scholarly journals DNA-binding activity of simian virus 40 large T antigen correlates with a distinct phosphorylation state.

1984 ◽  
Vol 50 (1) ◽  
pp. 1-12 ◽  
Author(s):  
K H Scheidtmann ◽  
M Hardung ◽  
B Echle ◽  
G Walter
Keyword(s):  
Dna Binding ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Binding Activity ◽  
T Antigen ◽  
Large T Antigen ◽  
Phosphorylation State ◽  
Dna Binding Activity

scholarly journals Role of Single-Stranded DNA Binding Activity of T Antigen in Simian Virus 40 DNA Replication

2001 ◽  
Vol 75 (6) ◽  
pp. 2839-2847 ◽  
Author(s):  
Chunxiao Wu ◽  
Rupa Roy ◽  
Daniel T. Simmons
Keyword(s):  
Dna Replication ◽  
Dna Binding ◽  
Single Point ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Binding Activity ◽  
T Antigen ◽  
Amino Acid Residues ◽  
Single Stranded Dna ◽  
Dna Binding Activity

ABSTRACT We have previously mapped the single-stranded DNA binding domain of large T antigen to amino acid residues 259 to 627. By using internal deletion mutants, we show that this domain most likely begins after residue 301 and that the region between residues 501 and 550 is not required. To study the function of this binding activity, a series of single-point substitutions were introduced in this domain, and the mutants were tested for their ability to support simian virus 40 (SV40) replication and to bind to single-stranded DNA. Two replication-defective mutants (429DA and 460EA) were grossly impaired in single-stranded DNA binding. These two mutants were further tested for other biochemical activities needed for viral DNA replication. They bound to origin DNA and formed double hexamers in the presence of ATP. Their ability to unwind origin DNA and a helicase substrate was severely reduced, although they still had ATPase activity. These results suggest that the single-stranded DNA binding activity is involved in DNA unwinding. The two mutants were also very defective in structural distortion of origin DNA, making it likely that single-stranded DNA binding is also required for this process. These data show that single-stranded DNA binding is needed for at least two steps during SV40 DNA replication.

scholarly journals Studies on the origin-specific DNA-binding domain of simian virus 40 large T antigen.

1987 ◽  
Vol 61 (10) ◽  
pp. 3326-3330 ◽  
Author(s):  
M Strauss ◽  
P Argani ◽  
I J Mohr ◽  
Y Gluzman
Keyword(s):  
Dna Binding ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Large T Antigen

scholarly journals A Highly Organized Structure Mediating Nuclear Localization of a Myb2 Transcription Factor in the Protozoan Parasite Trichomonas vaginalis

2011 ◽  
Vol 10 (12) ◽  
pp. 1607-1617 ◽  
Author(s):  
Chien-Hsin Chu ◽  
Lung-Chun Chang ◽  
Hong-Ming Hsu ◽  
Shu-Yi Wei ◽  
Hsing-Wei Liu ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Trichomonas Vaginalis ◽  
Simian Virus 40 ◽  
Binding Activity ◽  
T Antigen ◽  
Structural Domain ◽  
Dna Binding Activity

ABSTRACT Nuclear proteins usually contain specific peptide sequences, referred to as nuclear localization signals (NLSs), for nuclear import. These signals remain unexplored in the protozoan pathogen, Trichomonas vaginalis . The nuclear import of a Myb2 transcription factor was studied here using immunodetection of a hemagglutinin-tagged Myb2 overexpressed in the parasite. The tagged Myb2 was localized to the nucleus as punctate signals. With mutations of its polybasic sequences, 48KKQK51 and 61KR62, Myb2 was localized to the nucleus, but the signal was diffusive. When fused to a C-terminal non-nuclear protein, the Myb2 sequence spanning amino acid (aa) residues 48 to 143, which is embedded within the R2R3 DNA-binding domain (aa 40 to 156), was essential and sufficient for efficient nuclear import of a bacterial tetracycline repressor (TetR), and yet the transport efficiency was reduced with an additional fusion of a firefly luciferase to TetR, while classical NLSs from the simian virus 40 T-antigen had no function in this assay system. Myb2 nuclear import and DNA-binding activity were substantially perturbed with mutation of a conserved isoleucine (I74) in helix 2 to proline that altered secondary structure and ternary folding of the R2R3 domain. Disruption of DNA-binding activity alone by point mutation of a lysine residue, K51, preceding the structural domain had little effect on Myb2 nuclear localization, suggesting that nuclear translocation of Myb2, which requires an ordered structural domain, is independent of its DNA binding activity. These findings provide useful information for testing whether myriad Mybs in the parasite use a common module to regulate nuclear import.

One exon of the human LSF gene includes conserved regions involved in novel DNA-binding and dimerization motifs

1994 ◽  
Vol 14 (8) ◽  
pp. 5076-5087
Author(s):  
M K Shirra ◽  
Q Zhu ◽  
H C Huang ◽  
D Pallas ◽  
U Hansen
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Binding Activity ◽  
Protein Protein Interaction ◽  
Dna Binding Activity ◽  
Dna Binding Sites ◽  
Alternative Mrna Splicing ◽  
Alternatively Spliced

The transcription factor LSF, identified as a HeLa protein that binds the simian virus 40 late promoter, recognizes direct repeats with a center-to-center spacing of 10 bp. The characterization of two human cDNAs, representing alternatively spliced mRNAs, provides insight into the unusual DNA-binding and oligomerization properties of LSF. The sequence of the full-length LSF is identical to that of the transcription factors alpha CP2 and LBP-1c and has similarity to the Drosophila transcription factor Elf-1/NTF-1. Using an epitope-counting method, we show that LSF binds DNA as a homodimer. LSF-ID, which is identical to LBP-1d, contains an in-frame internal deletion of 51 amino acids resulting from alternative mRNA splicing. Unlike LSF, LSF-ID did not bind LSF DNA-binding sites. Furthermore, LSF-ID did not affect the binding of LSF to DNA, suggesting that the two proteins do not interact. Of three short regions with a high degree of homology between LSF and Elf-1/NTF-1, LSF-ID lacks two, which are predicted to form beta-strands. Double amino acid substitutions in each of these regions eliminated specific DNA-binding activity, similarly to the LSF-ID deletion. The dimerization potential of these mutants was measured both by the ability to inhibit the binding of LSF to DNA and by direct protein-protein interaction studies. Mutations in one homology region, but not the other, functionally eliminated dimerization.

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