eEF1A Controls Ascospore Differentiation Through Elevated Accuracy, but Controls Longevity and Fruiting Body Formation Through Another Mechanism in Podospora anserina

Corresponding author: Philippe Silar, Institut de Génétique et Microbiologie de l'Université de Paris Sud, C.N.R.S. UMR 8621, Bât. 400, 91405 Orsay Cedex, France., silar{at}igmors.u-psud.fr (E-mail)

Communicating editor: S. SANDMEYER

Antisuppressor mutations in the eEF1A gene of Podospora anserina were previously shown to impair ascospore formation, to drastically increase life span, and to permit the development of the Crippled Growth degenerative process. Here, we show that eEF1A controls ascospore formation through accuracy level maintenance. Examination of antisuppressor mutant perithecia reveals two main cytological defects, mislocalization of spindle and nuclei and nuclear death. Antisuppression levels are shown to be highly dependent upon both the mutation site and the suppressor used, precluding any correlation between antisuppression efficiency and severity of the sporulation impairment. Nevertheless, severity of ascospore differentiation defect is correlated with resistance to paromomycin. We also show that eEF1A controls fruiting body formation and longevity through a mechanism(s) different from accuracy control. In vivo, GFP tagging of the protein in a way that partly retains its function confirmed earlier cytological observation; i.e., this factor is mainly diffuse within the cytosol, but may transiently accumulate within nuclei or in defined regions of the cytoplasm. These data emphasize the fact that the translation apparatus exerts a global regulatory control over cell physiology and that eEF1A is one of the key factors involved in this monitoring.