Research

Prof. Dr. Klaus Grasser - Research

In eukaryotic cells, the large genomic DNA is packaged with histones and other proteins into chromatin. The compaction of the DNA provided by chromatin generally represses DNA-dependent processes such as the transcription of genes. During transcriptional elongation so-called transcript elongation factors facilitate transcript synthesis catalysed by RNA polymerase II. Using the Arabidopsis model system, we examine how these factors are involved in gene expression, development and plant responses to changing environmental conditions. In addition we are interested in the interplay with co-transcriptional mRNA processing and the mechanism of the nucleo-cytosolic transport of mRNAs. Towards these goals we employ approaches from the fields of molecular and cellular biology as well as biochemistry and genetics.

Transcript elongation factors

Transcript elongation by RNA polymerase II (RNAPII), once regarded as the simple extension of the initiated mRNA, is a complex and highly regulated phase of the transcription cycle. Many factors have been identified that contribute to the dynamic control of the elongation stage of transcription. There are transcript elongation factors (TEFs) that modulate the activity of RNAPII (green symbols in the scheme), while others facilitate the transcription through chromatin (blue and orange symbols), or covalently modify nucleosomal histones (i.e. methylation, acetylation, ubiquitination) within the transcribed regions (yellow symbols) (Van Lijsebettens and Grasser, 2014). Several TEFs including TFIIS, FACT, SPT4/SPT5 and PAF1C were found to associate with the elongating RNAPII (S2P, S5P phosphorylated) forming the transcript elongation complex (Antosz et al., 2017).

Tec Scheme 2014

The Arabidopsis FACT (facilitates chromatin transcription) complex is composed of the SSRP1 and the SPT16 proteins and localises to the transcriptionally active euchromatin of the majority of cell types. T