scholarly journals NMR Structure of the N-terminal J Domain of Murine Polyomavirus T Antigens

2000 ◽  
Vol 275 (46) ◽  
pp. 36094-36103 ◽  
Author(s):  
Mark V. Berjanskii ◽  
Michael I. Riley ◽  
Anyong Xie ◽  
Valentyna Semenchenko ◽  
William R. Folk ◽  
...  
Keyword(s):  
Nmr Structure ◽  
T Antigens ◽  
Murine Polyomavirus ◽  
J Domain

Hsc70 Contacts Helix III of the J Domain from Polyomavirus T Antigens:  Addressing a Dilemma in the Chaperone Hypothesis of How They Release E2F from pRb†

Biochemistry ◽  
2006 ◽  
Vol 45 (22) ◽  
pp. 6917-6929 ◽  
Author(s):  
Ravindranath Garimella ◽  
Xin Liu ◽  
Wei Qiao ◽  
Xiangyang Liang ◽  
Erik R. P. Zuiderweg ◽  
...  
Keyword(s):  
T Antigens ◽  
J Domain

Hsc70-interacting HPD Loop of the J Domain of Polyomavirus T Antigens Fluctuates in ps to ns and μs to ms

2002 ◽  
Vol 321 (3) ◽  
pp. 503-516 ◽  
Author(s):  
Mark V Berjanskii ◽  
Michael I Riley ◽  
Steven R Van Doren
Keyword(s):  
T Antigens ◽  
J Domain

scholarly journals Transactivation of Murine Cyclin A by Polyomavirus Large and Small T Antigens

2001 ◽  
Vol 75 (14) ◽  
pp. 6498-6507 ◽  
Author(s):  
Stefan Schüchner ◽  
Maria Nemethova ◽  
Aurelia Belisova ◽  
Britta Klucky ◽  
Wolfgang Holnthoner ◽  
...  
Keyword(s):  
Cyclin A ◽  
T Antigen ◽  
S Phase ◽  
Luciferase Reporter ◽  
Large T Antigen ◽  
3T3 Cells ◽  
T Antigens ◽  
J Domain ◽  
Swiss 3T3 ◽  
Small T Antigen

ABSTRACT Polyomavirus large and small T antigens cooperate in the induction of S phase in serum-deprived Swiss 3T3 cells. While the large T antigen is able to induce S phase-specific enzymes, we have recently shown that both T antigens contribute to the production of the cyclins E and A and that the small T antigen is essential for the induction of cyclin A-dependent cdk2 activity (S. Schüchner and E. Wintersberger, J. Virol. 73:9266–9273, 1999). Here we present our attempts to elucidate the mechanisms by which the large and the small T antigens transactivate the murine cyclin A gene. Using Swiss 3T3 cells carrying the T antigens and various mutants thereof under the hormone-inducible mouse mammary tumor virus promoter, as well as transient-cotransfection experiments with the T antigens and cyclin A promoter-luciferase reporter constructs, we found the following. The large T antigen activates the cyclin A promoter via two transcription factor binding sites, a cyclic AMP responsive element (CRE), and the major negative regulatory site called CDE-CHR. While an intact binding site for pocket proteins is required for the function of this T antigen at the CDE-CHR, its activity at the CRE is largely independent thereof. In contrast, an intact J domain and an intact zinc finger are required at both sites. The small T antigen also appears to have an influence on the cyclin A promoter through the CRE as well as the CDE-CHR. For this an interaction with protein phosphatase 2A is essential; mutation of the J domain does not totally eliminate but greatly reduces the transactivating ability.

NMR Structure of the J-domain and the Gly/Phe-rich Region of theEscherichia coliDnaJ Chaperone

1996 ◽  
Vol 260 (2) ◽  
pp. 236-250 ◽  
Author(s):  
Maurizio Pellecchia ◽  
Thomas Szyperski ◽  
Daniel Wall ◽  
Costa Georgopoulos ◽  
Kurt Wüthrich
Keyword(s):  
Nmr Structure ◽  
Rich Region ◽  
J Domain

scholarly journals Genetic Analysis of the Polyomavirus DnaJ Domain

2005 ◽  
Vol 79 (15) ◽  
pp. 9982-9990 ◽  
Author(s):  
Kerry A. Whalen ◽  
Rowena de Jesus ◽  
Jennifer A. Kean ◽  
Brian S. Schaffhausen
Keyword(s):  
Genetic Analysis ◽  
Molecular Chaperones ◽  
Protein Phosphatase ◽  
Single Point ◽  
Point Mutations ◽  
Terminal Sequence ◽  
T Antigens ◽  
Phosphatase 2A ◽  
J Domain ◽  
Single Point Mutations

