A Chlamydomonas protein that binds single-stranded G-strand telomere DNA

EMBO J. 1994 Aug 1;13(15):3648-58.

Abstract

We have identified a protein in Chlamydomonas reinhardtii cell extracts that specifically binds the single-stranded (ss) Chlamydomonas G-strand telomere sequence (TTTTAGGG)n. This protein, called G-strand binding protein (GBP), binds DNA with two or more ss TTTTAGGG repeats. A single polypeptide (M(r) 34 kDa) in Chlamydomonas extracts binds (TTTTAGGG)n, and a cDNA encoding this G-strand binding protein was identified by its expression of a G-strand binding activity. The cDNA (GBP1) sequence predicts a protein product (Gbp1p) that includes two domains with extensive homology to RNA recognition motifs (RRMs) and a region rich in glycine, alanine and arginine. Antibody raised against a peptide within Gbp1p reacted with both the 34 kDa polypeptide and bound G-strand DNA-protein complexes in gel retardation assays, indicating that GBP1 encodes GBP. Unlike vertebrate heteronuclear ribonucleoproteins, GBP does not bind the cognate telomere RNA sequence UUUUAGGG in gel retardation, North-Western or competition assays. Thus, GBP is a new type of candidate telomere binding protein that binds, in vitro, to ss G-strand telomere DNA, the primer for telomerase, and has domains that have homology to RNA binding domains in other proteins.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Chlamydomonas reinhardtii / genetics
  • Chlamydomonas reinhardtii / metabolism*
  • Cloning, Molecular
  • Consensus Sequence
  • DNA, Complementary
  • DNA, Protozoan / genetics
  • DNA, Protozoan / metabolism
  • DNA, Single-Stranded / genetics
  • DNA, Single-Stranded / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / isolation & purification
  • DNA-Binding Proteins / metabolism*
  • GTP-Binding Proteins*
  • Genes, Protozoan / genetics*
  • Molecular Sequence Data
  • Plant Proteins
  • Protozoan Proteins / genetics
  • Protozoan Proteins / isolation & purification
  • Protozoan Proteins / metabolism*
  • RNA, Messenger / analysis
  • RNA, Messenger / metabolism
  • RNA, Protozoan / analysis
  • RNA, Protozoan / metabolism
  • Repetitive Sequences, Nucleic Acid / genetics
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Telomere / metabolism

Substances

  • DNA, Complementary
  • DNA, Protozoan
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • GBP1 protein, Chlamydomonas
  • Plant Proteins
  • Protozoan Proteins
  • RNA, Messenger
  • RNA, Protozoan
  • GTP-Binding Proteins

Associated data

  • GENBANK/U10442