The Role of AHA Motifs in the Activator Function of Tomato Heat Stress Transcription Factors HsfA1 and HsfA2

Citations Over TimeTop 18% of 2000 papers

Abstract

Using reporter assays in tobacco protoplasts and yeast, we investigated the function of the acidic C-terminal activation domains of tomato heat stress transcription factors HsfA1 and HsfA2. Both transcription factors contain short, essential peptide motifs with a characteristic pattern of aromatic and large hydrophobic amino acid residues embedded in an acidic context (AHA motifs). The prototype is the AHA1 motif of HsfA2, which has the sequence DDIWEELL. Our mutational analysis supports the important role of the aromatic and large hydrophobic amino acid residues in the core positions of the AHA motifs. The pattern suggests the formation of an amphipathic, negatively charged helix as the putative contact region with components of the basal transcription complex. In support of this concept, proline or positively charged residues in or adjacent to the AHA motifs markedly reduce or abolish their activity. Both AHA motifs of HsfA1 and HsfA2 contribute to activator potential, and they can substitute for each other; however, there is evidence for sequence and positional specificity.

Related Papers

• → RNA structural motifs: building blocks of a modular biomolecule(2005)217 cited
• → The fragment transformation method to detect the protein structural motifs(2006)23 cited
• → Sequence motifs of myelin membrane proteins: Towards the molecular basis of diseases(2013)8 cited
• → Construction of a dictionary of sequence motifs that characterize groups of related proteins(1992)44 cited
• → Computational approaches, databases and tools for in silico motif discovery(2012)1 cited