Multiple Introns in a Conjugation-specific Gene from Tetrahymena Thermophila

Overview

Journal Nucleic Acids Res

Publisher Oxford University Press

Specialty Biochemistry

Date 1988 Mar 25

PMID 3357771

Citations 5

Authors

D W Martindale

F M TAYLOR

Affiliations

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Abstract

Multiple introns have been found in a gene from a ciliated protozoan. This Tetrahymena thermophila gene (cnjB) is large (7.5 kb mRNA) and active only during conjugation, the organism's sexual cycle. Six introns ranging in size from 62 bp to 676 bp were found when we sequenced a 3.1 kb segment of the cnjB gene together with its corresponding cDNA. We estimate, by extrapolation of our current data, a total of approximately 30 introns in this gene with a total gene size (introns plus exons) of 15 kb or more. The number of introns is surprising given the scarcity of introns in ciliate genes examined to date. Our findings constitute the first example of multiple introns in a ciliate gene. Having the sequence of several introns has allowed us to construct consensus sequences for T. thermophila mRNA introns. The 5' and 3' intron junctions resemble those of general nuclear mRNA (GT/AG rule is followed) but differences are seen. In particular, stretches of 10 or more adenines and thymines are found adjacent to the conserved GT and AGs at the junctions. Unusual aspects of the coding region of this gene are discussed.

Citing Articles

Retroviral-type zinc fingers and glycine-rich repeats in a protein encoded by cnjB, a Tetrahymena gene active during meiosis.

TAYLOR F, Martindale D Nucleic Acids Res. 1993; 21(19):4610-4.

PMID: 8233798 PMC: 311198. DOI: 10.1093/nar/21.19.4610.

The DNA of ciliated protozoa.

Prescott D Microbiol Rev. 1994; 58(2):233-67.

PMID: 8078435 PMC: 372963. DOI: 10.1128/mr.58.2.233-267.1994.

Isolation and complete sequence of the yeast isoleucyl-tRNA synthetase gene (ILS1).

Martindale D, Gu Z, Csank C Curr Genet. 1989; 15(2):99-106.

PMID: 2663194 DOI: 10.1007/BF00435455.

Nuclear pre-mRNA introns: analysis and comparison of intron sequences from Tetrahymena thermophila and other eukaryotes.

Csank C, TAYLOR F, Martindale D Nucleic Acids Res. 1990; 18(17):5133-41.

PMID: 2402440 PMC: 332134. DOI: 10.1093/nar/18.17.5133.

A conjugation-specific gene (cnjC) from Tetrahymena encodes a protein homologous to yeast RNA polymerase subunits (RPB3, RPC40) and similar to a portion of the prokaryotic RNA polymerase alpha subunit (rpoA).

Martindale D Nucleic Acids Res. 1990; 18(10):2953-60.

PMID: 2112240 PMC: 330824. DOI: 10.1093/nar/18.10.2953.

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