Identification of three essential regions of hepatitis B virus X protein for trans-activation function

Oncogene. 1992 Mar;7(3):397-403.

Abstract

The X protein of hepatitis B virus (HBV) consists of 154 amino acids and trans-activates various cellular and viral promoters and enhancers. To investigate the essential amino acid sequences of X protein for trans-activation function, various mutations were introduced into the X open reading frame and analysed for trans-activation activity by chloramphenicol acetyltransferase assay. The amino acid sequences 46-52 (especially Pro-46, His-49 and His-52), 61-69 (especially Cys-61, Gly-67 to Pro-68 and Cys-69) and 132-139 (especially Phe-132, Cys-137 and His-139) of HBV X protein were found to be essential for the trans-activation function. These three sequences are included in the conserved amino acid sequences among hepadna virus X proteins. The first one could form a domain-like structure characteristic of histidine/aspartic acid requirement. The second and the third are homologous to the Kunitz domain of Kunitz-type serine protease inhibitors. The amino acids 5-27 region was found to make no positive contribution to the trans-activation function like the last 12 amino acids in the carboxy-terminal region [Takada, S. & Koike, K. (1990). Proc. Natl. Acad. Sci. USA, 87, 5628-5632]. From these findings, the trans-activation function of X protein appears to be dependent on at least two types of domain-like structures.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • DNA Mutational Analysis
  • Gene Expression
  • Hepatitis B virus / genetics*
  • Molecular Sequence Data
  • RNA, Messenger / genetics
  • Recombinant Proteins / metabolism
  • Sequence Alignment
  • Structure-Activity Relationship
  • Trans-Activators / chemistry*
  • Transcriptional Activation*
  • Transfection
  • Viral Regulatory and Accessory Proteins

Substances

  • RNA, Messenger
  • Recombinant Proteins
  • Trans-Activators
  • Viral Regulatory and Accessory Proteins
  • hepatitis B virus X protein