Nuclear factor III, a novel sequence-specific DNA-binding protein from HeLa cells stimulating adenovirus DNA replication

Nature ◽  
1986 ◽  
Vol 322 (6080) ◽  
pp. 656-659 ◽  
Author(s):  
Ger J. M. Pruijn ◽  
Wim van Driel ◽  
Peter C. van der Vliet
1979 ◽  
Vol 29 (1) ◽  
pp. 322-327 ◽  
Author(s):  
D J McCorquodale ◽  
J Gossling ◽  
R Benzinger ◽  
R Chesney ◽  
L Lawhorne ◽  
...  

1983 ◽  
Vol 3 (3) ◽  
pp. 315-324 ◽  
Author(s):  
M P Quinlan ◽  
D M Knipe

Two herpes simplex virus proteins, the major capsid protein and the major DNA binding protein, are specifically localized to the nucleus of infected cells. We have found that the major proportion of these proteins is associated with the detergent-insoluble matrix or cytoskeletal framework of the infected cell from the time of their synthesis until they have matured to their final binding site in the cell nucleus. These results suggest that these two proteins may interact with or bind to the cellular cytoskeleton during or soon after their synthesis and throughout transport into the cell nucleus. In addition, the DNA binding protein remains associated with the nuclear skeleton at times when it is bound to viral DNA. Thus, viral DNA may also be attached to the nuclear framework. We have demonstrated that the DNA binding protein and the capsid protein exchange from the cytoplasmic framework to the nuclear framework, suggesting the direct movement of the proteins from one structure to the other. Inhibition of viral DNA replication enhanced the binding of the DNA binding protein to the cytoskeleton and increased the rate of exchange from the cytoplasmic framework to the nuclear framework, suggesting a functional relationship between these events. Inhibition of viral DNA replication resulted in decreased synthesis and transport of the capsid protein. We have been unable to detect any artificial binding of these proteins to the cytoskeleton when solubilized viral proteins were mixed with a cytoskeletal fraction or a cell monolayer. This suggested that the attachment of these proteins to the cytoskeleton represents the actual state of these proteins within the cell.


1983 ◽  
Vol 3 (3) ◽  
pp. 315-324
Author(s):  
M P Quinlan ◽  
D M Knipe

Two herpes simplex virus proteins, the major capsid protein and the major DNA binding protein, are specifically localized to the nucleus of infected cells. We have found that the major proportion of these proteins is associated with the detergent-insoluble matrix or cytoskeletal framework of the infected cell from the time of their synthesis until they have matured to their final binding site in the cell nucleus. These results suggest that these two proteins may interact with or bind to the cellular cytoskeleton during or soon after their synthesis and throughout transport into the cell nucleus. In addition, the DNA binding protein remains associated with the nuclear skeleton at times when it is bound to viral DNA. Thus, viral DNA may also be attached to the nuclear framework. We have demonstrated that the DNA binding protein and the capsid protein exchange from the cytoplasmic framework to the nuclear framework, suggesting the direct movement of the proteins from one structure to the other. Inhibition of viral DNA replication enhanced the binding of the DNA binding protein to the cytoskeleton and increased the rate of exchange from the cytoplasmic framework to the nuclear framework, suggesting a functional relationship between these events. Inhibition of viral DNA replication resulted in decreased synthesis and transport of the capsid protein. We have been unable to detect any artificial binding of these proteins to the cytoskeleton when solubilized viral proteins were mixed with a cytoskeletal fraction or a cell monolayer. This suggested that the attachment of these proteins to the cytoskeleton represents the actual state of these proteins within the cell.


2020 ◽  
Author(s):  
Jemila C. Kester ◽  
Olga Kandror ◽  
Tatos Akopian ◽  
Michael R. Chase ◽  
Junhao Zhu ◽  
...  

The ClpP1P2 proteolytic complex is essential in Mycobacterium tuberculosis (Mtb). Proteolysis by ClpP1P2 requires an associated ATPase, either ClpX or ClpC1. Here, we seek to define the unique contributions of the ClpX ATPase to mycobacterial growth. We formally demonstrate that ClpX is essential for mycobacterial growth and to understand its essential functions, we identify ClpX-His-interacting proteins by pulldown and tandem mass spectrometry. We find an unexpected association between ClpX and proteins involved in DNA replication, and confirm a physical association between ClpX and the essential DNA maintenance protein Single-Stranded DNA Binding protein (SSB). Purified SSB is not degraded by ClpXP1P2; instead SSB enhances ATP hydrolysis by ClpX and degradation of the model substrate GFP-SsrA by ClpXP1P2. This activation of ClpX is mediated by the C-terminal tail of SSB that had been implicated in the activation of other ATPases associated with DNA replication. Consistent with the predicted interactions, depletion of clpX transcript perturbs DNA replication. These data reveal that ClpX participates in DNA replication and identify the first activator of ClpX in mycobacteria. IMPORTANCE Tuberculosis, caused by Mycobacterium tuberculosis, imposes a major global health burden, surpassing HIV and malaria in annual deaths. The ClpP1P2 proteolytic complex and its cofactor ClpX are attractive drug targets, but their precise cellular functions are unclear. This work confirms ClpX’s essentiality and describes a novel interaction between ClpX and SSB, a component of the DNA replication machinery. Further, we demonstrate that a loss of ClpX is sufficient to interrupt DNA replication, suggesting the ClpX-SSB complex may play a role in DNA replication in mycobacteria.


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