ABSTRACT Polyomavirus T antigens share a common N-terminal sequence that comprises a DnaJ domain. DnaJ domains activate DnaK molecular chaperones. The functions of J domains have primarily been tested by mutation of their conserved HPD residues. Here, we report detailed mutagenesis of the polyomavirus J domain in both large T (63 mutants) and middle T (51 mutants) backgrounds. As expected, some J mutants were defective in binding DnaK (Hsc70); other mutants retained the ability to bind Hsc70 but were defective in stimulating its ATPase activity. Moreover, the J domain behaves differently in large T and middle T. A given mutation was twice as likely to render large T unstable as it was to affect middle T stability. This apparently arose from middle T's ability to bind stabilizing proteins such as protein phosphatase 2A (PP2A), since introduction of a second mutation preventing PP2A binding rendered some middle T J-domain mutants unstable. In large T, the HPD residues are critical for Rb-dependent effects on the host cell. Residues Q32, A33, Y34, H49, M52, and N56 within helix 2 and helix 3 of the large T J domain were also found to be required for Rb-dependent transactivation. Cyclin A promoter assays showed that J domain function also contributes to large T transactivation that is independent of Rb. Single point mutations in middle T were generally without effect. However, residue Q37 is critical for middle T's ability to form active signaling complexes. The Q37A middle T mutant was defective in association with pp60c-src and in transformation.

scholarly journals The J Domain of Papovaviral Large Tumor Antigen Is Required for Synergistic Interaction with the POU-Domain Protein Tst-1/Oct6/SCIP

1999 ◽  
Vol 19 (4) ◽  
pp. 2455-2464 ◽  
Author(s):  
Elisabeth Sock ◽  
Janna Enderich ◽  
Michael Wegner
Keyword(s):  
T Antigen ◽  
Terminal Region ◽  
Amino Terminus ◽  
Physical Interaction ◽  
Large T Antigen ◽  
T Antigens ◽  
Direct Physical Interaction ◽  
Amino Terminal ◽  
Pou Domain ◽  
J Domain

ABSTRACT Large T antigens from polyomaviruses are multifunctional proteins with roles in transcriptional regulation, viral DNA replication, and cellular transformation. They have been shown to enhance the activity of various cellular transcription factors. In the case of the POU protein Tst-1/Oct6/SCIP, this enhancement involves a direct physical interaction between the POU domain of the transcription factor and the amino-terminal region of large T antigen. Here we have analyzed the structural requirements for synergistic interaction between the two proteins in greater detail. Tst-1/Oct6/SCIP and the related POU protein Brn-1 were both capable of direct physical interaction with large T antigen. Nevertheless, only Tst-1/Oct6/SCIP functioned synergistically with large T antigen. This differential behavior was due to differences in the amino-terminal regions of the proteins, as evident from chimeras between Tst-1/Oct6/SCIP and Brn-1. Synergy was specifically observed for constructs containing the amino-terminal region of Tst-1/Oct6/SCIP. Large T antigen, on the other hand, functioned synergistically with Tst-1/Oct6/SCIP only when the integrity of its J-domain-containing amino terminus was maintained. Mutations that disrupted the J domain concomitantly abolished the ability to enhance the function of Tst-1/Oct6/SCIP. The J domain of T antigen was also responsible for the physical interaction with Tst-1/Oct6/SCIP and could be replaced in this property by other J domains. Intriguingly, a heterologous J domain from a human DnaJ protein partially substituted for the amino terminus of T antigen even with regard to the synergistic enhancement of Tst-1/Oct6/SCIP function. Given the general role of J domains, we propose chaperone activity as the underlying mechanism for synergy between Tst-1/Oct6/SCIP and large T antigens.

scholarly journals Simian Virus 40 T Antigens and J Domains: Analysis of Hsp40 Cochaperone Functions in Escherichia coli

2003 ◽  
Vol 77 (19) ◽  
pp. 10706-10713 ◽  
Author(s):  
Pierre Genevaux ◽  
Florence Lang ◽  
Françoise Schwager ◽  
Jai V. Vartikar ◽  
Kathleen Rundell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Loss Of Function ◽  
T Antigens ◽  
E Coli ◽  
J Domain ◽  
Small T Antigen

ABSTRACT The N-terminal exon of DNA tumor virus T antigens represents a J domain that can direct interaction with the host-encoded Hsp70 chaperones. We have taken advantage of rapid Hsp40 cochaperone assays with Escherichia coli to assess simian virus 40 (SV40)-encoded J-domain loss of function. We found a strong correlation between loss of cochaperone function in E. coli and defective SV40 growth, suggesting that the major role of the J domain in DNA tumor viruses is to provide cochaperone function. We also report the expression of native SV40 virus T antigens in E. coli. Our results show that small t antigen, but not large T antigen (LT) or LT truncation TN125 or TN136, can functionally replace under limited growth conditions DnaJ (Hsp40) function in vivo. In addition, purified small t antigen can efficiently stimulate E. coli DnaK's (Hsp70) ATPase in vitro, thus behaving like a bona fide cochaperone. Furthermore, small t amino acids 83 to 174, which are adjacent to the viral J domain, can replace the E. coli DnaJ J-domain glycine-phenylalanine-rich domain, immediately adjacent to the J-domain sequences, even in the absence of significant amino acid similarity to their DnaJ counterpart. Taken together, our studies demonstrate that functionally related Hsp40 proteins from mammalian viral systems can be rapidly studied in bacteria and exploited to probe the universally conserved Hsp70 chaperone machine mechanism.

Sign in / Sign up

Export Citation Format

Share Document