Figure 4.

Transcriptional regulation of genes encoding proteins with a role in protein folding and secretion in P. pastoris grown at different specific growth rates in glucose-limited chemostat cultures. (A) Genes related to the secretory pathway that were at least at one growth rate setpoint differentially expressed (adjusted p-value < 0.02, see Section 2) when compared to the highest μ of 0.15 h^–1 were grouped into six clusters using the k-means clustering algorithm. Relative expression levels (log2 scale, y-axis) are displayed for each gene at the different growth rate setpoints (x-axis) as well as the mean FC (magenta line). For every growth rate setpoint samples were collected from three individual cultivations and microarray experiments were performed in 2-color technical duplicates for every sample. (B) Genes of the clusters in (A) were mapped on the secretory pathway, using the color code of the clusters. For genes without a homolog in S. cerevisiae or a different yeast, the P. pastoris GS115 ORF number was assigned. If P. pastoris contained more than one ortholog, a number was added, e.g. MNN4-1, MNN4-2. (C) Overview of total numbers of genes allocated to different biological processes related to the secretory pathway, and relative numbers of regulated genes. Color intensities reflect the degree of regulation of the respective groups.