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Melo, M. C. R.

Publications and source records attributed to Melo, M. C. R..

2 recordsLinked to original sources

Generalized correlation-based dynamical network analysis: a new high-performance approach for identifying allosteric communications in molecular dynamics trajectories

Molecular interactions are essential for regulation of cellular processes, from the formation of multiprotein complexes, to the allosteric activation of enzymes. Identifying the essential residues and molecular features that regulate such interactions is paramount for understanding the biochemical process in question, allowing for suppression of a reaction through drug interventions, or optimization of a chemical process using bioengineered molecules. In order to identify important residues and information pathways within molecular complexes, the Dynamical Network Analysis method was developed and has since been broadly applied in the literature. However, in the dawn of exascale computing, this method is generally limited to relatively small biomolecular systems. In this work we provide an evolution of the method, application and interface. All data processing and analysis is conducted through Jupyter notebooks, providing automatic detection of important solvent and ion residues, an optimized and parallel generalized correlation implementation that is linear with respect to the number of nodes in the system, and subsequent community clustering, calculation of betweenness of contacts, and determination optimal paths. Using the popular visualization program VMD, high-quality renderings of the networks over the biomolecular structures can be produced. Our new implementation was employed to investigate three different systems, with up to 2.5 M atoms, namely the OMP-decarboxylase, the Leucyl-tRNA synthetase complexed with its cognate tRNA and adenylate, and the respiratory complex I in a membrane environment. Our enhanced and updated protocol provides the community with an intuitive and interactive interface, which can be easily applied to large macromolecular complexes.

biophysics

Bacteria on steroids: the enzymatic mechanism of an NADH-dependent dehydrogenase that regulates the conversion of cortisol to androgen in the gut microbiome

Microorganisms extensively modify host steroids, but whether these reactions merely eliminate hormones or create signals with new biological identities is largely unknown. Gut bacteria have been known for more than four decades to reduce cortisol to 20-dihydrocortisol, yet the physiological consequence of this transformation remained unresolved. Here we show that microbial cortisol reduction creates a distinct host signalling molecule. A 2.0-[A] structure of the bacterial enzyme DesC, together with molecular dynamics, biochemical perturbation and hybrid quantum mechanics/molecular mechanics simulations, defines substrate recognition and an ordered hydride-transfer and proton-relay mechanism. In gnotobiotic mice, isogenic bacteria expressing active DesC--but not a catalytically inactive S47A variant produced 20-dihydrocortisol in the intestine and circulation and reprogrammed colonic transcription. In primary intestinal epithelial cells, 20-dihydrocortisol, but not cortisol, activated ERK-dependent inflammatory and growth-associated programmes. These responses required nuclear receptor subfamily 4 group A member 3 (NR4A3), whose purified ligand-binding domain bound 20-dihydrocortisol but showed no detectable binding to cortisol. A Chicago colonoscopy cohort linked chronic cortisol exposure, faecal desC, the microbial metabolite and colorectal phenotypes. Thus, bacterial metabolism can change receptor selectivity and biological activity rather than simply terminate host hormone action, expanding the endocrine chemistry of the host.

microbiology