title: The hemolysin B protein, expressed in Saccharomyces cerevisiae, accumulates in binding-protein (BiP)-containing structures.
abstract: The hemolysin B (Hly B) protein of Escherichia coli, a member of the ABC-transporter family, was expressed in Saccharomyces cerevisiae and tested for its ability to complement a defect in the a-factor transporter Ste6. We found that HlyB was not able to restore mating ability to a STE6 deletion strain. The HlyB protein did not co-fractionate with Ste6 on sucrose gradients, indicating that improper localization of the HlyB protein could contribute to the lack of complementation. Immunofluorescence experiments suggest that HlyB is localized to structures derived from the endoplasmic reticulum (ER). The HlyB-expressing cells revealed a perinuclear staining typical of ER-localized proteins and intensely staining ring-like structures (HlyB-bodies). Double-label immunofluorescence experiments show that the HlyB structures also contain the ER binding protein (BiP), the product of the KAR2 gene. The HlyB protein, however, did not co-fractionate with another ER marker protein, the NADPH cytochrome c reductase. The HlyB bodies could be derivatives of a novel compartment of the early secretory pathway which contains BiP but not other resident ER proteins. In this case, HlyB could serve as a tool for the biochemical characterization of this compartment.
authors.affiliation: Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Kölling
authors.forename: C P
authors.initials: CP
authors.lastname: Hollenberg
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000096:biosynthesis / Q000378:metabolism*; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism*; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006023:Glycoproteins; D006460:Hemolysin Proteins / Q000096:biosynthesis / Q000378:metabolism*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010957:Plasmids; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D005656:Fungal Proteins; D006023:Glycoproteins; D006460:Hemolysin Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; C489277:STE6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; C086257:hemolysin B