Comprehensive Analysis of the Gut Microbiome and Post-Translational Modifications Elucidates the Route Involved in Microbiota-host Interactions

The gut microbiome interacts with the host to maintain body homeostasisits and dysbiosis features in many diseases. The underlying mechanisms of gut microbe regulation of host behavior and brain functions remain unclear. This study aimed to elucidate the influence of gut microbiota on brain functions via post-translational modifications mechanisms under the presence of bacteria and sterile state without any stimulation. We performed a succinylome analysis of hippocampal proteins in GF and SPF mice and metagenomics of feces from SPF mice. And integrated these results with previously reported hippocampal acetylome and phosphorylome data from the same batch. Then followed by bioinformatics analyses. 584 succinylation sites on 455 proteins were identified, including up-regulation of 54 succinylation sites on 91 proteins and down-regulation of 99 sites on 51 proteins in GF compared to SPF. We constructed a panoramic map of gut microbiota-regulated succinylation, acetylation, and phosphorylation, and identified the “cross-talk” and relative independence between different types of post-translational modifications in modulating complicated intracellular pathways. A Pearson correlation analysis indicated that 13 taxa, mainly belonging to Bacteroidetes, correlated with the biological functions of post-translational modifications. Positive correlations between these taxa and succinylation and negative correlations with acetylation were identified in modulating the intracellular pathways. This is the first report of hippocampal physiological changes induced by the absence of gut microbiota and proteomic quantification of succinylation, phosphorylation and acetylation, which contributes to understanding the involvement of the gut microbiome in brain function and behavioral phenotypes.