Abstract
To date, mobile Mu transposons and their autonomous regulator MuDR have been found only in the two known Mutator lines of maize and their immediate descendants. To gain insight into the origin, organization, and regulation of Mutator elements, we surveyed exotic maize and related species for cross-hybridization to MuDR. Some accessions of the mexican land race Zapalote chico contain one to several copies of full-length, unmethylated, and transcriptionally active MuDR-like elements plus non-autonomous Mu elements. The sequenced 5.0-kb MuDR-Zc element is 94.6% identical to MuDR, with only 20 amino acid changes in the 93-kD predicted protein encoded by mudrA and ten amino acid changes in the 23-kD predicted protein of mudrB. The terminal inverted repeat (TIR) A of MuDR-Zc is identical to standard MuDR; TIRB is 11.2% divergent from TIRA. In Zapalote chico, mudrA transcripts are very rare, while mudrB transcripts are as abundant as in Mutator lines with a few copies of MuDR. Zapalote chico lines with MuDR-like elements can trans-activate reporter alleles in inactive Mutator backgrounds; they match the characteristic increased forward mutation frequency of standard Mutator lines, but only after outcrossing to another line. Zapalote chico accessions that lack MuDR-like elements and the single copy MuDR a1-mum2 line produce few mutations. New mutants recovered from Zapalote chico are somatically stable.
Full Text
The Full Text of this article is available as a PDF (451.5 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Benito M. I., Walbot V. Characterization of the maize Mutator transposable element MURA transposase as a DNA-binding protein. Mol Cell Biol. 1997 Sep;17(9):5165–5175. doi: 10.1128/mcb.17.9.5165. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bennetzen J. L. The Mutator transposable element system of maize. Curr Top Microbiol Immunol. 1996;204:195–229. doi: 10.1007/978-3-642-79795-8_9. [DOI] [PubMed] [Google Scholar]
- Bennetzen J. L. Transposable element Mu1 is found in multiple copies only in Robertson's Mutator maize lines. J Mol Appl Genet. 1984;2(6):519–524. [PubMed] [Google Scholar]
- Berger P. B. New directions in research: report from the 10th International Conference on AIDS. CMAJ. 1995 Jun 15;152(12):1991–1995. [PMC free article] [PubMed] [Google Scholar]
- Capy P., Anxolabéhère D., Langin T. The strange phylogenies of transposable elements: are horizontal transfers the only explantation? Trends Genet. 1994 Jan;10(1):7–12. doi: 10.1016/0168-9525(94)90012-4. [DOI] [PubMed] [Google Scholar]
- Chandler V. L., Hardeman K. J. The Mu elements of Zea mays. Adv Genet. 1992;30:77–122. doi: 10.1016/s0065-2660(08)60319-3. [DOI] [PubMed] [Google Scholar]
- Chandler V. L., Talbert L. E., Raymond F. Sequence, genomic distribution and DNA modification of a Mu1 element from non-mutator maize stocks. Genetics. 1988 Aug;119(4):951–958. doi: 10.1093/genetics/119.4.951. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chandler V. L., Walbot V. DNA modification of a maize transposable element correlates with loss of activity. Proc Natl Acad Sci U S A. 1986 Mar;83(6):1767–1771. doi: 10.1073/pnas.83.6.1767. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chandler V., Rivin C., Walbot V. Stable non-mutator stocks of maize have sequences homologous to the Mu1 transposable element. Genetics. 1986 Nov;114(3):1007–1021. doi: 10.1093/genetics/114.3.1007. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chomet P., Lisch D., Hardeman K. J., Chandler V. L., Freeling M. Identification of a regulatory transposon that controls the Mutator transposable element system in maize. Genetics. 1991 Sep;129(1):261–270. doi: 10.1093/genetics/129.1.261. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Eisen J. A., Benito M. I., Walbot V. Sequence similarity of putative transposases links the maize Mutator autonomous element and a group of bacterial insertion sequences. Nucleic Acids Res. 1994 Jul 11;22(13):2634–2636. doi: 10.1093/nar/22.13.2634. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Feinberg A. P., Vogelstein B. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal Biochem. 1983 Jul 1;132(1):6–13. doi: 10.1016/0003-2697(83)90418-9. [DOI] [PubMed] [Google Scholar]
- Hershberger R. J., Benito M. I., Hardeman K. J., Warren C., Chandler V. L., Walbot V. Characterization of the major transcripts encoded by the regulatory MuDR transposable element of maize. Genetics. 1995 Jul;140(3):1087–1098. doi: 10.1093/genetics/140.3.1087. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hershberger R. J., Warren C. A., Walbot V. Mutator activity in maize correlates with the presence and expression of the Mu transposable element Mu9. Proc Natl Acad Sci U S A. 1991 Nov 15;88(22):10198–10202. doi: 10.1073/pnas.88.22.10198. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hsia A. P., Schnable P. S. DNA sequence analyses support the role of interrupted gap repair in the origin of internal deletions of the maize transposon, MuDR. Genetics. 1996 Feb;142(2):603–618. doi: 10.1093/genetics/142.2.603. [DOI] [PMC free article] [PubMed] [Google Scholar]
