proteins from the by high The proteins and in and proteins from by the by and S. 1987; PubMed Scopus Google Scholar). to a of to of and at to and at was used to the of the protein the human HMG-I(Y) and HMG-1 proteins and as by Nissen M.S. Reeves R. J. Biol. Chem. Full Text PDF PubMed Google and by D.A. Reeves R. Nucleic Acids Res. 1997; PubMed Scopus Google The and of of the proteins by and the proteins and used for experiments to of the protein was by using from the and Biochem. 1989; PubMed Scopus Google as by the The was to for both the and and The as in Ref. Biochem. 1989; PubMed Scopus Google Scholar, is for an protein, the that in is a in the an and protein. The B-form DNA used in experiments was the well characterized 3′-untranslated tail region of the bovine interleukin-2 gene and was and used as T.S. Nissen M.S. Reeves R. Biochem. Biophys. Res. Commun. 1987; 143: 260-265Crossref PubMed Scopus (39) Google Scholar, R. Elton T.S. Nissen M.S. Lehn D. Johnson K.R. Proc. Natl. Acad. Sci. U. S. A. 1987; 84: 6531-6535Crossref PubMed Scopus (102) Google Scholar). DNA at from to to and at from to at nucleosome core of DNA as in Ref. R. Nissen M.S. J. Biol. Chem. Full Text PDF PubMed Google DNA to and at for at the in a of with protein at a of bovine DTT, and of DNA the DNA The and using M. in Scholar, R. 1996; PubMed Scopus Google Scholar). of either the or the proteins to DNA in the the and of of to of A.M. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google of DNA as in the used in the circular the of protein was at three with the used to the The of was from The was in and the and both proteins in with an of the proteins a of proteins, in DTT, used for the The was and the was from to the the HMG-1 peptide was as the fusion for a protein in which the of the has been with the A·T-hook DNA-binding peptide in the amino acid of the HMG-1 in as a structure of three and an peptide Crane-Robinson C. Nucleic Acids Res. PubMed Scopus Google P.J. J. PubMed Scopus Google Scholar). The is the region of the that is for minor groove with DNA M. Crane-Robinson C. J. PubMed Scopus Google Scholar). this peptide a sequence with the A·T-hook DNA-binding and and has three in the at and J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google Scholar, J. Nissen M.S. Reeves R. J. Res. PubMed Scopus Google Scholar). suggest that these peptide have from a sequence (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar). these in DNA-binding is that both the HMG-1 and the HMG-I(Y) proteins share to to the DNA minor to to or DNA and to to DNA such as (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar, D.A. Reeves R. Nucleic Acids Res. 1997; PubMed Scopus Google Scholar). are also a of these proteins that to both and the characteristics of an produced A·T-hook/B-box protein (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar). HMG-1 to in a the HMG-I(Y) proteins to A·T-rich the HMG-I(Y) proteins to nucleosome core R. Nissen M.S. J. Biol. Chem. Full Text PDF PubMed Google Scholar, R. 1996; PubMed Scopus Google Scholar, R. Nissen M. Prog. Res. the HMG-1 protein to the DNA in chromatin (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar). and proteins both as fusion and The and proteins as fusion proteins, which by with to the To the of and the of the and proteins with a in the and proteins have in amino acid at and to the and and both the and proteins are amino in length and both of these proteins, amino the and the are derived from the The proteins are in length at amino have a of these minor the proteins biophysical properties and also in that in amino acid have properties that biophysical that are observed the and the are due to in the of of peptide domains and are to of an for the proteins, the that with the to its The in this as with the are that have been at the of the A·T-hook and that both a and a highly conserved D. Nucleic Acids Res. PubMed Scopus Google and in The of these in to the region of the the and of the protein. structural was by structural the of structure in a and was used to that both the and the proteins structural the structural of the in the at for both the and proteins derived from fusion those for M. Crane-Robinson C. J. PubMed Scopus Google Scholar, J. PubMed Scopus Google Scholar). The Johnson Biochem. 