The major histocompatibility complex class II promoter-binding protein RFX (NF-X) is a methylated DNA-binding protein.
A mammalian protein called RFX or NF-X binds to the X box (or X1 box) in the promoters of a number of major histocompatibility (MHC) class II genes. In this study, RFX was shown to have the same DNA-binding specificity as methylated DNA-binding protein (MDBP), and its own cDNA was found to contain a binding site for MDBP in the leader region. MDBP is a ubiquitous mammalian protein that binds to certain DNA sequences preferentially when they are CpG methylated and to other related sequences, like the X box, irrespective of DNA methylation. MDBP from HeLa and Raji cells formed DNA-protein complexes with X-box oligonucleotides that coelectrophoresed with those containing standard MDBP sites. Furthermore, MDBP and X-box oligonucleotides cross-competed for the formation of these DNA-protein complexes. DNA-protein complexes obtained with MDBP sites displayed the same partial supershifting with an antiserum directed to the N terminus of RFX seen for complexes containing an X-box oligonucleotide. Also, the in vitro-transcribed-translated product of a recombinant RFX cDNA bound specifically to MDBP ligands and displayed the DNA methylation-dependent binding of MDBP. RFX therefore contains MDBP activity and thereby also EF-C, EP, and MIF activities that are indistinguishable from MDBP and that bind to methylation-independent sites in the transcriptional enhancers of polyomavirus and hepatitis B virus and to an intron of c-myc.
Zhang
X Y
XY
Department of Biochemistry, Tulane Medical School, New Orleans, Louisiana 70112.
Jabrane-Ferrat
N
N
Asiedu
C K
CK
Samac
S
S
Peterlin
B M
BM
Ehrlich
M
M
D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D005802:Genes, MHC Class II; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D008745:Methylation; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C066141:MBD1 protein, human; D009838:Oligodeoxyribonucleotides; C000605537:RFX1 protein, human; D011994:Recombinant Proteins; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D014157:Transcription Factors