STRESS-DEPENDENT AND SEQUENCE-DEPENDENT RELEASE INTO THE CULTURE-MEDIUM OF HIV-1 NEF PRODUCED IN SACCHAROMYCES-CEREVISIAE

We have produced human immunodeficiency virus type 1 (HIV-1) Nef (a my ristylated 206-amino-acid protein) in Saccharomyces cerevisiae and sho wn that, while Nef is normally found as a predominantly intracellular protein, amounts up to 40 mu g/ml of Nef are also released into the ex tracellular medium during stress. By electrophoretic (SDS-PAGE) analys is the extracellular Nef is indistinguishable from intracellular Nef. Conditions of stress that lead to the release of Nef include elevated levels of copper or magnesium ions or growth at elevated temperatures. This release appears to be dependent upon the N-terminal sequences of Nef, including the presence of a myristylation site. Our observations concerning Nef release in yeast suggest new ways in which the behavio ur of Nef should be examined in order to gain further insights into th e development of AIDS. If the release of Nef is important in the devel opment of AIDS, our work reveals that Nef-associated symptoms may be r educed or delayed by reducing stresses, such as fevers.