1986; PubMed Scopus Google to of and for the and proteins are to and also that to the for both proteins shift toward a of an or The protein was also using at both and and is to the and proteins derived from fusion these indicate that three of these proteins have at and of a domain Crane-Robinson C. Nucleic Acids Res. PubMed Scopus Google Scholar, P.J. J. PubMed Scopus Google Scholar, M. Crane-Robinson C. J. PubMed Scopus Google Scholar). The in the of the for the and the proteins at both and and are to in and The intrinsic in that the of the and the proteins are These indicate that the in the of these three are from the for three of the proteins are also and an to and the peptide region the a the structure of the chimeric the result a marked in the of the derived from fusion to that of the in and this is the Therefore, both the and we the and both of the proteins are a structure of a HMG-1 protein. to the for the proteins the at for the protein is to the of proteins at with this the for the is from that of The a shift of for the and a in the of to the three proteins with the the indicate that the is structural to the as the or These also that the physical characteristics resembling those of rather than a of proteins to a well characterized A·T-rich DNA BLT, the 3′-untranslated tail region of the bovine interleukin-2 T.S. Nissen M.S. Reeves R. Biochem. Biophys. Res. Commun. 1987; 143: 260-265Crossref PubMed Scopus (39) Google Scholar, R. Elton T.S. Nissen M.S. Lehn D. Johnson K.R. Proc. Natl. Acad. Sci. U. S. A. 1987; 84: 6531-6535Crossref PubMed Scopus (102) Google Scholar). HMG-I(Y) is known to to the A·T-rich of the both the HMG-1 protein and to B-form DNA that the HMG-I(Y) protein a of with DNA as a of of protein. both the HMG-1 protein and the to the as by the of the in both this that the in the and of are rather are in and the the a of of the by the is that the protein in are from the by either the HMG-1 or the that are of in the of HMG-I(Y) and the protein for in is at by the of DNA-binding motifs in the the HMG-I(Y) protein, which has three independent A·T-hook motifs that with A·T-rich R. Nissen M.S. J. Biol. Chem. 1990; 265: 8573-8582Abstract Full Text PDF PubMed Google Scholar, 9Huth J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google DNA in the the protein, which has a single A·T-hook and has a for this R. Nissen M.S. J. Biol. Chem. 1990; 265: 8573-8582Abstract Full Text PDF PubMed Google in the of the A·T-hook in the of the to the of the J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google Scholar). with this the as in also with DNA at a the than the is that the A·T-hook in the is by a structural and is to the in the HMG-I(Y) protein J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google Scholar). both proteins are to that the to to A·T-rich has been to the fusion proteins by the A·T-hook DNA these that the A·T-hook peptide structure is by the presence of the structural of the HMG-1 in the protein. of DNA experiments performed to by an independent that the protein is the narrow minor groove structure associated with of A·T-rich the results of experiments in which the protein was with DNA in the presence of of of DNA a or a for A·T-rich DNA sequences. in and the is to DNA is of as in in the presence of of these are and is to both a and the DNA the as with at of the is also the in of that with for are observed for the of these is the that has been to with the HMG-I(Y) protein for to the A·T-rich in DNA and R. Nissen M.S. J. Biol. Chem. 1990; 265: 8573-8582Abstract Full Text PDF PubMed Google M.Z. Saghbini M. Elton T.S. Reeves R. Hamkalo B. Chromosoma. 1992; 101: 602-608Crossref PubMed Scopus (67) Google Scholar). C. B. and R. These results suggest that the protein the structural characteristics of a narrow minor groove such as that associated with A·T-rich the results of experiments in which a was made the of by the of the protein and the protein A·T-rich indicated by the lines to the in the protein of A·T-rich in to the of DNA in the the protein of the to the the of for the protein to these A·T-rich in the DNA is to the for the HMG-I(Y) protein this T.S. Nissen M.S. Reeves R. Biochem. Biophys. Res. Commun. 