The Oct-2 glutamine-rich and proline-rich activation domains can synergize with each other or duplicates of themselves to activate transcription.

• DOI: 10.1128/mcb.14.9.6046
• Publication Date: 2012-01-24T11:22:44Z
• Authors: M Tanaka; W M Clouston; W Herr
• Keywords: Transcriptional Activation; 0301 basic medicine; 0303 health sciences; Saccharomyces cerevisiae Proteins; Base Sequence; Transcription, Genetic; Recombinant Fusion Proteins; Molecular Sequence Data; In Vitro Techniques; DNA-Binding Proteins; Fungal Proteins; Structure-Activity Relationship; 03 medical and health sciences; Gene Expression Regulation; Humans; Amino Acid Sequence; Octamer Transcription Factor-2; Oligonucleotide Probes; HeLa Cells; Transcription Factors

The B-cell POU homeodomain protein Oct-2 contains two transcriptional activation domains, one N terminal and the other C terminal of the central DNA-binding POU domain. The synergistic action of these two activation domains makes Oct-2 a more potent activator of mRNA promoters than the related broadly expressed octamer motif-binding protein Oct-1, which contains an N-terminal but not a C-terminal Oct-2-like activation domain. Both Oct-2 mRNA promoter activation domains were delineated by truncation analysis: the N-terminal Q domain is a 66-amino-acid region rich in glutamines, and the C-terminal P domain is a 42-amino-acid region rich in prolines. The Q and P domains synergized with each other or duplicates of themselves, independently of their N-terminal or C-terminal position relative to the POU domain. The C-terminal P domain, which differentiates Oct-2 from Oct-1, also activated transcription in conjunction with the heterologous GAL4 DNA-binding domain. Oct-2 thus contains three modular functional units, the DNA-binding POU domain and the two P and Q activation domains. An electrophoretic mobility shift assay with a variety of these Oct-2 activators revealed a distinct complex called QA that was dependent on the presence of an active glutamine-rich activation domain and migrated more slowly than the Oct-2-DNA complexes. Formation of the QA complex is consistent with interaction of the glutamine-rich activation domains with a regulatory protein important for the process of transcriptional activation.