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FEBS J. 2017 Dec;284(24):4298-4313. doi: 10.1111/febs.14309. Epub 2017 Nov 17.

Trehalose acts as a uridine 5'-diphosphoglucose-competitive inhibitor of trehalose 6-phosphate synthase in Corynebacterium glutamicum.

Author information

1
Research Institute of Innovative Technology for the Earth, Kizugawa, Japan.
2
Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Japan.

Abstract

Trehalose is a compatible solute widely distributed in nature. The most prevalent pathway for its synthesis starts from condensation of glucose 6-phosphate (Glc6P) and uridine 5'-diphosphoglucose (UDP-Glc) catalyzed by trehalose 6-phosphate synthase (TPS). A previous laboratory evolution experiment with the bacterium Corynebacterium glutamicum generated strains adapted to supraoptimal temperatures, and the R328H substitution of the TPS encoded by otsA was shown to be associated with thermotolerance acquired by the evolved strains. In this study, we found that the OtsA:R328H substitution promotes both intra- and extracellular trehalose accumulation and demonstrated that build-up of intracellular trehalose accounts for the OtsAR328H -dependent thermotolerance, using the mycobacterial trehalose-specific transporter. Counterintuitively, characterization of the recombinant OtsA proteins revealed that the mutation downshifts the temperature optimum of OtsA. A search for the molecular basis of OtsAR328H -dependent enhancement of trehalose synthesis led to the unexpected findings that trehalose is an effective inhibitor of OtsA and that OtsAR328H is highly tolerant to the trehalose-mediated inhibition. The only available report on such feedback regulation of TPS is for the silk moth from over 50 years ago [Murphy TA and Wyatt GR (1965) J Biol Chem 240, 1500-1508]. While trehalose acts as a Glc6P-competitive inhibitor in the silk moth, the disaccharide was found to inhibit OtsA in a UDP-Glc-competitive manner in C. glutamicum, suggesting independent origins of the negative feedback regulations found for the two species. We showed that overexpression of the wild-type OtsA counteracts the trehalose-dependent regulation and restores the evolved strain-like phenotype to the isogenic wild-type otsA revertant, demonstrating that thermotolerance conferred by OtsAR328H is attributable to its feedback-resistant property.

KEYWORDS:

Corynebacterium glutamicum ; OtsA; negative feedback; trehalose; trehalose 6-phosphate synthase

PMID:
29076621
DOI:
10.1111/febs.14309
[Indexed for MEDLINE]
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