Detection of novel enzyme intermediates in PEP-utilizing enzymes

Evaluating cutinase from Fusarium oxysporum as a biocatalyst for the degradation of nine synthetic polymer

Plastic poses a significant environmental impact due to its chemical resilience, leading to prolonged and degradation times and resulting in widespread adverse effects on global flora and fauna. Cutinases are essential enzymes in the biodegradation process of synthetic polymers like polyethylene terephthalate (PET), which recognized organisms can break down. Here, we used molecular dynamics and binding free energy calculations to explore the interaction of nine synthetic polymers, including PET, with Cutinase from Fusarium oxysporum (FoCut). According to our findings, the polymers poly(ethylene terephthalate) (PET), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(butylene succinate) (PBS), poly(butylene adipate-co-terephthalate) (PBAT) and poly(ε-caprolactone) (PCL) can bind to the Cutinase enzyme from F. oxysporum, indicating potential biodegradation activity for these polymers. PET exhibited the highest binding affinity (- 34.26 kcal/mol). Besides PET, the polymers PHBH, PBS, PBAT, and PCL also demonstrated significant affinities for the FoCut enzyme, with binding values of - 18.44, - 29.71, - 22.78, and - 22.26 kcal/mol, respectively. Additionally, analysis of the phylogenetic tree of cutinases produced by different organisms demonstrated that even though the organisms belong to different kingdoms, the cutinase from F. oxysporum (FoCut) showed biological similarity in its activity in degrading polymers with the cutinase enzyme from the bacterium Kineococcus radiotolerans and the fungus Moniliophthora roreri. Furthermore, the phylogenetic analysis demonstrated that the PETase enzyme has a very high similarity with the bacterial cutinase enzyme than with the fungal cutinase, therefore demonstrating that the PETase enzyme from Ideonella sakaiensis can easily be a modified bacterial cutinase enzyme that created a unique feature in biodegrading only the pet polymer through an evolutionary process due to its environment and its biochemical need for carbon. Our data demonstrate that bacterial cutinase enzymes have the same common ancestor as the PETase enzyme. Therefore, cutinases and PETase are interconnected through their biological similarity in biodegrading polymers. We demonstrated that important conserved regions, such as the Ser-Asp-His catalytic triad, exist in the enzyme's catalytic site and that all Cut enzymes from different organisms have the same region to couple with the polymer structures.

Bacterial molecular machinery in the Martian cryosphere conditions

The exploration of Mars is one of the main objectives of space missions since the red planet is considered to be, or was in the past, potentially habitable. Although the surface of Mars is now dry and arid, abundant research suggests that water covered Mars billions of years ago. Recently, the existence of liquid water in subglacial lakes has been postulated below the South pole of Mars. Until now, experiments have been carried out on the survival of microorganisms in Martian surface conditions, but it remains unknown how their adaptation mechanisms would be in the Martian cryosphere. In this work, two bacterial species (Bacillus subtilis and Curtobacterium flacumfaciens) were subjected to a simulated Martian environment during 24 h using a planetary chamber. Afterward, the molecular machinery of both species was studied to investigate how they had been modified. Proteomes, the entire set of proteins expressed by each bacterium under Earth (named standard) conditions and Martian conditions, were compared using proteomic techniques. To establish this evaluation, both the expression levels of each protein, and the variation in their distribution within the different functional categories were considered. The results showed that these bacterial species followed a different strategy. The Bacillus subtilis resistance approach consisted of improving its stress response, membrane bioenergetics, degradation of biomolecules; and to a lesser extent, increasing its mobility and the formation of biofilms or resistance endospores. On the contrary, enduring strategy of Curtobacterium flacumfaciens comprised of strengthening the cell envelope, trying to protect cells from the extracellular environment. These results are especially important due to their implications for planetary protection, missions to Mars and sample return since contamination by microorganisms would invalidate the results of these investigations.

Construction and assessment of reaction models of Class I EPSP synthase. Part II: investigation of the EPSP ketal

Although the proposed mechanisms are reasonable, there are still many questions about the 5-enolpyruvyl shikimate-3-phosphate (EPSP) synthase mechanism that are difficult to answer by experimental means alone. EPSP synthase is a key enzyme in the shikimic acid pathway, which is found only in plants and some micro-organisms and is also molecular target of glyphosate, active component of one of the top-selling herbicides. In the study of reaction mechanism of EPSP synthase, in addition to inorganic phosphate and EPSP products, after long time at equilibrium, it was shown that a side product is formed, the EPSP ketal. In this line, studies using density functional theory (DFT) techniques were performed to investigate the reaction mechanism of formation of EPSP and the corresponding ketal. Our findings indicate some key amino acid residues in the EPSP synthase mechanism and a possible route for the formation of the EPSP ketal.

Cloning, expression, and characterization of sialic acid synthases

The most commonly occurring sialic acid, N-acetylneuraminic acid, is the repeating unit in polysialic acid chain of human neuronal cell adhesion molecule as well as in capsular polysialic acid of neuroinvasive bacteria, Escherichia coli K1 and Neisseria meningitidis. Sialic acid synthesis and polymerization occur in slightly different pathways in animals and bacteria. N-Acetylneuraminic acid (NeuNAc) is synthesized by the condensation of phosphoenolpyruvate and N-acetylmannosamine by NeuNAc synthase in bacteria. The mammalian homologue N-acetylneuraminic acid-9-phosphate (NeuNAc-9-P) synthase uses N-acetylmannosamine-6-phosphate in the condensation reaction to produce NeuNAc-9-P. Both subfamilies of sialic acid synthases possess N-terminal triosephosphate isomerase barrel domain and C-terminal antifreeze protein domain. We report cloning of the genes, expression, purification, and characterization of human NeuNAc-9-P synthase and N. meningitidis NeuNAc synthase. Stability of the purified enzymes and effects of pH and temperature on their activities were evaluated. Enzyme kinetics and preliminary mutagenesis experiments reveal the importance of C-terminal antifreeze protein domain and a conserved cysteine residue for the enzyme activities.

Contemporary mass spectrometry for the direct detection of enzyme intermediates

The field of enzymology has long used small-molecule mass spectrometry. However, the direct interrogation of covalent and non-covalent intermediates by large-molecule mass spectrometry of enzymes or large peptide substrates is illuminating an increasingly diverse array of chemistries used in nature. Recent advances now allow improved detection of several modifications formed at sub-stoichiometric levels on the same polypeptide, and elucidation of intermediate dynamics with low millisecond temporal resolution. Highlighting recent applications in both ribosomal and non-ribosomal biosynthesis of natural products, along with acetyl transferases, sulfonucleotide reducatases, and PEP-utilizing enzymes, the utility of small- and large-molecule mass spectrometry to reveal enzyme intermediates and illuminate mechanism is described briefly. From ever more complex mixtures, mass spectrometry continues to evolve into a key technology for a larger number of today's enzymologists.