Crystal structure of an efficacious gonococcal adherence inhibitor: An enolase fromLactobacillus gasseri

Characterization and Structural Analyses of Enolase from Shrimp (Litopenaeus vannamei)

Transcriptome analysis had recognized enolase from shrimp Litopenaeus vannamei (L. vannamei), which is termed LvEnolase, as one of the allergens, but its amino acid sequence and protein structure have been lacking. In this study, natural LvEnolase was isolated from L. vannamei and characterized for the first time. The full-length cDNA sequence of LvEnolase was effectively cloned, which encoded 434 amino acid residues. The crystal structure of LvEnolase was successfully determined at a resolution of 2.5 Å by X-ray crystallography (PDB: 8UEL). Notably, it was observed that near the active center, a loop exists in either an open or closed state, and the open loop was associated with the product release phase. Furthermore, enzyme activity assays were conducted to validate the catalytic capabilities of purified LvEnolase. These findings significantly enhance our comprehension of the enolase family and provide valuable support for delving into the functions and characteristics of LvEnolase.

Molecular Docking of Bacterial Protein Modulators and Pharmacotherapeutics of Carica papaya Leaves as a Promising Therapy for Sepsis: Synchronising In Silico and In Vitro Studies

Sepsis is a serious health concern globally, which necessitates understanding the root cause of infection for the prevention of proliferation inside the host's body. Phytochemicals present in plants exhibit antibacterial and anti-proliferative properties stipulated for sepsis treatment. The aim of the study was to determine the potential role of Carica papaya leaf extract for sepsis treatment in silico and in vitro. We selected two phytochemical compounds, carpaine and quercetin, and docked them with bacterial proteins, heat shock protein (PDB ID: 4PO2), surfactant protein D (PDB ID: 1PW9), and lactobacillus bacterial protein (PDB ID: 4MKS) against imipenem and cyclophosphamide. Quercetin showed the strongest interaction with 1PW9 and 4MKS proteins. The leaves were extracted using ethanol, methanol, and water through Soxhlet extraction. Total flavonoid content, DPPH assay, HPTLC, and FTIR were performed. In vitro cytotoxicity of ethanol extract was screened via MTT assay on the J774 cell line. Ethanol extract (EE) possessed the maximum number of phytocomponents, the highest amount of flavonoid content, and the maximum antioxidant activity compared to other extracts. FTIR analysis confirmed the presence of N-H, O-H, C-H, C=O, C=C, and C-Cl functional groups in ethanol extract. Cell viability was highest (100%) at 25 µg/mL of EE. The present study demonstrated that the papaya leaves possessed antibacterial and cytotoxic activity against sepsis infection.

A Moonlighting Enolase from Lactobacillus gasseri does not Require Enzymatic Activity to Inhibit Neisseria gonorrhoeae Adherence to Epithelial Cells

Enolases are generally thought of as cytoplasmic enzymes involved in glycolysis and gluconeogenesis. However, several bacteria have active forms of enolase associated with the cell surface and these proteins are utilized for functions other than central metabolism. Recently, a surface-associated protein produced by Lactobacillus gasseri ATCC 33323 with homology to enolase was found to inhibit the adherence of the sexually transmitted pathogen, Neisseria gonorrhoeae, to epithelial cells in culture. Here, we show that the protein is an active enolase in vitro. A recombinantly expressed, C-terminal His-tagged version of the protein, His6-Eno3, inhibited gonococcal adherence. Assays utilizing inhibitors of enolase enzymatic activity showed that this inhibitory activity required the substrate-binding site to be in an open conformation; however, the enolase enzymatic activity of the protein was not necessary for inhibition of gonococcal adherence. An L. gasseri strain carrying an insertional mutation in eno3 was viable, indicating that eno3 is not an essential gene in L. gasseri 33323. This observation, along with the results of the enzyme assays, is consistent with reports that this strain encodes more than one enolase. Here we show that the three L. gasseri genes annotated as encoding an enolase are expressed. The L. gasseri eno3 mutant exhibited reduced, but not abolished, inhibition of gonococcal adherence, which supports the hypothesis that L. gasseri inhibition of gonococcal adherence is a multifactorial process.

