title: Genetic improvement of butanol tolerance in Escherichia coli by cell surface expression of fish metallothionein.
abstract: Cysteine-rich metallothioneins (MTs) have been reported to possess the capacity to scavenge reactive oxygen species in vitro and in vivo. Recombinant strains of Escherichia coli expressing outer membrane protein C (OmpC) fused with MTs from human, mouse and tilapia displayed the ability for such surface-localized MTs to scavenge extracellular free radicals, but the benefits of the possible applications of this capacity have not yet been demonstrated. Because the intrinsic butanol tolerance of microbes has become an impediment for biological butanol production, we examined whether surface-displayed MTs could contribute to butanol tolerance. The results show that strains expressing OmpC-MT fusion proteins had higher butanol tolerance than strains with cytoplasmically expressed MTs. Furthermore, the OmpC-tilapia MT fusion protein enhanced butanol tolerance more strongly than other recombinant constructs. Although the enhanced level of tolerance was not as high as that provided by OmpC-tilapia MT, over-expression of OmpC was also found to contribute to butanol tolerance. These results suggest that free-radical scavenging by MT and OmpC-related osmoregulation enhance butanol tolerance. Our results shed new light on methods for engineering bacteria with higher butanol tolerance.
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, ROC.
authors.forename: Kuo Hsing
authors.initials: KH
authors.lastname: Lin
authors.forename: Wei Chih
authors.initials: WC
authors.lastname: Chin
authors.forename: Ang Hsuan
authors.initials: AH
authors.lastname: Lee
authors.forename: Chieh Chen
authors.initials: CC
authors.lastname: Huang
mesh_terms: D000818:Animals; D000440:Butanols / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018272:Porins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017210:Tilapia
chemical_list: D000440:Butanols; D029941:Fish Proteins; C113724:OmpC protein; D018272:Porins; D011993:Recombinant Fusion Proteins; D008668:Metallothionein