Program Book - 27th Fungal Genetics Conference

PLENARY SESSION ABSTRACTSof nuclei, remains a mystery. However, recent studies of the mitotic NIMA kinase indicates it plays additional non-mitotic cytoplasmic functions inAspergillus nidulans that impinge on fungal development. These insights were derived initially from defining the interphase subcellular locations of NIMAwhich revealed it locates to both forming and mature septa and additionally locates to tips of growing interphase cells. Subsequent studies revealed thatseptal pores are subject to cell cycle regulation which prevents cytoplasmic movement between mitotic cell compartments and their adjacent interphasepartners. We further find that NIMA markedly affects the regulation of cell tip dominance and morphology via a mechanism involving NIMA location atmicrotubule +ends and the modulation of interphase cytoskeletal functions. Collectively the findings indicate that the mitotic NIMA kinase has roles toregulate communication between adjacent hyphal cells as well as cytoskeletal functions important for normal tip cell growth. Thus NIMA has the potentialto help integrate nuclear division with cell division and morphogenesis.A Neurospora cell-free system reconstitutes peroxisome membrane protein synthesis and organelle-specific targeting. Gregory Jedd. Temasek LifeSciences Laboratory, Singapore, Singapore.A central problem faced by eukaryotic cells is how to ensure that membrane proteins are localized to the appropriate organelle. Peroxisomes areubiquitous eukaryotic organelles that proliferate through growth and division, and can also arise de novo from endoplasmic reticulum (ER)-derivedprecursors. Two distinct views for the biogenesis of peroxisome membrane proteins (PMPs) are currently entertained. In the direct targeting model, PEX19recognizes PMPs in the cytosol and ferries them to the peroxisome where interaction with PEX3 prompts PMP release and membrane integration. In thesecond model, nascent PMPs are integrated to the ER membrane first, and then traffic to the peroxisome membrane. In this case, PEX19 functions as asorting receptor to package PMPs into ER-derived vesicles. My talk will focus on development of a cell-free system that reconstitutes PMP synthesis andtargeting to the peroxisome membrane. I will discuss how distinct chaperones and sequences associated with transmembrane domains distinguish directER and peroxisome targeting pathways.26