Identification of a human T-cell leukemia virus type I tax peptide in contact with DNA.
The human T-cell leukemia virus Tax protein directs binding of a host factor, cAMP response element binding protein, to an extended recognition sequence in the proviral promoter. Prior cross-linking experiments have revealed that Tax makes restricted contact with this DNA at two symmetric positions, 14 nucleotides apart on opposite strands of the DNA. Tax lacks a conventional DNA binding domain, and the sequences in Tax that are in contact with DNA have not been previously identified. Analysis of cross-linked peptides now shows that the contact occurs between Tax residues 89 and 110, corresponding to a protease-sensitive linker joining two protein structural domains. The linker assumes a protease-resistant conformation in the cross-linked complex. Point mutations within the linker prevent cross-linking and interfere with Tax function. These data suggest that entry of Tax into the ternary complex may be coupled to folding of an unstructured protein domain, which then makes base-specific contacts with DNA.
Kimzey
A L
AL
Gene Regulation Program, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, Georgia 30912, USA.
Dynan
W S
WS
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D003432:Cross-Linking Reagents / Q000737:chemistry; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D016356:Gene Products, tax / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015368:Human T-lymphotropic virus 1 / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015345:Oligonucleotide Probes; D017354:Point Mutation; D011485:Protein Binding; D015533:Transcriptional Activation
D003432:Cross-Linking Reagents; D017362:Cyclic AMP Response Element-Binding Protein; D016356:Gene Products, tax; D015345:Oligonucleotide Probes; D004247:DNA