Xiang, Q., Kim, K. S., Roy, S., and Judelson, H. S. 2009. A motif within a complex promoter from the oomycete Phytophthora infestans determines transcription during an intermediate stage of sporulation. Fungal Genetics and Biology, in press

Sporulation in Phytophthora infestans is associated with a major remodeling of the transcriptome. To better understand promoter structure and how sporulation-specific expression is determined in this organism, the Pks1 gene was analyzed. Pks1 encodes a protein kinase that is induced at an intermediate stage of sporulation, prior to sporangium maturation. Major and minor transcription start sites mapped throughout the promoter, which contains many T-rich stretches and Inr-like elements. Within the T-rich region are several motifs which bound nuclear proteins in EMSA. Tests of modified promoters in transformants implicated a CCGTTG located 110-nt upstream of the transcription start point as a major regulator of sporulation-specific transcription. The motif also bound a sporulation-specific nuclear protein complex. A bioinformatics analysis indicated that the motif is highly over-represented within co-expressed promoters, in which it predominantly resides 100 to 300-nt upstream of transcription start sites. Other sequences, such as a CATTTGTT motif, also bound nuclear proteins but did not play an essential role in spore-specific expression.