The second finger of Urbs1 is required for iron-mediated repression of sid1 in Ustilago maydis
AUTOR(ES)
An, Zhiqiang
FONTE
The National Academy of Sciences of the USA
RESUMO
The urbs1 gene encodes a transcriptional regulator of siderophore biosynthesis in Ustilago maydis. Biological and DNA-binding activities of the two putative zinc-finger motifs of Urbs1 were studied by analyzing mutants containing altered finger domains. The mutated urbs1 alleles from three previously described N′-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutants were mapped and cloned by a gap-repair procedure. Sequence analyses revealed single amino acid substitutions in two of the NTG mutants. Both mutations (G-507 to D in urbs1–1 and P-491 to L in urbs1–3), which are located in the Urbs1 C-terminal finger domain, reduced DNA-binding activity by 10-fold and were sufficient to confer a urbs1–minus phenotype. The third NTG urbs1 mutant (urbs1–2) also contained a mutation in one of the conserved amino acids (P-518 to S) in the C-terminal finger domain, but this mutation alone was not sufficient to confer a urbs1–minus phenotype. A second frame shift mutation was identified in urbs1–2 and is necessary for the urbs1–minus phenotype. In an analysis of the function of the N-terminal finger of Urbs1, the conserved amino acid Arg-350 was mutated to leucine. A Urbs1 protein with this mutation complemented a urbs1 null mutant strain. By contrast, a similar mutation in the C-terminal domain abolished the ability of Urbs1 to regulate siderophore biosynthesis and greatly reduced its ability to bind target DNA.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=20875Documentos Relacionados
- Characterization of iron-mediated peroxidative injury in isolated hepatic lysosomes.
- Nucleosomal histone protein protects DNA from iron-mediated damage.
- Iron-Mediated Control of the Basic Helix-Loop-Helix Protein FER, a Regulator of Iron Uptake in Tomato1
- Three chemically distinct types of oxidants formed by iron-mediated Fenton reactions in the presence of DNA.
- sid1, a gene initiating siderophore biosynthesis in Ustilago maydis: molecular characterization, regulation by iron, and role in phytopathogenicity.