Epstein-Barr virus nuclear antigen 5 interacts with HAX-1, a possible component of the B-cell receptor signalling pathway.
Using a yeast two-hybrid screen of a B-cell cDNA library with an Epstein-Barr nuclear antigen 5 (EBNA5) molecule containing seven repeats of the W(1)W(2) domain as bait, we have isolated the EBNA5-interacting protein HAX-1. HAX-1 has previously been shown to associate with HS1, a protein specifically expressed in cells of the haematopoietic lineage, and is thought to be involved in signal transduction in B-cells. Immunofluorescence experiments showed that HAX-1 co-localized with the hsp60 protein that is associated with the mitochondria in the cell cytoplasm. Pull down experiments with a fusion protein between glutathione S-transferase and the seven copy repeat EBNA5 synthesized in bacteria and in yeast cells confirmed that HAX-1 can interact with EBNA5 in vitro. Conventionally, EBNA5 is regarded as a nuclear protein. However, we show here that the smallest EBNA5 species, composed of the unique Y domain and only one copy of the W(1)W(2) repeat domain, like HAX-1, co-localizes with the mitochondrial hsp60 protein in the B-cell cytoplasm. Furthermore, immunoprecipitation experiments demonstrate that the single repeat EBNA5 associates with HAX-1 in transfected B-lymphoblastoid cells.
Dufva
Martin
M
Department of Clinical Chemistry and Transfusion Medicine, Institute of Laboratory Medicine, Göteborg University, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden1.
Olsson
Maria
M
Department of Clinical Chemistry and Transfusion Medicine, Institute of Laboratory Medicine, Göteborg University, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden1.
Rymo
Lars
L
Department of Clinical Chemistry and Transfusion Medicine, Institute of Laboratory Medicine, Göteborg University, Sahlgrenska University Hospital, S-413 45 Gothenburg, Sweden1.
D048868:Adaptor Proteins, Signal Transducing; D001402:B-Lymphocytes / Q000378:metabolism*; D018834:Chaperonin 60 / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D019309:Epstein-Barr Virus Nuclear Antigens / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics; D015151:Immunoblotting; D007150:Immunohistochemistry; D011506:Proteins / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D018834:Chaperonin 60; C421621:EBNA-5 protein, Epstein-Barr virus; D019309:Epstein-Barr Virus Nuclear Antigens; C104759:HAX1 protein, human; D011506:Proteins; D005982:Glutathione Transferase