BAG-1M, an isoform of Bcl-2-interacting protein BAG-1, enhances gene expression driven by CMV promoter.
BAG-1M, one of the isoforms of BAG-1, was reported to bind to DNA and stimulate general transcription when cells were stressed by heat shock (Zeiner, M., et al., Proc. Natl. Acad. Sci. USA 96, 10194-10199, 1999). Here we show that BAG-1M binds and enhances transcriptional activity of Cytomegalovirus (CMV) early gene promoter under unstressed conditions. This activity is unique to BAG-1M in that other isoforms, BAG-1S and BAG-1L, are much weaker in this activity, although all of the isoforms share common ubiquitin-like domain and BAG domain interacting with Hsp70/Hsc70. Deletion analysis of BAG-1M showed that C-terminal BAG domain is necessary to enhance the CMV promoter activity, suggesting that interaction with Hsp70/Hsc70 proteins may mediate this function. Another mutation in N-terminus, BAG-1M K(2-4)A, lost DNA binding capacity and majority of the promoter-enhancing activity. Our study demonstrates that both N-terminal DNA binding site and C-terminal Hsp70/Hsc70 binding site of BAG-1M play an important role in enhancing the CMV promoter activity.
Takahashi
N
N
Department of Bioengineering, Faculty of Engineering, Soka University, Hachioji, Tokyo 192-8577, Japan.
Sasaki
R
R
Takahashi
J
J
Takayama
S
S
Reed
J C
JC
Andoh
T
T
D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D003587:Cytomegalovirus / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D010957:Plasmids; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000502:physiology; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion; D013312:Stress, Physiological; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
C091732:BCL2-associated athanogene 1 protein; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; D020033:Protein Isoforms; D015534:Trans-Activators; D014157:Transcription Factors