Related Experiment Videos
The oncoprotein v-Ets is less selective in DNA binding than c-Ets-1 due to the C-terminal sequence change
1LGME-CNRS and U184-INSERM, Institut de Chimie Biologique, Faculté de Médecine, Strasbourg, France.
Abstract:
The oncogene v-ets and the proto-oncogene c-ets-1 code for members of the Ets family of transcription factors that bind to DNA motifs comprising GGA(A/T) through the conserved Ets domain. c-Ets-1 and v-Ets are very similar, differing in sequence only at three positions. In this report we demonstrate that v-Ets has a less stringent target sequence requirement than c-Ets-1. v-Ets binds strongly to a broad spectrum of DNA sequence motifs, and consequently, weaker binding sites have a much greater affinity for v-Ets than c-Ets-1. c-Ets-1 carries two inhibitory domains: the D domain present N-terminal to the DNA binding domain and the C-terminal domain which is mutated in v-Ets. Our results show that the D domain has a stronger inhibitory effect than the C-terminal sequence. The on- and off-rates of c-Ets-1 vary greatly depending on the DNA binding sequences, in contrast to those of v-Ets. The c-Ets-1 on- and off-rates are higher with a strong site than with a weak site. Our data suggest that DNA sequences help c-Ets-1 change from a closed to an open, DNA-binding-competent structure, facilitating its binding to DNA, whereas v-Ets functions without such a process presumably because its different C-terminal sequence generates a constitutively open conformation. The loss of a stringent target sequence selectivity by v-Ets suggests that it might transform cells by altering expression of tightly regulated genes with non-consensus Ets binding sites.
Insights
The oncogene v-Ets protein binds DNA more broadly than the proto-oncogene c-Ets-1. This difference in DNA binding selectivity may explain how v-Ets transforms cells by affecting gene expression.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Biology
Background:
- The Ets family of transcription factors, including v-Ets and c-Ets-1, regulate gene expression by binding to specific DNA motifs.
- v-Ets is an oncogene, while c-Ets-1 is a proto-oncogene, suggesting functional differences relevant to cell transformation.
Purpose of the Study:
- To investigate the differences in DNA binding specificity and kinetics between v-Ets and c-Ets-1.
- To elucidate the structural basis for differential DNA binding and its implications for cellular transformation.
Main Methods:
- Comparative analysis of DNA binding affinities and kinetics for v-Ets and c-Ets-1 to various DNA motifs.
- Examination of the roles of inhibitory domains (D domain and C-terminal domain) in c-Ets-1 DNA binding.
Main Results:
- v-Ets exhibits broader DNA sequence recognition and higher affinity for weaker binding sites compared to c-Ets-1.
- The N-terminal D domain of c-Ets-1 exerts a stronger inhibitory effect on DNA binding than the C-terminal domain.
- DNA sequences influence c-Ets-1's transition to an active DNA-binding conformation, a process seemingly bypassed by v-Ets due to its altered C-terminus.
Conclusions:
- v-Ets's relaxed DNA binding specificity, potentially due to a constitutively open conformation, allows it to target a wider range of genes, including those with non-consensus Ets binding sites.
- This altered selectivity is a likely mechanism for v-Ets-mediated cellular transformation.