YadQ of Escherichia coli is a homolog of the mammalian chloride channels of
the ClC family, The yadQ gene was cloned as a fusion protein with a hexahi
stidine tag and tobacco etch virus protease site for the removal of the tag
, The protein was expressed in the membrane of E, coli and extracted with d
ecylmaltoside, Purification was achieved by metal affinity chromatography f
ollowed by cation exchange, Circular dichroism revealed a high alpha-helica
l content. Size exclusion chromatography suggests that YadQ forms dimers, T
he similarity in primary, secondary, and quaternary structure and the abili
ty to recombinantly express YadQ in the cell membrane make the protein a go
od candidate for the structural study of CIC chloride channels. (C) 2000 Fe
deration of European Biochemical Societies.