Ahp1 e Tsa1 de Saccharomyces cerevisiae: regulação gênica, caracterização bioquímica, estrutura e função das duas peroxirredoxinas mais abundantes de leveduras / Saccharomyces cerevisiae Ahp1 and Tsa1: transcriptional regulation, biochemical characterization, structure and function of the two most abundant peroxiredoxins from yeast.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The incomplete reduction of oxygen to water during respiration results in the formation of Reactive Oxygen Species (ROS), oxidizing compounds, which can generate severe cellular oxidative stress. Aerobic cells are equipped with a complex defense system to cope with this condition. Peroxiredoxins make up a family of antioxidant enzymes with the ability to remove hydroperoxides at the expense of a thiol-containing reducing agent, thereby protecting biomolecules from oxidative damage. Ahp1 and Tsa1 are the two most abundant peroxiredoxins in the yeast Saccharomyces cerevisiae, each one making up to 1% of the cellular soluble proteins. In this work, we carried out a biochemical characterization of some of Ahp1s properties, particularly of its substrate preferences and sensitivity to inactivation by hydroperoxides, which have been compared to those of Tsa1. In one approach, Ahp1 crystals were obtained and diffracted at 1.8A resolution. Several methods were unsuccessfully employed in the attempt to solve Ahp1 structure. On the other hand, the three-dimensional structure of Tsa1 was solved, aiming to correlate its functional properties with its spatial organization. In another part of the work, relations between the regulation of AHP1 and other Prx genes were revealed. Ahp1, together with Tsa2 and Prx1, appears to carry out an important role in the cellular defense against oxidative stress, in conditions where peroxisomes are active and devoid of catalase.

ASSUNTO(S)

tsa1 peroxirredoxinas tsa1 ahp1 leveduras peroxiredoxins yeast estresse oxidativo oxidative stress ahp1

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