Gram-negative bacteria cause a variety of infections in plants and animals alike.occurrence of Salmonella and Escherichia coli Infectious diseases often make headlines due to their severity, forcing people to rely on symptomatic as well as natural remedies, increasing the burden on healthcare systems. Antibiotics provide an effective solution to bacterial infections, but the increasing incidence of antibiotic-resistant bacteria is prompting researchers to identify other possible treatments for these infections. I am encouraged. With advances in technology and modern medicine, researchers are investigating the possibility of disrupting bacterial pathogenicity at the molecular level by interfering with molecular processes at the gene and protein level.
Gram-negative bacteria, notorious for their infectious potential, produce osmoregulatory periplasmic glucan (OPG), a long-chain carbohydrate composed of multiple glucose units, in the extracellular and/or periplasmic space. Initially, OPG was thought to be a byproduct produced under low solute concentrations, but recent reports have confirmed that OPG is important for virulence, symbiosis, cell adhesion, and signal transduction. Masu.
However, the enzymes involved in OPG synthesis, regulation, and degradation are not completely understood. Through genetic analysis, OPGH and/or opgG Genes partially involved in OPG synthesis are responsible for the loss of bacterial infectivity, suggesting a strong potential association of these genes with bacterial virulence.
The structure of OpgG is E. coli (EcOpgG) was elucidated, and the mechanism of action of OpgG and OpgD was revealed. Escherichia coli (EcOpgG and EcOpgD, respectively) remain unknown. Understanding the enzymes involved in OPG synthesis and the mechanisms underlying their function provides important insights into the pathogenesis of Gram-negative bacteria and has the potential to develop more effective ways to combat bacterial infections. there is.
To fill this knowledge gap, Sei Honuchi of the Tokyo University of Science, Dr. Kaito Kobayashi of the National Institute of Advanced Industrial Science and Technology (AIST), Associate Professor Hiroyuki Nakai of Niigata University, and Professor Masahiro Nakajima of the same university I cooperated. Tokyo University of Science conducted structural and functional analyzes of EcOpgD and EcOpgG. This research communication biology September 21, 2023.
Professor Nakajima talks about the motivation for this research as follows. “Glycans are important biopolymers that play various roles in living organisms, including pathogenicity and symbiosis. Because their structures are extremely diverse and complex, enzymes that synthesize and degrade sugar chains are There are many types, but we humans know only one.” Just a few of them. ”
Researchers investigated the function of OPG-related genes in model organisms. Escherichia coli. Functional analysis revealed the following: Escherichia coli OpgD (EcOpgD) was an endo-β-1,2-glucanase that specifically degraded β-1,2-glucan. It also had kinetic properties similar to common glycoside hydrolases (GHs), further confirming its identity as a β-1,2-glucanase.
Structural analysis using crystallography revealed a high degree of similarity between the structures of EcOpgG and EcOpgD. However, the activities of the two enzymes were significantly different. Upon further investigation, the researchers discovered that several amino acids that form a reaction pathway called “loop A” are important for enzyme activity and regulate the reaction rate. EcOpgG and EcOpgD had different catalytic functions, probably due to amino acid differences in the loop A region. The LoopA region is diverse among this group of enzymes, which may lead to functional diversity. Nevertheless, the basis of the catalytic center is shared by this group of enzymes. This commonality could help scientists develop treatments that could interfere with OPG synthesis and impede the bacteria’s ability to infect.
Furthermore, although the two enzymes belonged to the same GH family, their structures did not match any of the existing GH enzymes. Therefore, the authors confirmed that they belong to a novel GH family, namely GH186. This information paves the way for research into treatments that can target the GH186 protein and halt the progression of bacterial infections.
Professor Masahiro concluded by explaining the long-term applications of the research. “Although it has been known that some Gram-negative plant pathogens synthesize OPG for pathogenic purposes, most of the enzymes important for its synthesis have not been identified, making it difficult to develop pesticides that target OPG. Development is hampered. We have identified a family of enzymes (GH186) involved in OPG. Direct synthesis of OPG and elucidation of its detailed function presents a new target (GH186) for inhibiting pathogens. and provided a solid foundation for “structure-based pesticide discovery.” ”
The results of this study may lay a strong foundation for further research on OPG and related genes, ushering in a new era of disease management.
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Tokyo University of Science
Reference magazines:
Susumu Honnai other. (2023). Identification of the enzymatic function of an osmoregulated periplasmic glucan biosynthesis protein from Escherichia coli reveals a novel family of glycoside hydrolases. communication biology. doi.org/10.1038/s42003-023-05336-6.