An integrated metagenome and -proteome analysis of the microbial community residing in a biogas production plant

To study the metaproteome of a biogas-producing microbial community, fermentation samples were taken from an agricultural biogas plant for microbial cell and protein extraction and corresponding metagenome analyses. Based on metagenome sequence data, taxonomic community profiling was performed to elucidate the composition of bacterial and archaeal sub-communities. The community's cytosolic metaproteome was represented in a 2D-PAGE approach. Metaproteome databases for protein identification were compiled based on the assembled metagenome sequence dataset for the biogas plant analyzed and non-corresponding biogas metagenomes. Protein identification results revealed that the corresponding biogas protein database facilitated the highest identification rate followed by other biogas-specific databases, whereas common public databases yielded insufficient identification rates. Proteins of the biogas microbiome identified as highly abundant were assigned to the pathways involved in methanogenesis, transport and carbon metabolism. Moreover, the integrated metagenome/-proteome approach enabled the examination of genetic-context information for genes encoding identified proteins by studying neighboring genes on the corresponding contig. Exemplarily, this approach led to the identification of a Methanoculleus sp. contig encoding 16 methanogenesis-related gene products, three of which were also detected as abundant proteins within the community's metaproteome. Thus, metagenome contigs provide additional information on the genetic environment of identified abundant proteins.

Production of bioactive conjugated linoleic acid by the multifunctional enolase from Lactobacillus plantarum

Lactobacillus plantarum α-enolase, a multifunctional-anchorless-surface protein belonging to the conserved family of enolases with a central role in glycolytic metabolism, was characterized to have a side role in the intricate metabolism of biohydrogenation of linoleic acid, catalyzing the formation of bioactive 9-cis-11-trans-CLA through dehydration and isomerization of 10-hydroxy-12-cis-octadecenoic acid. The identity of the enolase was confirmed through mass spectrometric analysis that showed the characteristic 442 amino acid sequence with a molecular mass of 48.03kDa. The enolase was not capable of using linoleic acid directly as a substrate but instead uses its hydroxyl derivative 10-hydroxi-12-cis-octadecenoic acid to finally form bioactive conjugated linoleic acid. Biochemical optimization studies were carried out to elucidate the conditions for maximum production of 9-cis-11-trans-CLA and maximum stability of α-enolase when catalyzing this reaction. Furthermore, through structural analysis of the protein, we propose the binding sites of substrate and product molecules that were characterized as two hydrophobic superficial pockets located at opposite ends of the enolase connected through a channel where the catalysis of dehydration and isomerization might occur. These results prove that multifunctional α-enolase also plays a role in cell detoxification from polyunsaturated fatty acids such as linoleic acid, along with the linoleate isomerase complex.

Octameric structure of Staphylococcus aureus enolase in complex with phosphoenolpyruvate

Staphylococcus aureus is a Gram-positive bacterium with strong pathogenicity that causes a wide range of infections and diseases. Enolase is an evolutionarily conserved enzyme that plays a key role in energy production through glycolysis. Additionally, enolase is located on the surface of S. aureus and is involved in processes leading to infection. Here, crystal structures of Sa_enolase with and without bound phosphoenolpyruvate (PEP) are presented at 1.6 and 2.45 Å resolution, respectively. The structure reveals an octameric arrangement; however, both dimeric and octameric conformations were observed in solution. Furthermore, enzyme-activity assays show that only the octameric variant is catalytically active. Biochemical and structural studies indicate that the octameric form of Sa_enolase is enzymatically active in vitro and likely also in vivo, while the dimeric form is catalytically inactive and may be involved in other biological processes.