The differential expression of key elements of the UPR, such as homologs of p58IPK and Gcn4p (CpcA), suggests that upregulation of the secretory pathway on maltose occurs via Gcn4p-independent mechanisms.
In this category is AFUA_4G12470 (CpcA) a transcription factor that is required for the cross-pathway control, a mechanism that provides amino acid supply during amino acid starvation by increasing the synthesis of biosynthetic genes.
However, the mRNA accumulation level of cpcBA, the first two genes in the operon, was clearly higher in the wild type than for cpcC2C1D, suggesting possible regulation by imperfect termination of transcription 3′ to cpcA.
In our transcriptomic profiles, a gcn2 homologue (An17g00860) is not differentially expressed, whereas cpcA (An01g07900) shows ≈ 2 fold higher expression in comparison with the wild-type strain.
For example, PCA and structural equation modelling (SEM; [23]) can be used to examine how immune indices are correlated within a single group, and common principal components analysis (CPCA; [24], [25]) can be used to examine whether indices correlate in the same way among multiple groups.
Besides a reduction in the expression of the protein synthesis machinery, also the components of the phycobilisome light harvesting complex, including the structural genes CpcA, CpcB, CpcC1, CpcC2, and CpcG2 (Sll1471), as well as PbsA1 (heme oxygenase 1), HemE and HemF [i.e. the latter three all involved in chromophore (tetrapyrrole) biosynthesis], were decreased in relative abundance.
In our study, CpcA (An01g07900), a homolog of Gcn4p, was down-regulated on maltose, much in contradiction with its putative function as positive regulator of transcription of several UPR target genes in the secretory pathway.
The upstream and downstream fragments of cpcA (ATEG_03131) were amplified from gDNA of A. terreus SBUG844 using oligonucleotides P53/54 (943 bp) and P55/56 (853 bp).
Algorithm 1 Categorical PCA (CPCA) Initialize with, and by random values.
The signal from CpcC is transmitted to the transcription factor CpcA (An01g07900) (homologue of S. cerevisiae Gcn4p), a global regulator in A. niger induced by amino acid starvation.
put forward the characteristics scoring method of the multivariate time sequence on the basis of the correlation between information according to the common principal component analysis (CPCA) [24].
