Biology subjects

Gross, H.

Publications and source records attributed to Gross, H..

4 recordsLinked to original sources

bioRxiv2024

A new class of receptors: Lipids regulate mammalian Gsalpha-stimulated adenylyl cyclase activities via their membrane anchors

The biosynthesis of cAMP by mammalian membrane-bound adenylyl cyclases (mACs) is predominantly regulated by G-protein-coupled-receptors (GPCRs). Up to now the two hexahelical transmembrane domains of mACs were considered to fix the enzyme to membranes. Here we show that the transmembrane domains serve in addition as signal receptors and transmitters of lipid signals that control Gs-stimulated mAC activities. We identify aliphatic fatty acids and anandamide as receptor ligands of mAC isoforms 1 to 7 and 9. The ligands enhance (mAC isoforms 2, 3, 7, and 9) or attenuate (isoforms 1, 4, 5, and 6) Gs-stimulated mAC activities in vitro and in vivo. Substitution of the stimulatory membrane receptor of mAC3 by the inhibitory receptor of mAC5 results in a ligand inhibited mAC5-mAC3 chimera. Thus, we discovered a new class of membrane receptors in which two signaling modalities are at a crossing, direct tonic lipid and indirect phasic GPCR-Gs signaling regulating the biosynthesis of cAMP.

biochemistry↗

bioRxiv2024

Multiple regulators control the biosynthesis of brasilicardin in Nocardia terpenica

Brasilicardin A, BraA, is a secondary metabolite produced by the bacterium Nocardia terpenica, and a promising drug due to its potent immunosuppressive activity and low cytotoxicity. Currently, a semisynthetic approach confers production of a complete compound but suffers from insufficient heterologous biosynthesis of BraA intermediates used in the chemical semi-synthesis steps leading to only lab scale quantities of the compound. A better understanding of the involved gene expression regulatory pathways within the brasilicardin biosynthetic gene cluster, Bra-BGC, is a prerequisite to further improve production titers. However, the transcriptional regulation of the Bra-BGC has only been superficially analyzed, till now. In this study, we comprehensively analyze the functions of several unstudied transcriptional regulators, KstR, SdpR and OmpR, encoded within the close vicinity of the Bra-BGC, and delve into the role of the previously described cluster-situated activator Bra12. We present, that Bra12 and the novel regulator SdpR, bind several DNA sequences located in the promoter regions of the genes essential for BraA biosynthesis. Subsequently, we demonstrate the complex regulatory network through which both regulators are capable of controlling activity of those gene promoters and thus gene expression in Bra-BGC. Furthermore, using the heterologous producer strain Amycolatopsis japonicum, we present, that Bra12 and SdpR regulators play opposite roles in brasilicardin congener biosynthesis. Finally, we propose a comprehensive model of multilevel gene expression regulation in Bra-BGC and propose the roles of locally encoded transcriptional regulators.

molecular biology↗

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↗

bioRxiv2022

Convergent evolution of plant pattern recognition receptors sensing cysteine-rich patterns from three microbial kingdoms

The Arabidopsis thaliana receptor-like protein RLP30 contributes to immunity against the fungal pathogen Sclerotinia sclerotiorum. Here we identified the RLP30-ligand as a small cysteine-rich protein (SCP) that occurs in many fungi and oomycetes and is also recognized by the Nicotiana benthamiana RLP RE02. However, RLP30 and RE02 share little sequence similarity and respond to different parts of the native/folded protein. Interestingly, some Brassicaceae other than Arabidopsis also respond to a linear SCP peptide, suggesting that SCP is an eminent immune target that led to the convergent evolution of distinct immune receptors in plants. Surprisingly, RLP30 shows a second ligand specificity for a SCP-nonhomologous protein secreted by bacterial Pseudomonads. RLP30 expression in N. tabacum resulted in lower susceptibility to bacterial, fungal and oomycete pathogens, thus demonstrating that detection of immunogenic patterns by Arabidopsis RLP30 is involved in defense against pathogens from three microbial kingdoms.

plant biology↗