pSW2, a Novel Low-Temperature-Inducible Gene Expression Vector Based on a Filamentous Phage of the Deep-Sea Bacterium Shewanella piezotolerans WP3
ABSTRACTA low-temperature-inducible protein expression vector (pSW2) based on a filamentous phage (SW1) of the deep-sea bacteriumShewanella piezotoleransWP3 was constructed. This vector replicated stably inEscherichia coliandShewanellaspecies, and its copy number increased at low temperatures. The pSW2 vector can be utilized as a complementation plasmid in WP3, and it can also be used for the production of complex cytochromes with multiple heme groups, which has the potential for application for metal ion recovery or bioremediation. Promoters of low-temperature-inducible genes in WP3 were fused into the vector to construct a series of vectors for enhancing protein expression at low temperature. The maximum green fluorescent protein intensity was obtained when the promoter for thehfqgene was used. The WP3/pSW2 system can efficiently produce a patatin-like protein (PLP) from a metagenomic library that tends to form inclusion bodies inE. coli. The yields of PLP in the soluble fraction were 8.3 mg/liter and 4.7 mg/liter of culture at 4°C and 20°C, respectively. Moreover, the pSW2 vector can be broadly utilized in otherShewanellaspecies, such asS. oneidensisandS. psychrophila.