title: ATPase activity of a yeast secretory glycoprotein allows ER exit during inactivation of COPII components Sec24p and Sec13p.
abstract: Proteins exit the endoplasmic reticulum (ER) in vesicles pinching off from the membrane at sites covered by the COPII coat, which consists of Sec23/24p and Sec13/31p. We have shown that the glycoprotein Hsp150 exits the ER in the absence of Sec13p or any member of the Sec24p family. The determinant responsible for this resides in the C-terminal domain of Hsp150 (CTD). Here, A- and B-type Walker motifs were identified in the CTD. Authentic Hsp150 from the yeast culture medium, as well as Hsp150 and the CTD fragment produced in Escherichia coli, exhibited ATPase activity nearly three times higher than the published activity of the ER chaperone Kar2p/BiP. Deletion of the Walker motif, and a K335A mutation in it, abolished the ATPase activity. Hsp150 homologues Pir3p and Pir4p, differing in critical amino acids of the Walker motif, also lacked ATPase activity. Unexpectedly, inactivation of the ATPase activity blocked ER exit of Hsp150 in the absence of Sec24p or Sec13p function, whereas secretion in normal cells was not compromised. To our knowledge this is the first documentation of the ATPase activity of a protein serving an intracellular transport function.
authors: Programme in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Finland. taina.suntio@helsinki.fi
authors: Taina
authors: T
authors: Suntio
authors: Sergey A
authors: SA
authors: Shiryaev
authors: Marja
authors: M
authors: Makarow
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D006023:Glycoproteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008565:Membrane Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D028861:Nuclear Pore Complex Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017384:Sequence Deletion
chemical_list: D006023:Glycoproteins; C074229:HSP150 protein, S cerevisiae; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D028861:Nuclear Pore Complex Proteins; D011994:Recombinant Proteins; C079620:SEC13 protein, S cerevisiae; C118289:SEC24 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases