Effects of the Cobalt-60 gamma radiation on Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase

Abstract

Purpose

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a key enzyme of the glycolytic pathway, can play a physiological regulatory role and vital other roles in metabolism. This study investigated the effects of gamma radiation generated by Cobalt-60 source on GAPDH activity and protein levels in Pichia pastoris as an eukaryotic organism model.

Materials and methods

After purification of the GAPDH from P. pastoris, in vitro effects of irradiation to the dose of 2 Gy, using Cobalt-60 at the dose rate of 0.25 Gy/min, on activity and kinetic parameters were investigated. In vivo effects of gamma exposition (dose of 5 Gy) on P. pastoris GAPDH and on reactive oxygen species (ROS) markers were also explored.

Results and conclusions

The in vitro irradiation of the purified GAPDH reduces the specific activity and the maximum velocity (V_max) without alteration of substrates binding (K_m). No changes occurred in the specific activity and in kinetic parameters when P. pastoris cells were exposed to Cobalt-60 source. However, this in vivo irradiation of cells produced a significant increase of the GAPDH protein level. The changes of GAPDH activity and the increase of the enzyme population as a target for gamma radiation exposure will play a role in cells adaptation under stress conditions. On the other hand, the increase of malondialdehyde and carbonyl contents and the enhancement of catalase and superoxide dismutase in irradiated cells have been noticed. The antioxidant system can play an important role in the protection of P. pastoris GAPDH against the gamma induced-ROS damage. This is the first report of the P. pastoris GAPDH as a physiological target of gamma exposition.

Keywords:

• Cobalt-60 source
• gamma radiation
• Pichia pastoris
• glyceraldehyde-3-phosphate dehydrogenase
• oxidative damage
• antioxidant biomarkers

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Center for Nuclear Energy, Science and Technology (CNESTEN) as an internal project grant.

Notes on contributors

Abdelghani Iddar

Abdelghani Iddar is a Researcher and a Research Projects Manager at Biotechnology and Engineering of Biomolecules Unit, National Center for Nuclear Energy, Science and Technology, Rabat, Morocco. He has obtained his PhD Biochemistry and Molecular Biology at the Hassan II University, Casablanca, Morocco in collaboration with the Institute of Plant Biochemistry and Photosynthesis, Seville, Spain and supported by AECI, Spain (2002).

Mohammed El Mzibri

Mohammed El Mzibri is the Head of the Life Science Division, National Center for Nuclear Energy, Science and Technology, Rabat, Morocco and the coordinator of the Joint Research Unit Nutrition and Alimentation (Ibn Tofaïl University, Kenitra, Morocco). He has obtained his PhD Molecular Biology at the Mediterranean University, Marseilles, France (1996).

Adnane Moutaouakkil

Adnane Moutaouakkil is a Researcher and a Research Projects Manager at Biotechnology and Engineering of Biomolecules Unit, National Center for Nuclear Energy, Science and Technology, Rabat, Morocco. He has obtained his PhD Microbiology and Biotechnology at the Hassan II University, Casablanca, Morocco in collaboration with the Louis Pasteur University, Strasbourg, France (2004).