Campus Units

Zoology, Molecular, Cellular and Developmental Biology, Genetics

Document Type

Article

Publication Version

Published Version

Publication Date

1994

Journal or Book Title

Nucleic Acids Research

Volume

22

Issue

21

First Page

4432

Last Page

4440

DOI

10.1093/nar/22.21.4432

Abstract

An origin of DNA replication has been mapped within the 5' non-transcribed spacer region of the amplified macronuclear rRNA genes (rDNA) of Tetrahymena thermophila. Mutations in 33 nt conserved AT-rich Type I repeat sequences located in the origin region cause defects in the replication and/or maintenance of amplified rDNA in vivo. Fe(ll)EDTA cleavage footprinting of restriction fragments containing the Type I repeat showed that most of the conserved nucleotides were protected by proteins in extracts of Tetrahymena cells. Two classes of proteins that bound the Type I repeat were identified and characterized using synthetic oligonucleotides in electrophoretic mobility shift assays. One of these, ds-TIBF, bound preferentially to duplex DNA and exhibited only moderate specificity for Type I repeat sequences. In contrast, a single-stranded DNA-binding protein, ssATIBF, specifically recognized the A-rich strand of the Type I repeat sequence. Deletion of the 5′ or 3′ borders of the conserved sequence significantly reduced binding of ssA-TIBF. The binding properties of ssATIBF, coupled with genetic evidence that Type I sequences function as c/s-acting rDNA replication control elements in vivo, suggest a possible role for ssA-TIBF in rDNA replication in Tetrahymena.

Comments

This article is from Nucleic Acids Research 22 (1994): 4432, doi: 10.1093/nar/22.21.4432. Posted with permission.

Copyright Owner

Oxford University Press

Language

en

File Format

application/pdf

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