ISSN:
1573-5028
Keywords:
cis-acting elements
;
Lupinus angustifolius
;
nitrogen fixation
;
nodulin gene regulation
;
promoter analysis
;
trans-acting factors
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The promoter from the Lupinus angustifolius late nodulin gene, Nodulin-45, has been analysed to identify cis-elements and trans-acting factors. Various regions of the Nodulin-45 promoter, fused to the luciferase reporter gene, were introduced into Lotus roots using an Agrobacterium rhizogenes transformation procedure. The transgenic roots were then nodulated. The promoter region A (−172 to +13, relative to the transcription start site) was capable of directing low-level expression of the reporter gene and in a nodule-enhanced manner when compared to roots. The addition of region C (−676 to −345) resulted in a significant increase in the expression within the nodule, whilst a low level of root expression was maintained. The C region, which confers this high-level nodule expression, contains the nodule consensus motifs AAAGAT and CTCTT. When region C was ligated to a minimal promoter element from the unrelated asparaginase gene rather than the Nodulin-45 A region, nodule-enhanced expression was still apparent, but at a much lower level. Mutation of the AAAGAT element in this construct resulted in a further significant decrease of expression. Gel retardation assays revealed that a factor from lupin nodule nuclear extracts interacted with two sequences of the C region. The binding of the factor to both of these regions could be removed by the addition of an oligonucleotide containing the AT-rich binding site for the soybean factor NAT2. This suggests that the lupin factor identified here is a NAT2 homologue. No factor binding was observed to the AAAGAT or CTCTT elements present in the C region.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00019313
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