pKillerRed-mem is a mammalian expression vector encoding membrane-targeted KillerRed (see reporter description). KillerRed localized on cellular membrane can be used for effective light-induced cell killing.

Note: Comparing to the mitochondrially targeted KillerRed, irradiation of membrane-localized KillerRed leads to even more effective and fast cell death (within 10-30 min). Moreover, membrane-targeted KillerRed was shown to be suitable for the light induced cell killing within a developing zebrafish.

KillerRed codon usage is optimized for high expression in mammalian cells (humanized) [Haas et al., 1996]. Membrane localization signal (MLS) of neuromodulin is linked to the KillerRed N-terminus. The MLS (N-terminal 20 amino acid residues of neuromodulin) contains a signal for posttranslational palmitoylation of cysteines 3 and 4 that targets KillerRed to cellular membranes [Skene and Virag, 1989].

pKillerRed-mem vector can be used as a source of MLS-KillerRed hybrid sequence. The vector backbone contains unique restriction sites that permit its excision and further insertion into expression vector of choice.

Note: The plasmid DNA was isolated from dam⁺-methylated E. coli. Therefore some restriction sites are blocked by methylation. If you wish to digest the vector using such sites you will need to transform the vector into a dam^- host and make fresh DNA.

The vector backbone contains immediate early promoter of cytomegalovirus (P_{CMV IE}) for protein expression, SV40 origin for replication in mammalian cells expressing SV40 T-antigen, pUC origin of replication for propagation in E. coli, and f1 origin for single-stranded DNA production. SV40 polyadenylation signals (SV40 poly A) direct proper processing of the 3'-end of the reporter mRNA.

SV40 early promoter (P_SV40) provides neomycin resistance gene (Neo^r) expression to select stably transfected eukaryotic cells using G418. Bacterial promoter (P) provides kanamycin resistance gene expression (Kan^r) in E. coli. Kan^r/Neo^r gene is linked with herpes simplex virus (HSV) thymidine kinase (TK) polyadenylation signals.

pKillerRed-mem vector can be transfected into mammalian cells by any known transfection method. CMV promoter provides strong, constitutive expression of memrane-targeted KillerRed in eukaryotic cells. If required, stable transformants can be selected using G418 [Gorman, 1985].

Note: KillerRed shows no cell toxic effects before light activation. Upon green light irradiation KillerRed generates reactive oxygen species (ROS) that damage the neighboring molecules.

Suitable host strains for propagation in E. coli include DH5alpha, HB101, XL1-Blue, and other general purpose strains. Plasmid incompatibility group is pMB1/ColE1. The vector confers resistance to kanamycin (30 μg/ml) to E. coli hosts. Copy number in E. coli is about 500.