Biology subjects

Sheng, j.

Publications and source records attributed to Sheng, j..

3 recordsLinked to original sources

bioRxiv2022

Bioorthogonal in-cell Labeling and Profiling of N6-isopentenyladenosine (i6A) Modified RNA

Chemical modifications in RNAs play critical roles in structural diversification and functional regulation of many vital biochemical processes. Several hydrophobic prenyl-modifications have been discovered in a variety of RNA species since the 1990s. Prenyl groups are the feedstocks of terpene and many other biological molecules and the processes of prenylation in different macromolecules have been widely studied. We present here a new chemical biology technique to identify and label i6A, a prenyl-modified RNA residue, based on the unique reactivity of the prenyl group. We also found that iodine-mediated cycloaddition reactions of the prenyl group occurs in a superfast manner, and converts i6A from a hydrogen-bond acceptor into a donor. Based on this reactivity, we developed an iodine-mediated oxidation and reverse transcription (IMORT) method to profile cellular i6A residues with a single-base resolution, allowing for the transcriptome-wide detection and analysis of various i6A-containing RNA species.

biochemistry↗

bioRxiv2022

Bio-orthogonal chemistry-based conjugation strategy facilitates investigation of impacts of s2U, s4U, m1A and m6A guide RNA modifications on CRISPR activity.

The CRISPR-Cas9 system is an important genome editing tool that holds enormous potential towards treatment of human genetic diseases. Clinical success of CRISPR technology is dependent on incorporation of modifications into the single guide RNA (sgRNA). However, chemical synthesis of modified sgRNAs, which are over 100 nucleotides in length, is difficult and low-yielding. We developed a conjugation strategy that utilized bio-orthogonal chemistry to efficiently assemble functional sgRNAs containing nucleobase modifications. The described approach entails the chemical synthesis of two shorter RNA oligonucleotides: a 31-mer containing tetrazine (Tz) group and a 70-mer modified with a trans-cyclooctene (TCO) moiety. The two oligonucleotides were conjugated to form functional sgRNAs. The two-component conjugation methodology was utilized to synthesize a library of sgRNAs containing nucleobase modifications such as m1A, m6A, s2U and s4U. The impacts of these RNA modifications on overall CRISPR activity was investigated in vitro and in Cas9-expressing HEK293T cells.

biochemistry↗

bioRxiv2022

Nature-Inspired Chemical Probes for in-cell Labeling of Lipidized RNA and Identification of New Regulatory Enzymes

RNA modifications play pivotal roles in numerous cellular processes and human diseases. In addition to well-studied methyl-based modifications, hydrophobic prenyl-modifications have also been found in many RNA species. Here we report two chemical labeling strategies for tagging lipid-modified RNAs by taking advantage of a natural SelU-mediated tRNA geranylation process and the special reactivity of prenyl-groups. We synthesized a series of clickable geranyl-pyrophosphate analogs and identified two candidates for indirect RNA labeling using a two-step process, azidation-and-click-tagging of fluorescent dyes, namely ACT-Flu. We also developed a direct metabolic incorporation and biorthogonal tagging (MIBT-Tag) method based on the Ene-ligation of prenyl-groups. Both methods have been successfully applied to in-cell RNA labeling and the identification of new proteins associated with the geranylation process through proteomic and bioinformatic studies. These biochemical toolsets enable further in vivo applications to study prenylation pathways and monitor their status in both healthy and diseased cells.

biochemistry↗