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Molecular cloning of Drosophila HCF reveals proteolytic processing and self‐association of the encoded protein
Author(s) -
Mahajan Shahana S.,
Johnson Kristina M.,
Wilson Angus C.
Publication year - 2003
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.10193
Subject(s) - drosophila (subgenus) , cloning (programming) , biology , genetics , molecular cloning , microbiology and biotechnology , gene , peptide sequence , computer science , programming language
HCF‐1 functions as a coactivator for herpes simplex virus VP16 and a number of mammalian transcription factors. Mature HCF‐1 is composed of two subunits generated by proteolytic cleavage of a larger precursor at six centrally‐located HCF PRO repeats. The resulting N‐ and C‐terminal subunits remain tightly associated via two complementary pairs of self‐association domains: termed SAS1N‐SAS1C and SAS2N‐SAS2C. Additional HCF proteins have been identified in mammals (HCF‐2) and Caenorhabditis elegans (CeHCF). Both contain well‐conserved SAS1 domains but do not undergo proteolytic processing. Thus, the significance of the cleavage and self‐association of HCF‐1 remains enigmatic. Here, we describe the isolation of the Drosophila HCF homologue (dHCF) using a genetic screen based on conservation of the SAS1 interaction. The N‐terminal β‐propeller domain of dHCF supports VP16‐induced complex formation and is more similar to mammalian HCF‐1 than other homologues. We show that full‐length dHCF expressed in Drosophila cells undergoes proteolytic cleavage giving rise to tightly associated N‐ and C‐terminal subunits. As with HCF‐1, the SAS1N and SAS1C elements of dHCF are separated by a large central region, however, this sequence lacks obvious homology to the HCF PRO repeats required for HCF‐1 cleavage. The conservation of HCF processing in insect cells argues that formation of separate N‐ and C‐terminal subunits is important for HCF function. © 2002 Wiley‐Liss, Inc.