Biology subjects

Schrader, J. M.

Publications and source records attributed to Schrader, J. M..

21 records · Page 2Linked to original sources

bioRxiv2019

Global transcriptome analysis of the Myxococcus xanthus multicellular developmental program

The bacteria Myxococcus xanthus exhibit a complex multicellular life cycle. In the presence of nutrients, cells prey cooperatively. Upon starvation, they enter a developmental cycle wherein cells aggregate to produce macroscopic fruiting bodies filled with resistant myxospores. We used RNA-Seq technology to examine the global transcriptome of the 96 h developmental program. This data revealed that many genes were sequentially expressed in discrete modules, with expression peaking during aggregation, in the transition from aggregation to sporulation, or during sporulation. Analysis of genes expressed at each specific time point provided a global framework integrating regulatory factors coordinating motility and differentiation in the developmental program. These data provided insights as to how starving cells obtain energy and precursors necessary for assembly of fruiting bodies and into developmental production of secondary metabolites. This study offers the first global view of developmental transcriptional profiles and provides an important scaffold for future studies. IMPACT STATEMENTInvestigation of global gene expression profiles during formation of the Myxococcus xanthus specialized biofilm reveals a genetic regulatory network that coordinates cell motility, differentiation, and secondary metabolite production.

microbiology↗

bioRxiv2019

Absolute measurements of mRNA translation in C. crescentus reveal important fitness costs of vitamin B12 scavenging

Caulobacter crescentus is a model for the bacterial cell cycle which culminates in asymmetric cell division, yet little is known about the absolute levels of protein synthesis of the cellular parts needed to complete the cell cycle. Here we utilize ribosome profiling to provide absolute measurements of mRNA translation of the C. crescentus genome, providing an important resource for the complete elucidation of the cell cycle gene-regulatory program. Analysis of protein synthesis rates revealed [~]4.5% of cellular protein synthesis are for genes related to vitamin B12 import (btuB) and B12 independent methionine biosynthesis (metE) when grown in common growth media lacking B12. While its facultative B12 lifestyle provides a fitness advantage in the absence of B12, we find that it provides lower fitness of the cells in the presence of B12, potentially explaining why many Caulobacter species have lost the metE gene and become obligates for B12.

microbiology↗

bioRxiv2017

Spatial organization and dynamics of RNase E and ribosomes in Caulobacter crescentus

We report the dynamic spatial organization of Caulobacter crescentus RNase E (RNA degradosome) and ribosomal protein L1 (ribosome) using 3D single particle tracking and super-resolution microscopy. RNase E formed clusters along the central axis of the cell, while weak clusters of ribosomal protein L1 were deployed throughout the cytoplasm. These results contrast with RNase E and ribosome distribution in E. coli, where RNase E co-localizes with the cytoplasmic membrane and ribosomes accumulate in polar nucleoid-free zones. For both RNase E and ribosomes in Caulobacter, we observed a decrease in confinement and clustering upon transcription inhibition and subsequent depletion of nascent RNA, suggesting that RNA substrate availability for processing, degradation, and translation facilitates confinement and clustering. Moreover, RNase E cluster positions correlate with the subcellular location of chromosomal loci of two highly transcribed ribosomal RNA genes, suggesting that RNase Es function in ribosomal RNA processing occurs at the site of rRNA synthesis. Thus, components of the RNA degradosome and ribosome assembly are spatiotemporally organized in Caulobacter, with chromosomal readout serving as the template for this organization.

biophysics↗