- James M. G., Scanlon M. J., Qin M., Robertson D. S., Myers A. M. DNA sequence and transcript analysis of transposon MuA2, a regulator of Mutator transposable element activity in maize. Plant Mol Biol. 1993 Mar;21(6):1181–1185. doi: 10.1007/BF00023614. [DOI] [PubMed] [Google Scholar]
- Joanin P., Hershberger R. J., Benito M. I., Walbot V. Sense and antisense transcripts of the maize MuDR regulatory transposon localized by in situ hybridization. Plant Mol Biol. 1997 Jan;33(1):23–36. doi: 10.1023/a:1005790129668. [DOI] [PubMed] [Google Scholar]
- Kloeckener-Gruissem B., Freeling M. Transposon-induced promoter scrambling: a mechanism for the evolution of new alleles. Proc Natl Acad Sci U S A. 1995 Mar 14;92(6):1836–1840. doi: 10.1073/pnas.92.6.1836. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lisch D., Chomet P., Freeling M. Genetic characterization of the Mutator system in maize: behavior and regulation of Mu transposons in a minimal line. Genetics. 1995 Apr;139(4):1777–1796. doi: 10.1093/genetics/139.4.1777. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Martienssen R., Baron A. Coordinate suppression of mutations caused by Robertson's mutator transposons in maize. Genetics. 1994 Mar;136(3):1157–1170. doi: 10.1093/genetics/136.3.1157. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Norrander J., Kempe T., Messing J. Construction of improved M13 vectors using oligodeoxynucleotide-directed mutagenesis. Gene. 1983 Dec;26(1):101–106. doi: 10.1016/0378-1119(83)90040-9. [DOI] [PubMed] [Google Scholar]
- Qin M. M., Robertson D. S., Ellingboe A. H. Cloning of the Mutator transposable element MuA2, a putative regulator of somatic mutability of the a1-Mum2 allele in maize. Genetics. 1991 Nov;129(3):845–854. doi: 10.1093/genetics/129.3.845. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Robertson D. S. Mutator activity in maize: timing of its activation in ontogeny. Science. 1981 Sep 25;213(4515):1515–1517. doi: 10.1126/science.213.4515.1515. [DOI] [PubMed] [Google Scholar]
- Schnable P. S., Peterson P. A., Saedler H. The bz-rcy allele of the Cy transposable element system of Zea mays contains a Mu-like element insertion. Mol Gen Genet. 1989 Jun;217(2-3):459–463. doi: 10.1007/BF02464917. [DOI] [PubMed] [Google Scholar]
- Schnable P. S., Peterson P. A. The Mutator-Related Cy Transposable Element of Zea Mays L. Behaves as a near-Mendelian Factor. Genetics. 1988 Oct;120(2):587–596. doi: 10.1093/genetics/120.2.587. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schwarz-Sommer Z., Gierl A., Cuypers H., Peterson P. A., Saedler H. Plant transposable elements generate the DNA sequence diversity needed in evolution. EMBO J. 1985 Mar;4(3):591–597. doi: 10.1002/j.1460-2075.1985.tb03671.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stapleton A. E., Walbot V. Flavonoids can protect maize DNA from the induction of ultraviolet radiation damage. Plant Physiol. 1994 Jul;105(3):881–889. doi: 10.1104/pp.105.3.881. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Talbert L. E., Patterson G. I., Chandler V. L. Mu transposable elements are structurally diverse and distributed throughout the genus Zea. J Mol Evol. 1989 Jul;29(1):28–39. doi: 10.1007/BF02106179. [DOI] [PubMed] [Google Scholar]
- Taylor L. P., Walbot V. Isolation and characterization of a 1.7-kb transposable element from a mutator line of maize. Genetics. 1987 Oct;117(2):297–307. doi: 10.1093/genetics/117.2.297. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walbot V. Inheritance of mutator activity in Zea mays as assayed by somatic instability of the bz2-mu1 allele. Genetics. 1986 Dec;114(4):1293–1312. doi: 10.1093/genetics/114.4.1293. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Walbot V. The Mutator transposable element family of maize. Genet Eng (N Y) 1991;13:1–37. doi: 10.1007/978-1-4615-3760-1_1. [DOI] [PubMed] [Google Scholar]
- Walbot V., Warren C. Regulation of Mu element copy number in maize lines with an active or inactive Mutator transposable element system. Mol Gen Genet. 1988 Jan;211(1):27–34. doi: 10.1007/BF00338389. [DOI] [PubMed] [Google Scholar]
- Wang L., Heinlein M., Kunze R. Methylation pattern of Activator transposase binding sites in maize endosperm. Plant Cell. 1996 Apr;8(4):747–758. doi: 10.1105/tpc.8.4.747. [DOI] [PMC free article] [PubMed] [Google Scholar]