Details

Autor(en) / Beteiligte

• Garcia, Cecelia A
• Narrett, Jackson A
• Gardner, Jeffrey G
• Master, Emma R.

Titel

Trehalose Degradation by Cellvibrio japonicus Exhibits No Functional Redundancy and Is Solely Dependent on the Tre37A Enzyme

Ist Teil von

• Applied and environmental microbiology, 2020-10, Vol.86 (22)

Ort / Verlag

United States: American Society for Microbiology

Erscheinungsjahr

2020

Quelle

MEDLINE

Beschreibungen/Notizen

• The α-diglucoside trehalose has historically been known as a component of the bacterial stress response, though it more recently has been studied for its relevance in human gut health and biotechnology development. The utilization of trehalose as a nutrient source by bacteria relies on carbohydrate-active enzymes, specifically those of the glycoside hydrolase family 37 (GH37), to degrade the disaccharide into substituent glucose moieties for entry into metabolism. Environmental bacteria using oligosaccharides for nutrients often possess multiple carbohydrate-active enzymes predicted to have the same biochemical activity and therefore are thought to be functionally redundant. In this study, we characterized trehalose degradation by the biotechnologically important saprophytic bacterium This bacterium possesses two predicted α-α-trehalase genes, and , and our investigation using mutational analysis found that only the former is essential for trehalose utilization by Heterologous expression experiments found that only the expression of the gene in an mutant strain allowed for full utilization of trehalose. Biochemical characterization of GH37 activity determined that the gene product is solely responsible for cleaving trehalose and is an acidic α-α-trehalase. Bioinformatic and mutational analyses indicate that Tre37A directly cleaves trehalose to glucose in the periplasm, as does not possess a phosphotransferase system. This study facilitates the development of a comprehensive metabolic model for α-linked disaccharides in and more broadly expands our understanding of the strategies that saprophytic bacteria employ to capture diverse carbohydrates from the environment. The metabolism of trehalose is becoming increasingly important due to the inclusion of this α-diglucoside in a number of foods and its prevalence in the environment. Bacteria able to utilize trehalose in the human gut possess a competitive advantage, as do saprophytic microbes in terrestrial environments. While the biochemical mechanism of trehalose degradation is well understood, what is less clear is how bacteria acquire this metabolite from the environment. The significance of this report is that by using the model saprophyte , we were able to functionally characterize the two predicted trehalase enzymes that the bacterium possesses and determined that the two enzymes are not equivalent and are not functionally redundant. The results and approaches used to understand the complex physiology of α-diglucoside metabolism from this study can be applied broadly to other polysaccharide-degrading bacteria.