Binding Proteins and Activates Development When Overexpressed

Overexpression of several different Aspergillus niduluns developmental regulatory genes has been shown to cause inappropriate developmental activation and growth inhibition. We previously exploited this observation that induced development caused growth inhibition in designing a screen to identify other genes that could activate development when overexpressed. We identified 16 mutants in which induced expression of different random genomic DNA sequences caused growth inhibition, accumulation of mRNA corresponding to the brk4 developmental regulatory locus, and in several cases sporulation. This phenotype was designated FAB for Forced expression Activation of brD1. and the genes were called fabA through fabP. Here we describe one of these genes, fabM, which is predicted to encode a poly(A)binding protein (PABP) that is constitutively expressed and is essential for viability. While it is unclear why overexpression of the fabM caused sporulation, we showed that this activity required other known early developmental regulators including JbA, JbB, JbC, and JUG. We propose that fabM is an example of a gene that is not only required for growth, but also has specific functions early in development that assist developmental induction, presumably by allowing translation of specific mRNAs like