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Kleemann, L.

Publications and source records attributed to Kleemann, L..

2 recordsLinked to original sources

A rapid protocol for ribosome profiling of low input samples

Ribosome profiling provides quantitative, comprehensive, and high-resolution snapshots of cellular translation by the high-throughput sequencing of short mRNA fragments that are protected from nucleolytic digestion by ribosomes. While the overall principle is simple, the workflow of ribosome profiling experiments is complex and challenging, and typically requires large amounts of sample, limiting its broad applicability. Here, we present a new protocol for ultra-rapid ribosome profiling from low-input samples. It features a robust strategy for sequencing library preparation within one day that employs solid phase purification of reaction intermediates, allowing to reduce the input to as little as 0.1 pmol of RNA. Hence, it is particularly suited for the analyses of small samples or targeted ribosome profiling. Its high sensitivity and its ease of implementation will foster the generation of higher quality data from small samples, which opens new opportunities in applying ribosome profiling.

systems biology↗

DAP5 enables translation re-initiation on structured messenger RNAs

Half of mammalian transcripts contain short upstream open reading frames (uORFs) that potentially regulate translation of the downstream coding sequence (CDS). The molecular mechanisms governing these events remain poorly understood. Here we find that the non-canonical initiation factor Death-associated protein 5 (DAP5 or eIF4G2) is selectively required for re-initiation at the main CDS following uORF translation. Using ribosome profiling and luciferase-based reporters coupled with mutational analysis we show that DAP5-mediated re-initiation occurs on messenger RNAs (mRNAs) with long, structure-prone 5' leader sequences and persistent uORF translation. These mRNAs preferentially code for signalling factors such as kinases and phosphatases. We also report that cap/eIF4F- and eIF4A-dependent recruitment of DAP5 to the mRNA facilitates re-initiation by unrecycled post-termination 40S subunits. Our study reveals important mechanistic insights into how a non-canonical translation initiation factor involved in stem cell fate shapes the synthesis of specific signalling factors.

molecular biology↗