PaTrx1 and PaTrx3, two cytosolic thioredoxins of the filamentous ascomycete Podospora anserina involved in sexual development and cell degeneration

Institut de Génétique et Microbiologie, UMR CNRS - Université de Paris 11, UPS Bât. 400, 91405 Orsay cedex, France; UFR de Biochimie, Université de Paris 7 - Denis Diderot, case 7006, 2 place Jussieu, 75005, Paris, France

^* To whom correspondence should be addressed. Email: fabienne.malagnac{at}igmors.u-psud.fr.

	Abstract

In various organisms, thioredoxins are known to be involved in reduction of protein disulphide bonds and in protecting the cell from oxidative stress. Genes encoding thioredoxins were found by searching the complete genome sequence of the filamentous ascomycete Podospora anserina. Among them, PaTrx1, PaTrx2 and PaTrx3 are predicted to be canonical cytosolic proteins without additional domains. Targeted disruption of PaTrx1, PaTrx2 and PaTrx3 shows that PaTrx1 is the major thioredoxin involved in sulphur metabolism. Deletions have no effect on peroxide resistance, however data show that either PaTrx1 or PaTrx3 is necessary for sexual reproduction and for the development of the Crippled Growth cell degeneration (CG), processes that also required the PaMpk1 MAP kinase pathway. As PaTrx1 PaTrx3 mutants show not an enhancement but an impairment in CG, it seems unlikely that PaTrx1 and PaTrx3 thioredoxins participate in the inhibition of this MAP kinase pathway. Altogether these results underscore a role for thioredoxins in fungal development.