ISOLATION OF THE ATP-BINDING HUMAN HOMOLOG OF THE ARSA COMPONENT OF THE BACTERIAL ARSENITE TRANSPORTER

Arsenite resistance in bacteria is mediated by an efflux pump composed of the arsA and arsB gene products. We have isolated the human homolo g of the bacterial arsA (hARSA-I), a member of the ATPase superfamily with no transmembrane domain. Southern and Northern analyses indicated the presence of two cross-hybridizing genes in the human genome and e xpression of hARSA-I in many tissues. A rabbit antiserum raised agains t a glutathione-S-transferase (GST)/hARSA-I fusion protein identified two cross-reacting proteins of 37 and 42 kDa by Western analysis in tw o different human cell lines. Overexpression of hARSA-I in the embryon al human kidney 293 cell line was accompanied by overproduction of the 37-kDa protein. Biochemical analysis using the GST/hARSA-I fusion pro tein indicated that hARSA-I is an ATPase analogous to the bacterial Ar sA. Thus, hARSA-I is a new eukaryotic member of a highly conserved ATP -binding superfamily of proteins. (C) 1996 Academic Press, Inc.