Biology subjects

Schwank, K.

Publications and source records attributed to Schwank, K..

3 recordsLinked to original sources

bioRxiv2023

Ribosomal RNA synthesis by RNA polymerase I is regulated by premature termination of transcription.

The RNA polymerase I (Pol I) enzyme that synthesizes large rRNA precursors, exhibits high rate of pauses during elongation, indicative of a discontinuous process. We show here that Premature Termination of Transcription (PTT) by Pol I is a critical regulatory step limiting rRNA production in vivo. The Pol I mutant, SuperPol (RPA135-F301S), produces 1.5-fold more rRNA than the wild type (WT). Combined CRAC and rRNA analysis link increased rRNA production in SuperPol to reduced PTT, resulting in shifting polymerase distribution toward the 3 end of rDNA genes. In vitro, SuperPol shows reduced nascent transcript cleavage, associated with more efficient transcript elongation after pauses, to the detriment of transcriptional fidelity. Notably, SuperPol is resistant to BMH-21, a drug impairing Pol I elongation and inducing proteasome-mediated degradation of Pol I subunits. Compared to WT, SuperPol maintains subunit stability and sustains high transcription levels upon BMH-21 treatment. These comparative results show that PTT is alleviated in SuperPol while it is stimulated by BMH-21 in WT Pol I.

molecular biology↗

bioRxiv2019

RNA polymerase I passage through nucleosomes depends on its lobe binding subunits

RNA polymerase I (Pol I) is a highly efficient enzyme specialized to synthesize most of the ribosomal RNA. After nucleosome deposition at each round of replication the Pol I transcription machinery has to deal with nucleosomal barriers. It was suggested that Pol I-associated factors facilitate chromatin transcription, but it is not known whether Pol I has an intrinsic capacity to transcribe through nucleosomes. Here we used in vitro transcription assays to study purified Pol I of the yeast S. cerevisiae and Pol I mutants in comparison to Pol II and Pol III to pass a nucleosome. Under identical conditions, purified Pol I and Pol III, but not Pol II, were able to transcribe nucleosomal templates. Pol I mutants lacking either the heterodimeric subunit Rpa34.5/Rpa49 or the C-terminal part of the specific subunit Rpa12.2 showed a lower processivity on naked DNA templates, which was even more reduced in the presence of a nucleosome. The contribution of Pol I specific subunit domains to efficient passage through nucleosomes in context with transcription rate and processivity is discussed.

biochemistry↗

bioRxiv2018

An archaeal symbiont-host association from the deep terrestrial subsurface

DPANN archaea have reduced metabolic capacities and are diverse and abundant in deep aquifer ecosystems, yet little is known about their interactions with other microorganisms that reside there. Here, we provide evidence for an archaeal host-symbiont association from a deep aquifer system at the Colorado Plateau (Utah, USA). The symbiont, Candidatus Huberiarchaeum crystalense, and its host, Ca. Altiarchaeum hamiconexum, show a highly significant co-occurrence pattern over 65 metagenome samples collected over six years. The physical association of the two organisms was confirmed with genome-informed fluorescence in situ hybridization depicting small cocci of Ca. H. crystalense attached to Ca. A. hamiconexum cells. Based on genomic information, Ca. H. crystalense has a similar metabolism as Nanoarchaeum equitans and potentially scavenges vitamins, sugars, nucleotides, and reduced redox-equivalents from its host. These results provide insight into host-symbiont interactions among members of two uncultivated archaeal phyla that thrive in a deep subsurface aquifer.

microbiology↗