The budding yeast homolog of the human EBNA1-binding protein 2 (Ebp2p) is an essential nucleolar protein required for pre-rRNA processing

J Biol Chem. 2000 Sep 15;275(37):28764-73. doi: 10.1074/jbc.M000594200.

Abstract

The human EBP2 protein was found by two-hybrid analysis to interact with the Epstein-Barr virus nuclear antigen 1 (EBNA1). Homologs of human EBP2 can be found in Caenorhabditis elegans, Schizosaccharomyces pombe, and in Saccharomyces cerevisiae, and they all share a conserved 200-300-amino acid block of residues at their C termini. To understand the cellular function of EBP2, we have begun to study the protein in S. cerevisiae. The yeast Ebp2 protein contains N-terminal, nucleolar-associated KKE motifs, and deletion analysis reveals that the C-terminal conserved region is required for the activity of the protein. The EBP2 gene codes for an essential protein that localizes to the nucleolus. Temperature-sensitive ebp2-1 mutants become depleted of ribosomes and cease to divide after several generations at the restrictive temperature of 36 degrees C. This decline in ribosome levels is accompanied by a diminution in the levels of the 35 S-derived recombinant RNAs (rRNAs) (in particular the 25 S and 5.8 S rRNAs). Pulse-chase, Northern, and primer extension analysis of the rRNA biosynthetic pathway indicates that ebp2-1 mutants are defective in processing the 27 SA precursor into the 27 SB pre-rRNA.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / physiology*
  • Cell Nucleolus / chemistry*
  • Epstein-Barr Virus Nuclear Antigens / metabolism*
  • Fungal Proteins / physiology*
  • Humans
  • Molecular Sequence Data
  • RNA Precursors / metabolism*
  • RNA, Ribosomal / biosynthesis*
  • Saccharomyces cerevisiae / chemistry*

Substances

  • Carrier Proteins
  • Epstein-Barr Virus Nuclear Antigens
  • Fungal Proteins
  • RNA Precursors
  • RNA, Ribosomal