However, there is a scarcity of mechanistic data that advances our understanding of taxonomic correlations with pathophysiologic host-microbiome interactions. Notable diseases synonymously associated with dysbiosis include inflammatory bowel diseases, cancers, metabolic disorders, opportunistic and recurrent pathogen infections. Systems biology studies have established that changes in gastrointestinal microbiome composition and function can adversely impact host physiology. Such signaling systems have been therapeutically targeted for the treatment of pain, inflammation, depression, obesity, and diabetes. (E) Endogenous long-chain N-acyl-amides that are structurally related to commendamide are reported to function as agonists for numerous receptors, including many GPCRs. (D) Purified commendamide activates the HEK293:NFκB GFP reporter assay. (C) The structures for three minor clonespecific metabolites related to commendamide (compounds 2-4) were also determined using NMR and MS data. coli transformed with Cbeg12-1, are shown. (B) Key NMR correlations used to define the structure of commendamide (1), the major clone-specific peak found in cultures of E. coli transformed with an empty pJWC1 cosmid vector (i), cosmid Cbeg12-1 (ii), cosmid Cbeg12-2 (iii), cosmid Cbeg12-3 (iv), cosmid Cbeg12-1 with a transposon insertion in the Cbeg12-1 gene (v), Cbeg12-1 subcloned into pJWC1 (vi), and synthetic commendamide (vii). (A) Electrospray ionization (ESI)-mass spectroscopy (MS) traces of culture broth extracts from E. This study shows the utility of functional metagenomics for identifying potential mechanisms used by commensal bacteria for host interactions and outlines a functional metagenomics-based pipeline for the systematic identification of diverse commensal bacteria effectors that impact host cellular functions.Ĭharacterization of commendamide.
G2A has been implicated in disease models of autoimmunity and atherosclerosis. Commendamide resembles long-chain N-acyl-amides that function as mammalian signaling molecules through activation of G-protein-coupled receptors (GPCRs), which led us to the observation that commendamide activates the GPCR G2A/GPR132. This metabolite was also found in culture broth from the commensal bacterium Bacteroides vulgatus, which harbors a gene highly similar to Cbeg12. Detailed analysis of one effector gene family (Cbeg12) recovered from all three patient libraries found that it encodes for the production of N-acyl-3-hydroxypalmitoyl-glycine (commendamide). This screen led to the identification of 26 unique commensal bacteria effector genes (Cbegs) that are predicted to encode proteins with diverse catabolic, anabolic, and ligand-binding functions and most frequently interact with either glycans or lipids. Here, we examine 3,000 Mb of metagenomic DNA cloned from three phenotypically distinct patients for effectors that activate NF-κB, a transcription factor known to play a central role in mediating responses to environmental stimuli. Functional metagenomics provides a systematic means of surveying commensal DNA for genes that encode effector functions. The trillions of bacteria that make up the human microbiome are believed to encode functions that are important to human health however, little is known about the specific effectors that commensal bacteria use to interact with the human host.