Distinct SIV-specific CD8+ T cells in the lymph node exhibit simultaneous effector and stem-like profiles and are associated with limited SIV persistence.

Human immunodeficiency virus (HIV) cure efforts are increasingly focused on harnessing CD8+ T cell functions, which requires a deeper understanding of CD8+ T cells promoting HIV control. Here we identifiy an antigen-responsive TOXhiTCF1+CD39+CD8+ T cell population with high expression of inhibitory receptors and low expression of canonical cytolytic molecules. Transcriptional analysis of simian immunodeficiency virus (SIV)-specific CD8+ T cells and proteomic analysis of purified CD8+ T cell subsets identified TOXhiTCF1+CD39+CD8+ T cells as intermediate effectors that retained stem-like features with a lineage relationship with terminal effector T cells. TOXhiTCF1+CD39+CD8+ T cells were found at higher frequency than TCF1-CD39+CD8+ T cells in follicular microenvironments and were preferentially located in proximity of SIV-RNA+ cells. Their frequency was associated with reduced plasma viremia and lower SIV reservoir size. Highly similar TOXhiTCF1+CD39+CD8+ T cells were detected in lymph nodes from antiretroviral therapy-naive and antiretroviral therapy-suppressed people living with HIV, suggesting this population of CD8+ T cells contributes to limiting SIV and HIV persistence.

Copper(I)-nitrene platform for chemoproteomic profiling of methionine.

Methionine plays a critical role in various biological and cell regulatory processes, making its chemoproteomic profiling indispensable for exploring its functions and potential in protein therapeutics. Building on the principle of rapid oxidation of methionine, we report Copper(I)-Nitrene Platform for robust, and selective labeling of methionine to generate stable sulfonyl sulfimide conjugates under physiological conditions. We demonstrate the versatility of this platform to label methionine in bioactive peptides, intact proteins (6.5-79.5 kDa), and proteins in complex cell lysate mixtures with varying payloads. We discover ligandable proteins and sites harboring hyperreactive methionine within the human proteome. Furthermore, this has been utilized to profile oxidation-sensitive methionine residues, which might increase our understanding of the protective role of methionine in diseases associated with elevated levels of reactive oxygen species. The Copper(I)-Nitrene Platform allows labeling methionine residues in live cancer cells, observing minimal cytotoxic effects and achieving dose-dependent labeling. Confocal imaging further reveals the spatial distribution of modified proteins within the cell membrane, cytoplasm, and nucleus, underscoring the platform's potential in profiling the cellular interactome.