Table 2.

Expression Vectors Investigated for Vaculor Saporin and Saporin L3 Expression^a

gene	vector	source	promoter	fusion	intended location	result
vacuolar saporin	pET100D	Invitrogen	T7	N-His	cytosol	unstable clone
saporin L3	pET100D	Invitrogen	T7	N-His	cytosol	unstable clone
vacuolar saporin	pBAD-dest49	Invitrogen	araBAD	N-HP-thioredoxin	cytosol	unstable clone
saporin L3	pBAD-dest49	Invitrogen	araBAD	N-HP-thioredoxin	cytosol	unstable clone
saporin L3	pET-39b(+)	Novagen	T7	N-DsbA, N-His	periplasm	unstable clone
saporin L3	pET-31b(+)	Novagen	T7	N-KSI, C-His	inclusion bodies	insoluble
saporin L3	pASK-IBA16	IBA	tetracycline	N-OmpA, N-strep	periplasm	unstable clone
saporin L3	pMAL-p4X	NEB	Ptac	N-secretion signal and MBP	periplasm	unstable clone
saporin L3	pTYB11	NEB	T7	N-CBD	cytosol	unstable clone
saporin L3	pKLAC1	NEB	None	none, yeast expression vector	yeast expression	unstable clone

^aVector sources IBA and NEB are IBA biotagnology and New England Biolabs, respectively. N or C defines the fusion location. His is a purification tag, and HP is a His patch. DsbA is difulfide isomerase I, and KSI is a ketosteroid isomerase gene fragment. OmpA is outer membrane protein A. MBP is maltose binding protein. Strep is a purification tag. CBD is chitin binding domain. Unstable clone describes the failure to select an nonmutated plasmid with the saporin gene inserted into nonexpressing E. coli strains.