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Selective inhibition of c-Myb DNA-binding by RNA polymers.

2004; BioMed Central; Volume: 5; Issue: 1 Linguagem: Inglês

10.1186/1471-2091-5-15

1471-2091

Oddmund Nordgård, Tor Øyvind Andersen, Odd S. Gabrielsen,

Genomics and Chromatin Dynamics

Abstract Background The transcription factor c-Myb is expressed in hematopoietic progenitor cells and other rapidly proliferating tissues, regulating genes important for proliferation, differentiation and survival. The DNA-binding domain (DBD) of c-Myb contains three tandemly arranged imperfect repeats, designated Myb domain R 1 , R 2 and R 3 . The three-dimensional structure of the DBD shows that only the second and third Myb domains are directly involved in sequence-specific DNA-binding, while the R 1 repeat does not contact DNA and only marginally affects DNA-binding properties. No structural information is available on the N-terminal 30 residues. Since deletion of the N-terminal region including R 1 plays an important role in oncogenic activation of c-Myb, we asked whether this region confers properties beyond DNA-binding to the neighbouring c-Myb DBD. Results Analysis of a putative RNA-binding function of c-Myb DBD revealed that poly(G) preferentially inhibited c-Myb DNA-binding. A strong sequence-selectivity was observed when different RNA polymers were compared. Most interesting, the poly(G) sensitivity was significantly larger for a protein containing the N-terminus and the R 1 -repeat than for the minimal DNA-binding domain. Conclusion Preferential inhibition of c-Myb DNA binding by poly(G) RNA suggests that c-Myb is able to interact with RNA in a sequence-selective manner. While R 2 and R 3 , but not R 1 , are necessary for DNA-binding, R 1 seems to have a distinct role in enhancing the RNA-sensitivity of c-Myb.