A rolB regulatory factor belongs to a new class of single zinc finger plant proteins.
A protein which binds to the regulatory domain B necessary for expression of the plant oncogene rolB in (root) meristems contains a single zinc finger of a novel type conserved in dicots and monocots. Band shift analysis revealed the presence in tobacco nuclei of a protein selectively binding to domain B, a tetramer of which was used to isolate a cDNA (NtBBF1, Nicotiana tabacum rolB domain B Factor 1) from a tobacco expression library. The corresponding genomic clone was also isolated. The protein encoded by NtBBF1 contains a single C2C2 zinc finger, and its target sequence in domain B was identified by means of mutagenized oligonucleotides. The DNA-binding capability of the zinc finger was assessed by means of a fusion of this latter with the glutathione-S-transferase protein, that was shown to bind the same target sequence as NtBBF1. A number of other tobacco cDNAs encoding different proteins with a domain (BBF domain) encompassing the zinc finger identical to NtBBF1 were also isolated. Furthermore, a cDNA encoding a protein with an almost identical single zinc finger was isolated from Arabidopsis. A very closely related zinc finger has very recently been identified in maize transcription factors and termed the Dof domain. It is proposed that the tobacco, Arabidopsis and maize BBF/Dof domain proteins are members of a new broad family of plant transcription factors acting through a single zinc finger widely utilized in the plant kingdom.
De Paolis
A
A
Istituto Pasteur Fondazione Cenci Bolognetti, Dip. Genetica e Biologia Molecolare, Università di Roma La Sapienza, Italy.
Sabatini
S
S
De Pascalis
L
L
Costantino
P
P
Capone
I
I
D000595:Amino Acid Sequence; D001483:Base Sequence; D017124:Conserved Sequence; D018076:DNA, Complementary / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D018745:Genome, Plant; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*; D010947:Plants, Toxic; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D016335:Zinc Fingers
C118814:BBF1 protein, Nicotiana tabacum; D018076:DNA, Complementary; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D014157:Transcription Factors