1987; 143: 260-265Crossref PubMed Scopus (39) Google Scholar, R. Elton T.S. Nissen M.S. Lehn D. Johnson K.R. Proc. Natl. Acad. Sci. U. S. A. 1987; 84: 6531-6535Crossref PubMed Scopus (102) Google Scholar). These with the results from the and that the specificity of the protein has been altered to that of the HMG-I(Y) protein for A·T-rich of B-form is well in the HMG-1 protein to the DNA region in to nucleosome core that DNA (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google Scholar). marked as in HMG-I(Y) to or with the sequence nucleosome core from These are with R. Nissen M.S. J. Biol. Chem. Full Text PDF PubMed Google and are to a of the A·T-hook motifs of the HMG-I(Y) protein structural of the DNA as the R. Nissen M.S. J. Biol. Chem. Full Text PDF PubMed Google Scholar, R. 1996; PubMed Scopus Google Scholar). a as indicated by the in the also a of with nucleosome core with a to the HMG-I(Y) protein this core is a of a single A·T-hook peptide sequence in the protein with a of this peptide is the highly HMG-1 the HMG-1 protein the peptide to nucleosome core these these that the single A·T-hook in the protein has chromatin properties to the chimeric protein. to chromosomal of A·T-hook DNA-binding motifs J. 1998; PubMed Scopus Google of the genes coding for the HMG-I(Y) family of nonhistone chromatin proteins has also been associated with a of types in and the that the HMG-I(Y) proteins of gene (1Bustin M. Reeves R. Prog. Nucleic Acid Res. Mol. Biol. 1996; 54: 35-100Crossref PubMed Google and also are in regulation M. Reeves R. Nucleic Acids Res. PubMed Scopus Google Scholar, A. D. Mol. Cell. Biol. 1992; PubMed Scopus Google Scholar, PubMed Scopus Google as that or chromosomal of the DNA-binding of the HMG-I(Y) genes to such as and is the by the HMG-I(Y) proteins, or in these the by the chimeric fusion proteins associated with a of tumors and experiments in a well characterized in model protein we have that the A·T-hook of the HMG-I(Y) protein family its and its nucleosome core specificity in both an protein and in a protein. These are strongly suggest that chimeric proteins retain many of the properties of the HMG-I(Y) protein of or these hybrids are in a Although the structural characteristics of the peptide fused to are to the specificity of the A·T-hook motifs in the of the proteins for The of characteristics to chimeric proteins in a for the of a new of at such The results also about the structural of both the and the A·T-hook that the fusion of these to a chimeric protein, the has the structure of the of the HMG-1 protein family and the the specificity of the HMG-I(Y) protein this from of the known of both the and A·T-hook as either in J. Nissen M.S. Reeves R. J. Res. PubMed Scopus Google Scholar, Crane-Robinson C. Nucleic Acids Res. PubMed Scopus Google Scholar, P.J. J. PubMed Scopus Google Scholar, PubMed Scopus Google or as with DNA J.R. Bewley C.A. Nissen M.S. Evans J.N. Reeves R. Gronenborn A.M. Clore G.M. Nat. Struct. Biol. 1997; 4: 657-665Crossref PubMed Scopus (303) Google Scholar, J.R. Gronenborn A.M. Clore G.M. Cell. Full Text PDF PubMed Scopus Google Scholar). NMR of a of the DNA-binding domains of HMG-I(Y) with a indicate that the A·T-hook a structural that is for with the minor groove of A·T-rich sequences. by the results the of the A·T-hook in the peptide region of the is to this structural that in the both the peptide and the of the in the sequence of the A·T-hook the physical for with the minor groove of the specificity the chimeric protein the also that the peptide and the of the and in the domain of the Crane-Robinson C. Nucleic Acids Res. PubMed Scopus Google are to such a physical the of the to to these results a structural for the these otherwise are numerous from the with to the and of human tumors associated with chromosomal translocations involving the A·T-hook The and of these is that many of the chimeric fusion proteins probably have DNA and nucleosome properties in an by made with the A·T-hook motifs of the gene A.M. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). as the results are with the that these fusion proteins have also properties that are for in of the HMG-I(Y) these properties of the chimeric proteins are: of the high of the A·T-hook motifs to A·T-rich DNA of of the of a of of the gene to the of the of the of the protein to with proteins, of for biochemical in the of of the in the of the proteins, as well as of otherwise fusion proteins to to gene as well as in chromatin in as to the in by these chimeric proteins to the type of protein fused to the A·T-hook in the of these proteins the of A·T-hook motifs related to the A·T-hook such as of of proteins are to at as as the of the fusion of the structure and DNA-binding properties of individual chimeric proteins in tumors the role and of the A·T-hook in and A. for of circular Nissen for and for the of used in