Hemeproteins are essential for life and heme insertion is an essential step in their maturation. Maturation of hemeprotein requires that they incorporate heme and become active, but knowledge of this essential cellular process remains incomplete. However recent studies on chaperon Hsp90 has revealed that it drives functional heme insertion in vital hemeproteins like inducible nitric oxide synthase (iNOS), soluble guanylate cyclase (sGC) and hemoglobin (Hb). In all three cases Hsp90 interacts with the heme-free or apo-protein and then drives the heme insertion by an ATP dependent process before dissociating from the heme-replete proteins. Given the diverse role of chaperon Hsp90, and in particular to it being a major therapeutic target in drug discovery programs these findings add up to Hsp90’s repertoire of being a druggable target and opens up more avenues in regulating growth of diseased cells in those pathologic conditions where these hemeproteins are dysfunctional.
