The C-terminal domain of human grp94 protects the catalytic subunit of protein kinase CK2 (CK2alpha) against thermal aggregation. Role of disulfide bonds.
The C-terminal domain (residues 518-803) of the 94 kDa glucose regulated protein (grp94) was expressed in Escherichia coli as a fusion protein with a His6-N-terminal tag (grp94-CT). This truncated form of grp94 formed dimers and oligomers that could be dissociated into monomers by treatment with dithiothreitol. Grp94-CT conferred protection against aggregation on the catalytic subunit of protein kinase CK2 (CK2alpha), although it did not protect against thermal inactivation. This anti-aggregation effect of grp94-CT was concentration dependent, with full protection achieved at grp94-CT/CK2alpha molar ratios of 4 : 1. The presence of dithiothreitol markedly reduced the anti-aggregation effects of grp94-CT on CK2alpha without altering the solubility of the chaperone. It is concluded that the chaperone activity of the C-terminal domain of human grp94 requires the maintenance of its quaternary structure (dimers and oligomers), which seems to be stabilised by disulphide bonds.
Roher
N
N
Departament de Bioquímica i Biologia Molecular. Facultat de Ciències, Universitat Autònoma de Barcelona, Spain.
Miró
F
F
Boldyreff
B
B
Llorens
F
F
Plana
M
M
Issinger
O G
OG
Itarte
E
E
D047390:Casein Kinase II; D020134:Catalytic Domain / Q000187:drug effects; D004220:Disulfides / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000494:pharmacology*; D018832:Molecular Chaperones / Q000235:genetics / Q000494:pharmacology*; D010446:Peptide Fragments / Q000235:genetics / Q000494:pharmacology*; D011489:Protein Denaturation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects*; D020836:Protein Structure, Quaternary / Q000187:drug effects; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000494:pharmacology
D004220:Disulfides; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D010446:Peptide Fragments; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; C018551:glucose-regulated proteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D004229:Dithiothreitol