Biology subjects

LI, G.-W.

Publications and source records attributed to LI, G.-W..

4 recordsLinked to original sources

bioRxiv2026

EF-P-resolved ribosome stalling and collision trigger Rae1-mediated mRNA decay

Ribosome stalling compromises proteome integrity and cellular fitness, and requires efficient mechanisms to eliminate problematic mRNAs and rescue blocked ribosomes. We previously identified Rae1 as an endoribonuclease that cleaves mRNAs at the tail end of stalled ribosomes to promote mRNA degradation in Bacillus subtilis. Here, we show that Rae1 has a broader role in the quality control of mRNAs that encounter translation problems. Global 5-end sequencing identified 31 previously unknown Rae1 cleavage sites, many of them associated with ribosome pausing at polyproline motifs in the absence of elongation factor P (EF-P). We also demonstrate that Rae1 cleaves mRNAs with ribosomes stalled on truncated transcripts lacking a stop-codon (non-stop mRNAs), provided that the transcript is sufficiently long to accommodate multiple collided ribosomes. Rae1 cleavage depends on a cytosine-poor context at the cut site, showing that both ribosome collisions and RNA sequence at the cleavage site govern the ability of Rae1 to promote the removal of stalled ribosomes from mRNA.

microbiology↗

bioRxiv2026

The defining features of intrinsic transcription terminators

Transcription terminators are universal landmarks that delimit RNAs and tune downstream gene expression, yet the sequence rules that define them remain elusive. The classical model of bacterial intrinsic termination--an RNA hairpin followed by a uracil-rich tract--is incomplete, as stem-preserving mutations can abolish termination. By precisely mapping termination sites across 104 sequences, we uncovered a previously unresolved feature required for intrinsic termination: dinucleotides positioned at both edges of the transcription bubble, resembling the elemental RNA polymerase pause signal. Together, hairpin, U-tract and bubble-edge sequences (HUB) account for most variation in termination efficiency and pinpoint bona fide terminators across diverse bacterial phyla. These findings establish HUB as the defining element of intrinsic terminators and provide a framework for decoding and engineering gene expression across genomes.

molecular biology↗

bioRxiv2026

RNase J2 is a specificity factor that governs global mRNA stability in Bacillus subtilis

Ribonucleases (RNases) play a key role in modulating gene expression at the post-transcriptional level, enabling bacteria to rapidly adapt to their environment. The B. subtilis genome encodes more than 20 RNases and understanding the role of each of these enzymes is crucial for a comprehensive knowledge of bacterial post-transcriptional adaptation mechanisms. Among these, RNase J1 and J2, belonging to the {beta}-lactamase enzyme family, form a heterodimer. While the primary function of RNase J1 as a 5'-exoribonuclease in B. subtilis has been known for some time, the role of RNase J2, encoded by the rnjB gene, has remained unclear. Indeed, it has been considered a minor degradation factor due its very weak 5'-exoribonuclease in vitro, the lack of a growth phenotype and the limited number of mRNAs with altered equilibrium levels in rnjB mutants. In this study, we demonstrate that the absence of RNase J2 influences pellicle and macro-colony biofilm formation, as well as swarming in B. subtilis. We show that RNase J2 plays a far more global role in governing mRNA half-lives than originally thought, by stimulating RNase J1-mediated degradation of a subset of RNase J1's mRNA substrates. An inter-subunit contact between RNase J1 and J2 is crucial for RNase J2 action. Altogether, our results suggest that RNase J2 acts primarily as a specificity co-factor for RNase J1 rather than as a ribonuclease per se.

microbiology↗

bioRxiv2021

Ubiquitous mRNA decay fragments in E. coli redefine the functional transcriptome

Bacterial mRNAs have short life cycles, in which transcription is rapidly followed by translation and degradation within seconds to minutes. The resulting diversity of mRNA molecules across different life-cycle stages impacts their functionality but has remained unresolved. Here we quantitatively map the 3' status of cellular RNAs in Escherichia coli during steady-state growth and report a large fraction of molecules (median>60%) that are fragments of canonical full-length mRNAs. The majority of RNA fragments are decay intermediates, whereas nascent RNAs contribute to a smaller fraction. Despite the prevalence of decay intermediates in total cellular RNA, these intermediates are underrepresented in the pool of ribosome-associated transcripts and can thus distort quantifications for the abundance of full-length, functional mRNAs. The large heterogeneity within mRNA molecules in vivo highlights the importance in discerning functional transcripts and provides a lens for studying the dynamic life cycle of mRNAs.

molecular biology↗