Roles in dimerization and blue light photoresponse of the PAS and LOV domains of Neurospora crassa white collar proteins.
The genes coding for white collar-1 and white collar-2 (wc-1 and wc-2) have been isolated previously, and their products characterized as Zn-finger transcription factors involved in the control of blue light-induced genes. Here, we show that the PAS dimerization domains present in both proteins enable the WC-1 and WC-2 proteins to dimerize in vitro. Homodimers and heterodimers are formed between the white collar (WC) proteins. A computer analysis of WC-1 reveals a second domain, called LOV, also identified in NPH1, a putative blue light photoreceptor in plants and conserved in redox-sensitive proteins and in the phytochromes. The WC-1 LOV domain does not dimerize with canonical PAS domains, but it is able to self-dimerize. The isolation of three blind wc-1 strains, each with a single amino acid substitution only in the LOV domain, reveals that this region is essential for blue light responses in Neurospora. The demonstration that the WC-1 proteins in these LOV mutants are still able to self-dimerize suggests that this domain plays an additional role, essential in blue light signal transduction.
Ballario
P
P
Dipartimento di Genetica e Biologia Molecolare, Centro di Studio per gli Acidi Nucleici, Università di Roma La Sapienza, Rome, Italy.
Talora
C
C
Galli
D
D
Linden
H
H
Macino
G
G
D000595:Amino Acid Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D019281:Dimerization; D005656:Fungal Proteins; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation; D009492:Neurospora crassa / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D014157:Transcription Factors; C105589:wc-1 protein, Neurospora crassa; C103772:white collar 2 protein, Neurospora