A novel chromodomain protein, pdd3p, associates with internal eliminated sequences during macronuclear development in Tetrahymena thermophila.

Abstract

Conversion of the germ line micronuclear genome into the genome of a somatic macronucleus in Tetrahymena thermophila requires several DNA rearrangement processes. These include (i) excision and subsequent elimination of several thousand internal eliminated sequences (IESs) scattered throughout the micronuclear genome and (ii) breakage of the micronuclear chromosomes into hundreds of DNA fragments, followed by de novo telomere addition to their ends. Chromosome breakage sequences (Cbs) that determine the sites of breakage and short regions of DNA adjacent to them are also eliminated. Both processes occur concomitantly in the developing macronucleus. Two stage-specific protein factors involved in germ line DNA elimination have been described previously. Pdd1p and Pdd2p (for programmed DNA degradation) physically associate with internal eliminated sequences in transient electron-dense structures in the developing macronucleus. Here, we report the purification, sequence analysis, and characterization of Pdd3p, a novel developmentally regulated, chromodomain-containing polypeptide. Pdd3p colocalizes with Pdd1p in the peripheral regions of DNA elimination structures, but is also found more internally. DNA cross-linked and immunoprecipitated with Pdd1p- or Pdd3p-specific antibodies is enriched in IESs, but not Cbs, suggesting that different protein factors are involved in elimination of these two groups of sequences.

• Authors: M A Nikiforov, M A Gorovsky, C D Allis
• Journal: Molecular and cellular biology (Mol Cell Biol) Vol. 20 Issue 11 Pg. 4128-34 (Jun 2000) ISSN: 0270-7306 [Print] United States
• PMID: 10805754 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• DNA, Protozoan
• DNA-Binding Proteins
• Nuclear Proteins
• PDD3 protein, Tetrahymena thermophila
• Pdd1 protein, Tetrahymena
• Phosphoproteins
• Protozoan Proteins

Topics

• Amino Acid Sequence
• Animals
• Base Sequence
• Cell Nucleus
• DNA, Protozoan (metabolism)
• DNA-Binding Proteins (genetics, isolation & purification, metabolism)
• Genome, Protozoan
• Molecular Sequence Data
• Nuclear Proteins (genetics, isolation & purification, metabolism)
• Phosphoproteins (metabolism)
• Protozoan Proteins (genetics, isolation & purification, metabolism)
• Sequence Homology, Amino Acid
• Tetrahymena thermophila (genetics, metabolism)