Biology subjects

Koller, F.

Publications and source records attributed to Koller, F..

3 recordsLinked to original sources

bioRxiv2022

Anatomical drivers of stomatal conductance in sorghum lines with different leaf widths grown under different temperatures

O_LIImprovements in leaf water use efficiency (iWUE) can maintain crop productivity in water limited environments under rising temperatures. We investigated the leaf anatomical traits which underpin our recently identified link between leaf width (LW) and iWUE. C_LIO_LITen sorghum lines with varying LW were grown under three temperatures to expand the range of variation of both LW and gas exchange rates. Leaf gas exchange, surface morphology and cross-sectional anatomy were measured and analysed using structural equations modelling. C_LIO_LINarrower leaves had lower stomatal conductance (gs) and higher iWUE across growth temperatures. They also had smaller intercellular airspaces, stomatal size, percentage of open stomatal aperture relative to maximum, hydraulic pathway, mesophyll thickness, and leaf mass per area. Structural modelling revealed a developmental association among leaf anatomical traits that underpinned gs variation in sorghum. C_LIO_LIGrowing temperature and LW both impacted leaf gas exchange rates, but only LW directly impacted leaf anatomy. Wider leaves may be more productive under well-watered conditions, but consume more water for growth and development, which is detrimental under water stress. C_LI HighlightCoordination between leaf width and leaf anatomy underpins stomatal conductance variation in sorghum grown under different temperatures.

plant biology↗

bioRxiv2022

HSV-1 infection induces a downstream shift of promoter-proximal pausing linked to H2A.Z-containing +1 nucleosomes

Herpes simplex virus 1 (HSV-1) infection exerts a profound shut-off of host gene expression at multiple levels. Recently, HSV-1 infection was reported to also impact promoter-proximal RNA Polymerase II (Pol II) pausing, a key step in the eukaryotic transcription cycle, with decreased and increased Pol II pausing observed for activated and repressed genes, respectively. Here, we demonstrate that HSV-1 infection induces more complex alterations in promoter-proximal pausing than previously suspected for the vast majority of cellular genes. While pausing is generally retained, it is shifted to more downstream and less well-positioned sites for most host genes. We exclude that this is an artefact of alternative de novo transcription initiation at downstream sites or read-in transcription originating from disruption of transcription termination for upstream genes. Use of downstream 2nd pause sites associated with +1 nucleosomes was previously observed upon NELF depletion. However, downstream shifts of Pol II pausing upon HSV-1 infection are much more pronounced than observed upon NELF depletion. Thus, our study reveals a novel aspect in which HSV-1 infection fundamentally reshapes host transcriptional processes with implications for our understanding of maintenance of promoter-proximal Pol II pausing in eukaryotic cells.

molecular biology↗

bioRxiv2020

Transcriptional regulation of the Nε-fructoselysine metabolism in Escherichia coli by global and substrate-specific cues

Thermally processed food is an important part of the human diet. Heat-treatment, however, promotes the formation of so-called Amadori rearrangement products (ARPs), such as fructoselysine. The gut microbiota including Escherichia coli can utilize these compounds as a nutrient source. While the degradation route for fructoselysine is well described, regulation of the corresponding pathway genes frlABCD remained poorly understood. Here we use bioinformatics combined with molecular and biochemical analyses and show that in E. coli, fructoselysine metabolism is tightly controlled at the transcriptional level. The global regulator Crp (CAP), as well as the alternative sigma factor {sigma}32 (RpoH) contribute to promoter activation at high cAMP-levels and heat stress, respectively. In addition, we identified and characterized a transcriptional regulator FrlR, encoded adjacent to frlABCD, as fructoselysine-6-phosphate specific roadblock repressor. Our study provides profound evidence that the interplay of global and substrate-specific regulation is a perfect adaptation strategy to efficiently utilize unusual substrates within the human gut environment. Abbreviated SummaryThermal food processing promotes the formation of Amadori rearrangement products (ARPs), such as fructoselysine. The gut microbiota including Escherichia coli can utilize these compounds as a nutrient source. We show that in E. coli, fructoselysine metabolism is tightly controlled at the transcriptional level by global and substrate-specific regulators. Their interplay is a perfect adaptation strategy to efficiently utilize fructoselysine within the human gut environment. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=119 SRC="FIGDIR/small/904318v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@15bbc3borg.highwire.dtl.DTLVardef@1a2e3eforg.highwire.dtl.DTLVardef@12261c6org.highwire.dtl.DTLVardef@412c7e_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