Trehalose-6-phosphate-mediated phenotypic change in Acinetobacter baumannii

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Trehalose, a stress protectant in Acinetobacter baumannii, is synthesized via the OtsA/OtsB pathway.
• Previous research linked trehalose to virulence and growth phenotypes, but this was based solely on otsB deletion mutants.

Purpose of the Study:

• To investigate the specific roles of trehalose and trehalose-6-phosphate in Acinetobacter baumannii physiology.
• To re-evaluate the contribution of the OtsA/OtsB pathway to bacterial stress tolerance and growth.

Main Methods:

• Construction and phenotypic analysis of Acinetobacter baumannii ∆otsA and ∆otsBA mutants.
• Measurement of intracellular trehalose and trehalose-6-phosphate concentrations using NMR and enzymatic assays.
• Assessment of growth under high salt and high temperature conditions.
• Analysis of trehalose-6-phosphate accumulation upon expression of otsA in a ∆otsB background.

Main Results:

• Only deletion of otsB, not otsA or otsBA, resulted in impaired growth at high temperatures and salinities.
• Mutants did not accumulate trehalose; however, the ∆otsB mutant accumulated trehalose-6-phosphate due to impaired phosphatase activity.
• Expression of otsA in a ∆otsB mutant led to growth inhibition and trehalose-6-phosphate accumulation, even without trehalose synthesis induction.

Conclusions:

• Trehalose-6-phosphate, rather than trehalose, is responsible for the observed growth impairments in Acinetobacter baumannii.
• Trehalose-6-phosphate negatively affects multiple physiological processes in A. baumannii ATCC 19606.
• The OtsA/OtsB pathway's role in stress tolerance is mediated by the accumulation of trehalose-6-phosphate.