Disease relevance of UL26

• Therefore, HSV capsids can be maintained and/or assembled on a minimal scaffold containing only wild-type levels of UL26 proteins [1].
• Characterization of the protease and other products of amino-terminus-proximal cleavage of the herpes simplex virus 1 UL26 protein [2].
• Capsids assembled in the absence of the UL26 gene products had a large-cored phenotype resembling that previously described for the HSV-1 mutant ts1201 which has a lesion in this gene [3].
• The roles of the UL26 and UL26.5 products were investigated using the baculovirus expression system, focusing on the function of the 25 residues cleaved from the UL26.5 protein [4].

High impact information on UL26

• The protease responsible for this process is encoded within the 635-amino acid open reading frame of the UL26 gene of the virus [5].
• In contrast to UL26.5, increased expression of UL26 did not compensate for the DeltaICP35 growth defect [1].
• Evidence for controlled incorporation of herpes simplex virus type 1 UL26 protease into capsids [1].
• This 635-aa protease, encoded by the UL26 gene, is autoproteolytically processed at two sites, the release (R) site between amino acid residues 247 and 248 and the maturation (M) site between residues 610 and 611 [6].
• The mutant virus failed to grow on Vero cells and required a complementing cell line for its propagation, confirming that the UL26 gene product is essential for viral growth [7].

Biological context of UL26

• The UL26 null mutation was constructed by replacement of DNA sequences specifying codons 41 through 593 with a lacZ reporter cassette [8].
• Furthermore, we wished to determine if a virus altered in the UL26 maturation cleavage site at residues 610 and 611 produced a lethal phenotype [9].
• The products of herpes simplex virus type 1 gene UL26 which are involved in DNA packaging are strongly associated with empty but not with full capsids [10].
• Each transcript pair consists of a short species whose 3' end corresponds to a polyadenylation signal located just downstream of the UL24 open reading frame, and a longer species whose 3' end corresponds to a polyadenylation signal located downstream of the UL26 gene [11].
• The level of protease expression was at least 20 times higher with the synthetic gene as compared to the natural UL26 gene [12].

Anatomical context of UL26

• To better understand the functions of the protease in infected cells, we have isolated a complementing cell line (BMS-MG22) and constructed and characterized a null UL26 mutant virus, m100 [7].
• This mutation was lethal and required a transformed cell line expressing wild-type UL26 gene products for growth [13].

Associations of UL26 with chemical compounds

• 5. Subsequent to capsid assembly the scaffold proteins are cleaved at the maturation site by a serine protease also encoded by UL26, thereby enabling the bulk of the scaffold proteins to be released from the capsid [13].

Other interactions of UL26

• Using this cell line we isolated a null mutant virus in the UL38 ORF and a mutant virus that was altered at residues 610 and 611 of the UL26 and UL26.5 gene products [9].
• These results demonstrate the functional equivalency of the cercopithecine monkey virus gB glycoproteins and genes (including transcriptional regulatory elements) in HSV1, the functional nature of HSV1/SA8 chimeric UL28 and UL26 genes/proteins, and that UL28, gB and/or p40 proteins may effect the pathogenicity of HSV1 [14].

Analytical, diagnostic and therapeutic context of UL26

• An attractive target for anti-herpes chemotherapy is the herpes simplex virus 1 (HSV-1) protease encoded by the UL26 gene [12].
• A combination of immunoprecipitation and immunoblotting techniques confirmed that the epitope is located at the carboxy terminus of the UL26 gene product and is downstream of epitopes that are recognized by two monoclonal antibodies [15].

References