Biology subjects

Lampe, S.

Publications and source records attributed to Lampe, S..

3 recordsLinked to original sources

bioRxiv2024

Proteome-wide quantification of inositol pyrophosphate-protein interactions

Inositol polyphosphates (InsPs) and inositol pyrophosphates (PP-InsPs) constitute a group of highly phosphorylated molecules that are involved in many cellular signaling processes. To characterize discrete signaling events of these structurally closely related molecules, a mass spectrometry approach was developed to derive apparent binding constants for these ligands on a proteome-wide scale. The method employed a series of chemically synthesized, biotinylated affinity reagents for inositol hexakisphosphate (InsP6), and the inositol pyrophosphates 1PP-InsP5, 5PP-InsP5 and 1,5(PP)2-InsP4 (also termed InsP8). Application of these affinity reagents at different concentrations, in combination with tandem mass tag (TMT) labeling, provided binding data for thousands of proteins from a mammalian cell lysate. Investigation of different enrichment conditions, where Mg2+ ions were either available or not, showcased a strong influence of Mg2+ on the protein binding capacities of PP-InsPs. Gene ontology analysis closely linked PP-InsP-interacting proteins to RNA processing in the nucleus and nucleolus. Subsequent data analysis enabled a targeted search for protein pyrophosphorylation among PP-InsP interactors, and identified four new pyrophosphorylated proteins. The data presented here constitute a valuable resource for the community, and application of the method reported here to other biological contexts will enable the exploration of PP-InsP dependent signaling pathways across species.

biochemistry↗

bioRxiv2024

Nucleoside diphosphate kinase A (NME1) catalyze its own oligophosphorylation

Protein phosphorylation is a central regulatory mechanism in eukaryotic cell signaling, and was recently expanded to include protein pyrophosphorylation and protein polyphosphorylation. Here, we report the discovery of yet another mode of phosphorylation - protein oligophosphorylation. Using site-specifically phosphorylated and pyrophosphorylated nucleoside diphosphate kinase A (NME1), the effects of these modifications on enzyme activity were investigated. Phosphorylation, and more so pyrophosphorylation, on threonine 94 notably reduced the nucleoside diphosphate kinase activity. Nevertheless, both phosphoprotein and pyrophosphoprotein were able to catalyze their own oligophosphorylation - up to the formation of a hexaphosphate chain - using ATP as a co-factor. This reaction was critically dependent on the catalytic histidine residue H118, and cryo-EM analysis of the differently modified proteins suggests an intramolecular phosphoryl transfer, likely via a phosphohistidine intermediate. Oligophosphorylation of NME1 in biochemical samples, as well as cell lysates, was further confirmed using mass spectrometry, and oligophophorylation promoted a new set of protein interactions. Our results highlight the complex nature of phosphoregulation, and the methods described here provide the opportunity to investigate the impact of this novel modification in the future.

biochemistry↗

bioRxiv2023

Bioinformatics-Guided Discovery of Biaryl-Tailored Lasso Peptides

Lasso peptides are a class of ribosomally synthesized and post-translationally modified peptides (RiPPs) that feature an isopeptide bond and a distinct lariat fold. A growing number of secondary modifications have been described that further decorate lasso peptide scaffolds. Using genome mining, we have discovered a pair of lasso peptide biosynthetic gene clusters (BGCs) that include cytochrome P450 genes. Here, we report the structural characterization of two unique examples of (C-N) biaryl-containing lasso peptides. Nocapeptin A, from Nocardia terpenica, is tailored with Trp-Tyr crosslink while longipepetin A, from Longimycelium tulufanense, features Trp-Trp linkage. Besides the unusual bicyclic frame, longipepetin A receives an S-methylation by a new Met methyltransferase resulting in unprecedented sulfonium-bearing RiPP. Our bioinformatic survey revealed P450(s) and further maturating enzyme(s)-containing lasso BGCs awaiting future characterization.

biochemistry↗