The X gene of hepatitis B virus shows a high level stimulation of the Rous sarcoma virus long terminal repeat in the methylotropic yeast, Pichia pastoris

Sunil K. Lal, Vijay Kumar

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1 Citation (Scopus)


In order to study the transactivational property of the X gene in the methylotropic yeast Pichia pastoris, a Rous sarcoma virus-chloramphenicol acetyltransferase (RSV-CAT) cassette was co-transformed and integrated into the host yeast strain as a reporter which showed an overwhelming CAT activity. Immunoprecipitation of the yeast cell extracts with an X-specific monoclonal antibody, however, showed a low level expression of the X gene. Therefore besides a trans-effect of the X protein, the enhanced reporter activity could be a manifestation of a cis-effect of the X gene sequences also. Therefore, unlike the transactivation studies with X gene in animal cells where limited functional activity is observed, P. pastoris appears to be an excellent system to study cis- and trans-aspects of gene regulation by the X gene. Copyright (C) 1999 Federation of European Biochemical Societies.

Original languageEnglish
Pages (from-to)108-112
Number of pages5
JournalFEBS Letters
Issue number1
Publication statusPublished - 30 Jul 1999
Externally publishedYes


  • Heterologous gene expression
  • Pichia pastoris
  • Rous sarcoma virus long terminal repeat
  • Transactivation by HBV X gene product

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