Identification and characterization of a moonlighting protein-enolase for surface display in Streptococcus thermophilus.
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ABSTRACT: BACKGROUND:Streptococcus thermophilus is an important food starter and receiving more attention to serve as cell factories for production of high-valued metabolites. However, the low yields of intracellular or extracellular expression of biotechnological and biomedical proteins limit its practical applications. RESULTS:Here, an enolase EnoM was identified from S. thermophilus CGMCC7.179 with about 94% identities to the surface-located enolases from other Streptococcus spp. strains. The EnoM was used as an anchor to achieve surface display in S. thermophilus using GFP as a reporter. After respectively mixing the GFP-EnoM fusion protein or GFP with S. thermophilus cells in vitro, the relative fluorescence units (RFU) of the S. thermophilus cells with GFP-EnoM was 80-folds higher than that with purified GFP. The sharp decrease in the RFU of sodium dodecyl sulfate (SDS) pretreated cells compared to those of non-pretreated cells demonstrated that the membrane proteins were the binding ligand of EnoM. Furthermore, an engineered ?-galactosidase (?-Gal) was also successfully displayed on the cell surface of S. thermophilus CGMCC7.179 and the relative activity of the immobilized ?-Gal remained up to 64% after reused 8 times. Finally, we also demonstrated that EnoM could be used as an anchor for surface display in L. casei, L. bulgaricus, L. lactis and Leuconostoc lactis. CONCLUSION:To our knowledge, EnoM from S. thermophilus was firstly identified as an anchor and successfully achieved surface display in LAB. The EnoM-based surface display system provided a novel strategy for the enzyme immobilization.
SUBMITTER: Mu Y
PROVIDER: S-EPMC7301973 | biostudies-literature | 2020 Jun
REPOSITORIES: biostudies-literature
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