scholarly journals Mutations in the N-Terminus of VP5 Alter Its Interaction with the Scaffold Proteins of Herpes Simplex Virus Type 1

Virology ◽  
2001 ◽  
Vol 284 (2) ◽  
pp. 308-316 ◽  
Author(s):  
Susan C. Warner ◽  
Gabriela Chytrova ◽  
Prashant Desai ◽  
Stanley Person
2000 ◽  
Vol 74 (15) ◽  
pp. 6838-6848 ◽  
Author(s):  
Amy K. Sheaffer ◽  
William W. Newcomb ◽  
Jay C. Brown ◽  
Min Gao ◽  
Sandra K. Weller ◽  
...  

ABSTRACT Herpes simplex virus type 1 (HSV-1) capsids are initially assembled with an internal protein scaffold. The scaffold proteins, encoded by overlapping in-frame UL26 and UL26.5 transcripts, are essential for formation and efficient maturation of capsids. UL26 encodes an N-terminal protease domain, and its C-terminal oligomerization and capsid protein-binding domains are identical to those of UL26.5. The UL26 protease cleaves itself, releasing minor scaffold proteins VP24 and VP21, and the more abundant UL26.5 protein, releasing the major scaffold protein VP22a. Unlike VP21 and VP22a, which are removed from capsids upon DNA packaging, we demonstrate that VP24 (containing the protease domain) is quantitatively retained. To investigate factors controlling UL26 capsid incorporation and retention, we used a mutant virus that fails to express UL26.5 (ΔICP35 virus). Purified ΔICP35 B capsids showed altered sucrose gradient sedimentation and lacked the dense scaffold core seen in micrographs of wild-type B capsids but contained capsid shell proteins in wild-type amounts. Despite C-terminal sequence identity between UL26 and UL26.5, ΔICP35 capsids lacking UL26.5 products did not contain compensatory high levels of UL26 proteins. Therefore, HSV capsids can be maintained and/or assembled on a minimal scaffold containing only wild-type levels of UL26 proteins. In contrast to UL26.5, increased expression of UL26 did not compensate for the ΔICP35growth defect. While indirect, these findings are consistent with the view that UL26 products are restricted from occupying abundant UL26.5 binding sites within the capsid and that this restriction is not controlled by the level of UL26 protein expression. Additionally, ΔICP35 capsids contained an altered complement of DNA cleavage and packaging proteins, suggesting a previously unrecognized role for the scaffold in this process.


2007 ◽  
Vol 81 (24) ◽  
pp. 13659-13667 ◽  
Author(s):  
Soma Chattopadhyay ◽  
Sandra K. Weller

ABSTRACT UL9, a superfamily II helicase, is a multifunctional protein required for herpes simplex virus type 1 replication in vivo. Although the C-terminal 317-amino-acid DNA binding domain of UL9 exists as a monomer, the full-length protein behaves as a dimer in solution. Thus, it has been assumed that the N-terminal 534 residues contain a region necessary for efficient dimerization and that UL9 dimers are in a head-to-head configuration. We recently showed, however, that residues in the N terminus could modulate the inhibitory properties of UL9 by decreasing the DNA binding ability of the C terminus (S. Chattopadhyay and S. K. Weller, J. Virol. 80:4491-4500, 2006). We suggested that a direct interaction between the N- and C-terminal portions of UL9 might exist and serve to modulate the DNA binding activities of the C terminus. In this study, we used a coimmunoprecipitation assay to show that the N-terminal portion of UL9 can indeed directly interact with the C terminus. A series of truncation mutant proteins were used to show that a region in the N terminus between residues 293 and 321 is necessary for efficient interaction. Similarly, a region in the C terminus between residues 600 and 800 is required for this interaction. The simplest model to explain these data is that UL9 dimers are oriented in a head-to-tail arrangement in which the N terminus is in contact with the C terminus.


2001 ◽  
Vol 120 (5) ◽  
pp. A136-A137
Author(s):  
K TSAMAKIDES ◽  
E PANOTOPOULOU ◽  
D DIMITROULOPOULOS ◽  
M CHRISTOPOULO ◽  
D XINOPOULOS ◽  
...  

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