title: The Cys4 zinc finger of bacteriophage T7 primase in sequence-specific single-stranded DNA recognition.
abstract: Bacteriophage T7 DNA primase recognizes 5'-GTC-3' in single-stranded DNA. The primase contains a single Cys4 zinc-binding motif that is essential for recognition. Biochemical and mutagenic analyses suggest that the Cys4 motif contacts cytosine of 5'-GTC-3' and may also contribute to thymine recognition. Residues His33 and Asp31 are critical for these interactions. Biochemical analysis also reveals that T7 primase selectively binds CTP in the absence of DNA. We propose that bound CTP selects the remaining base G, of 5'-GTC-3', by base pairing. Our deduced mechanism for recognition of ssDNA by Cys4 motifs bears little resemblance to the recognition of trinucleotides of double-stranded DNA by Cys2His2 zinc fingers.
authors: Department of Biological Chemistry and Molecular Pharmacology, Harvard University Medical School, Boston, MA 02115, USA.
authors: T
authors: T
authors: Kusakabe
authors: A V
authors: AV
authors: Hine
authors: S G
authors: SG
authors: Hyberts
authors: C C
authors: CC
authors: Richardson
mesh_terms: D017123:Bacteriophage T7 / Q000201:enzymology; D001483:Base Sequence; D001665:Binding Sites; D003545:Cysteine; D019915:DNA Primase / Q000737:chemistry* / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013941:Thymine; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism; D035165:Transcription Factors, General; D035602:Transcriptional Elongation Factors; D016335:Zinc Fingers
chemical_list: D004277:DNA, Single-Stranded; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D014157:Transcription Factors; D035165:Transcription Factors, General; D035602:Transcriptional Elongation Factors; C018648:transcription factor S-II; D019915:DNA Primase; D003545:Cysteine; D013941:Thymine