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Identification of the gene coding for the precursor of adenovirus core protein X
1Départment de Microbiologie, Faculté de Médecine Université de Sherbrooke, Québec, Canada.
Abstract:
Nucleoprotein complexes extracted from infected cells (J. Weber and L. Philipson, Virology 136:321-327, 1984) or ts1 virions grown at 39 degrees C (J. M. Weber, G. Khitto, and A. R. Bhatti, Can. J. Microbiol. 29:235-241, 1983) contain, in addition to known virion proteins, a polypeptide with a molecular weight of 11,000 (11K polypeptide). We identified the gene for this polypeptide by sequence analysis of the radioactively labeled 11K polypeptide isolated from ts1 virions and comparison of this sequence with the nucleotide sequence of the adenovirus type 2 genome. The 11K polypeptide was encoded by an open reading frame of 80 residues located between nucleotides 17,676 and 17,915 in late transcription region 2 of adenovirus type 2; the initiating methionine residue was removed leaving a 79-residue product. The late transcription region 2 that encoded the 79-residue polypeptide (11K) was arginine rich (21%) and had a predicted molecular weight of 8,715. It was cleaved by the viral endoprotease to give two products which comigrated on sodium dodecyl sulfate-polyacrylamide gels as virion polypeptide X. Our data suggest that additional cleavage of the carboxy-terminal 48-residue fragment generates a 19-amino-acid fragment with the amino acid composition of mu (K. Hosokawa and M. T. Sung, J. Virol. 17:924-934, 1976).
Insights
Researchers identified a novel 11,000 molecular weight polypeptide in adenovirus type 2. This 79-residue polypeptide, encoded by late transcription region 2, is processed by viral proteases, suggesting a role in virion structure or function.
Area of Science:
- Virology
- Molecular Biology
- Protein Chemistry
Background:
- Nucleoprotein complexes from infected cells or ts1 virions contain an 11,000 molecular weight (11K) polypeptide.
- This polypeptide is present in addition to known virion proteins.
Purpose of the Study:
- To identify the gene encoding the 11K polypeptide.
- To characterize the properties and processing of the 11K polypeptide.
Main Methods:
- Sequence analysis of radioactively labeled 11K polypeptide isolated from ts1 virions.
- Comparison of the polypeptide sequence with the adenovirus type 2 genome sequence.
- Analysis of polypeptide cleavage by viral endoprotease.
Main Results:
- The 11K polypeptide is encoded by an 80-residue open reading frame (nucleotides 17,676-17,915) in adenovirus type 2 late transcription region 2.
- The mature polypeptide has 79 residues, is arginine-rich (21%), and has a predicted molecular weight of 8,715.
- Cleavage by viral endoprotease produces two products, comigrating as virion polypeptide X, with further cleavage potentially generating a mu fragment.
Conclusions:
- The 11K polypeptide is a distinct viral protein encoded within late transcription region 2 of adenovirus type 2.
- Its processing by viral proteases suggests a role in virion maturation or structure.
- The data indicate a complex proteolytic processing pathway for this polypeptide.