Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses

R. B. Pepinsky, I. A. Papayannopoulos, E. P. Chow, N. K. Krishna, Rebecca Craven, V. M. Vogt

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Abstract

The CA (capsid) protein of avian sarcoma and leukemia viruses occurs in multiple species. Only one form has been previously characterized biochemically. We have now determined that the mature CA protein of avian sarcoma and leukemia viruses exists as three species with different C termini, ending in amino acid residues A-476, A-478, and M-479 of the Gag precursor, respectively. These structures were deduced from a combination of cyanogen bromide peptide mapping, sequence analysis of tryptic peptides, and electrospray mass spectrometry. The three forms of CA were detected in the same ratios in Rous sarcoma virus and avian myeloblastosis virus and therefore are likely to represent a common feature of members of this genus of avian retroviruses. The only previously reported CA species, CA(M-479), accounts for only about 36% of the total CA protein, while CA(A-476) and CA(A-478) account for 55 and 9%, respectively. From the analysis of peptides cleaved in vitro by PR, the viral protease, we infer that the cleavage site between A-476 and A-477 not only is recognized by PR but is the preferred site. We were unable to determine if A-478/A-479 is a cleavage site for PR or alternatively if CA(A-478) results from further processing of CA(M-479) by a carboxypeptidase. To study the biological significance of residues A-477 to M-479, we constructed genetically altered viruses in which deletions removed either residues 477 to 479 or 477 to 488. The resulting virus particles appeared to assembly with normal efficiencies, but the latter mutant showed slowed proteolytic processing. Neither of the mutants was infectious.

Original languageEnglish (US)
Pages (from-to)6430-6438
Number of pages9
JournalJournal of Virology
Volume69
Issue number10
StatePublished - 1995

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avian sarcoma
Avian Sarcoma Viruses
capsid
Capsid
Capsid Proteins
coat proteins
leukemia
Leukemia
viruses
Avian myeloblastosis virus
Retroviridae
Avian Myeloblastosis Virus
peptides
Rous sarcoma virus
peptide mapping
cyanogen
Carboxypeptidases
carboxypeptidases
Cyanogen Bromide
mutants

All Science Journal Classification (ASJC) codes

  • Immunology

Cite this

Pepinsky, R. B., Papayannopoulos, I. A., Chow, E. P., Krishna, N. K., Craven, R., & Vogt, V. M. (1995). Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses. Journal of Virology, 69(10), 6430-6438.
Pepinsky, R. B. ; Papayannopoulos, I. A. ; Chow, E. P. ; Krishna, N. K. ; Craven, Rebecca ; Vogt, V. M. / Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses. In: Journal of Virology. 1995 ; Vol. 69, No. 10. pp. 6430-6438.
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abstract = "The CA (capsid) protein of avian sarcoma and leukemia viruses occurs in multiple species. Only one form has been previously characterized biochemically. We have now determined that the mature CA protein of avian sarcoma and leukemia viruses exists as three species with different C termini, ending in amino acid residues A-476, A-478, and M-479 of the Gag precursor, respectively. These structures were deduced from a combination of cyanogen bromide peptide mapping, sequence analysis of tryptic peptides, and electrospray mass spectrometry. The three forms of CA were detected in the same ratios in Rous sarcoma virus and avian myeloblastosis virus and therefore are likely to represent a common feature of members of this genus of avian retroviruses. The only previously reported CA species, CA(M-479), accounts for only about 36{\%} of the total CA protein, while CA(A-476) and CA(A-478) account for 55 and 9{\%}, respectively. From the analysis of peptides cleaved in vitro by PR, the viral protease, we infer that the cleavage site between A-476 and A-477 not only is recognized by PR but is the preferred site. We were unable to determine if A-478/A-479 is a cleavage site for PR or alternatively if CA(A-478) results from further processing of CA(M-479) by a carboxypeptidase. To study the biological significance of residues A-477 to M-479, we constructed genetically altered viruses in which deletions removed either residues 477 to 479 or 477 to 488. The resulting virus particles appeared to assembly with normal efficiencies, but the latter mutant showed slowed proteolytic processing. Neither of the mutants was infectious.",
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Pepinsky, RB, Papayannopoulos, IA, Chow, EP, Krishna, NK, Craven, R & Vogt, VM 1995, 'Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses', Journal of Virology, vol. 69, no. 10, pp. 6430-6438.

Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses. / Pepinsky, R. B.; Papayannopoulos, I. A.; Chow, E. P.; Krishna, N. K.; Craven, Rebecca; Vogt, V. M.

In: Journal of Virology, Vol. 69, No. 10, 1995, p. 6430-6438.

Research output: Contribution to journalArticle

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T1 - Differential proteolytic processing leads to multiple forms of the CA protein in avian sarcoma and leukemia viruses

AU - Pepinsky, R. B.

AU - Papayannopoulos, I. A.

AU - Chow, E. P.

AU - Krishna, N. K.

AU - Craven, Rebecca

AU - Vogt, V. M.

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Y1 - 1995

N2 - The CA (capsid) protein of avian sarcoma and leukemia viruses occurs in multiple species. Only one form has been previously characterized biochemically. We have now determined that the mature CA protein of avian sarcoma and leukemia viruses exists as three species with different C termini, ending in amino acid residues A-476, A-478, and M-479 of the Gag precursor, respectively. These structures were deduced from a combination of cyanogen bromide peptide mapping, sequence analysis of tryptic peptides, and electrospray mass spectrometry. The three forms of CA were detected in the same ratios in Rous sarcoma virus and avian myeloblastosis virus and therefore are likely to represent a common feature of members of this genus of avian retroviruses. The only previously reported CA species, CA(M-479), accounts for only about 36% of the total CA protein, while CA(A-476) and CA(A-478) account for 55 and 9%, respectively. From the analysis of peptides cleaved in vitro by PR, the viral protease, we infer that the cleavage site between A-476 and A-477 not only is recognized by PR but is the preferred site. We were unable to determine if A-478/A-479 is a cleavage site for PR or alternatively if CA(A-478) results from further processing of CA(M-479) by a carboxypeptidase. To study the biological significance of residues A-477 to M-479, we constructed genetically altered viruses in which deletions removed either residues 477 to 479 or 477 to 488. The resulting virus particles appeared to assembly with normal efficiencies, but the latter mutant showed slowed proteolytic processing. Neither of the mutants was infectious.

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