Duplication-dependent CG suppression of the seed storage protein genes of maize.
نویسندگان
چکیده
This study investigates the prevalence of CG and CNG suppression in single- vs. multicopy DNA regions of the maize genome. The analysis includes the single- and multicopy seed storage proteins (zeins), the miniature inverted-repeat transposable elements (MITEs), and long terminal repeat (LTR) retrotransposons. Zein genes are clustered on specific chromosomal regions, whereas MITEs and LTRs are dispersed in the genome. The multicopy zein genes are CG suppressed and exhibit large variations in CG suppression. The variation observed correlates with the extent of duplication each zein gene has undergone, indicating that gene duplication results in an increased turnover of cytosine residues. Alignment of individual zein genes confirms this observation and demonstrates that CG depletion results primarily from polarized C:T and G:A transition mutations from a less to a more extensively duplicated gene. In addition, transition mutations occur primarily in a CG or CNG context suggesting that CG suppression may result from deamination of methylated cytosine residues. Duplication-dependent CG depletion is likely to occur at other loci as duplicated MITEs and LTR elements, or elements inserted into duplicated gene regions, also exhibit CG depletion.
منابع مشابه
Divergent Transactivation of Maize Storage Protein Zein Genes by the Transcription Factors Opaque2 and OHPs
Maize transcription factors (TFs) opaque2 (O2) and the O2 heterodimerizing proteins (OHP1 and OHP2) originated from an ancient segmental duplication. The 22-kDa (z1C) and 19-kDa (z1A, z1B, and z1D) α-zeins are the most abundant storage proteins in maize endosperm. O2 is known to regulate α-zein gene expression, but its target motifs in the 19-kDa α-zein gene promoters have not been identified. ...
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عنوان ژورنال:
- Genetics
دوره 165 2 شماره
صفحات -
تاریخ انتشار 2003