The germ line limited M element of Tetrahymena is targeted for elimination from the somatic genome by a homology-dependent mechanism

Christina A. Kowalczyk, Alissa M. Anderson, Maria Arce-Larreta, Douglas L. Chalker

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

A RNA interference (RNAi) like mechanism is involved in elimination of thousands of DNA segments from the developing somatic macronucleus of Tetrahymena, yet how specific internal eliminated sequences (IESs) are recognized remains to be fully elucidated. To define requirements for DNA rearrangement, we performed mutagenesis of the M element, a well-studied IES. While sequences within the macronucleus-retained DNA are known to determine the excision boundaries, we show that sequences internal to these boundaries are required to promote this IES's rearrangement. However, this element does not contain any specific sequence required in cis as removal of its entire left or right side was insufficient to abolish all rearrangement. Instead, rearrangement efficiency correlated with the overall size of the M element sequence within a given construct, with a lower limit of nearly 300 bp. Also, the observed minimal region necessary to epigenetically block excision supports this size limit. Truncated M element constructs that exhibited impaired rearrangement still showed full transcriptional activity, which suggests that their defect was due to inefficient recognition. This study indicates that IESs are targeted for elimination upon their recognition by homologous small RNAs and further supports the idea that DNA elimination is a RNAi-related mechanism involved in genome surveillance.

Original languageEnglish
Pages (from-to)5778-5789
Number of pages12
JournalNucleic acids research
Volume34
Issue number20
DOIs
StatePublished - Nov 2006

Fingerprint

Dive into the research topics of 'The germ line limited M element of Tetrahymena is targeted for elimination from the somatic genome by a homology-dependent mechanism'. Together they form a unique fingerprint.

Cite this