Reference "Structure and differential expression of two maize ferritin genes in response to iron and abscisic acid"

Reference ID

7460

Title

Structure and differential expression of two maize ferritin genes in response to iron and abscisic acid

Source

European journal of biochemistry / FEBS, 1995, vol. 231, pp. 609-619

Authors (5)

Fobis-Loisy-I	Loridon-K
Lobreaux-S	Lebrun-M
Briat-J-F

Abstract

In plants, synthesis of the iron-storage protein ferritin in response to iron is
not regulated at the translational level; this is in contrast to ferritin
synthesis in animals. Part of the response is mediated through a transduction
pathway which involves the plant hormone abscisic acid. In this work, we report
the cloning and sequencing of two maize ferritin genes (ZmFer1 and ZmFer2)
coding for members of the two ferritin mRNA subclasses, FM1 and FM2,
respectively. Although plant and animal ferritins are closely related proteins,
a major difference is observed between the organisation of the genes. Both maize
ferritin genes are organised as eight exons and seven introns, the positions of
which are identical within the two genes, while animal ferritin genes are
interrupted by three introns, at positions different from those found in maize
genes. Sequence divergence between the 3' untranslated regions of these genes
has allowed the use of specific probes to study the accumulation of FM1 and FM2
transcripts in response to various environmental cues. Such probes have shown
that FM1 and FM2 transcripts accumulate with differential kinetics in response
to iron; FM1 mRNA accumulate earlier than FM2 mRNA and only FM2 transcripts
accumulate in response to exogenous abscisic acid or water stress. Mapping of
the transcriptional initiation region of these two genes defined their 5'
upstream regions and allowed a sequence comparison of their promoters, which
appeared highly divergent. This raises the possibility that the differential
accumulation of FM1 and FM2 mRNAs in response to iron, abscisic acid and drought
could be due to differential transcription of ZmFer1 and ZmFer2.