Dataset Information

Radiolysis of lac repressor by gamma-rays and heavy ions: a two-hit model for protein inactivation.

ABSTRACT: Upon gamma-ray or argon ion irradiation of the lac repressor protein, its peptide chain is cleaved and the protein loses its lac operator-binding activity, as shown respectively by polyacrylamide gel electrophoresis and retardation gel electrophoresis. We developed phenomenological models that satisfactorily account for the experimental results: the peptide chain cleavage model considers that the average number of chain breaks per protomer is proportional to the irradiation dose and that the distribution of the number of breaks per protomer obeys Poisson's law. The repressor inactivation model takes into account the quaternary structure (a dimer of dimer) and the organization of the repressor in domains (two DNA binding sites, one per dimer). A protomer is inactivated by at least two different radiation-induced damages. A dimer is inactivated when at least one of the two protomers is inactivated. A tetramer is inactivated when both dimers are inactivated. From the combination of both models, we can deduce that chain cleavage cannot account for the protein inactivation, which should mainly result from oxidation of amino acid side chains. Indeed, particularly oxidizable and accessible amino acids (Tyr, His) are involved in the DNA binding process.

SUBMITTER: Charlier M

PROVIDER: S-EPMC1302029 | biostudies-other | 2002 May

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Radiolysis of lac repressor by gamma-rays and heavy ions: a two-hit model for protein inactivation.

Charlier Michel M Eon Séverine S Sèche Edouard E Bouffard Serge S Culard Françoise F Spotheim-Maurizot Mélanie M

Biophysical journal 20020501 5

Upon gamma-ray or argon ion irradiation of the lac repressor protein, its peptide chain is cleaved and the protein loses its lac operator-binding activity, as shown respectively by polyacrylamide gel electrophoresis and retardation gel electrophoresis. We developed phenomenological models that satisfactorily account for the experimental results: the peptide chain cleavage model considers that the average number of chain breaks per protomer is proportional to the irradiation dose and that the dis ...[more]

PMID: 11964227

Similar Datasets

Project description:Space exposure experiments from the last 15 years have unexpectedly shown that several terrestrial organisms, including some multi-cellular species, are able to survive in open space without protection. The robustness of bdelloid rotifers suggests that these tiny creatures can possibly be added to the still restricted list of animals that can deal with the exposure to harsh condition of space. Bdelloids are one of the smallest animals on Earth. Living all over the world, mostly in semi-terrestrial environments, they appear to be extremely stress tolerant. Their desiccation tolerance at any stage of their life cycle is known to confer tolerance to a variety of stresses including high doses of radiation and freezing. In addition, they constitute a major scandal in evolutionary biology due to the putative absence of sexual reproduction for at least 60 million years. Adineta vaga, with its unique characteristics and a draft genome available, was selected by ESA (European Space Agency) as a model system to study extreme resistance of organisms exposed to space environment. In this manuscript, we documented the resistance of desiccated A. vaga individuals exposed to increasing doses of X-ray, protons and Fe ions. Consequences of exposure to different sources of radiation were investigated in regard to the cellular type including somatic (survival assay) and germinal cells (fertility assay). Then, the capacity of A. vaga individuals to repair DNA DSB induced by different source of radiation was investigated. Bdelloid rotifers represent a promising model in order to investigate damage induced by high or low LET radiation. The possibility of exposure both on hydrated or desiccated specimens may help to decipher contribution of direct and indirect radiation damage on biological processes. Results achieved through this study consolidate our knowledge about the radioresistance of A. vaga and improve our capacity to compare extreme resistance against radiation among living organisms including metazoan.

Dataset Information

Radiolysis of lac repressor by gamma-rays and heavy ions: a two-hit model for protein inactivation.

Publications

Radiolysis of lac repressor by gamma-rays and heavy ions: a two-hit model for protein inactivation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets