Promoters and their regulation in Ustilago maydis and other phytopathogenic fungi.

The lifestyle of phytopathogenic fungi is strongly determined by their environment. This implies that mechanisms providing for versatile gene regulation in response to external signals or during host associations exist. In Ustilago maydis, central players of pathogenic development are the high mobility group box protein Prf1 that binds to the pheromone response element and the homeodomain transcription factor b, which recognizes an hsg-like consensus motif known from yeast Mata1-Matalpha2 DNA binding. Transcription of prf1 is influenced by multiple inputs and this is reflected by its modular promoter structure. Analysis of the U. maydis mig promoters provides a link to transcriptional regulation during biotrophic growth. Furthermore, recognition of repeated GATA sequences as well as of triplet motifs by transcription factors with binuclear Zn(II)(2)Cys(6) DNA-binding domains appears to mediate diverse transcriptional responses relevant for phytopathogenic fungi. Although present studies shed some light on the complexity of transcriptional processes operating in phytopathogenic fungi, further investigation of promoter structures including the involvement of ubiquitous promoter elements is needed. Confronted with increasing genome-wide analysis, knowledge of promoter structures not only allows predicting transcriptional regulation, but might also advance our understanding of transcriptional networks.