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Light-signalling pathways leading to the co-ordinated expression of HEMA1 and Lhcb during chloroplast development in Arabidopsis thaliana

Light-signalling pathways leading to the co-ordinated expression of HEMA1 and Lhcb during chloroplast development in Arabidopsis thaliana
Light-signalling pathways leading to the co-ordinated expression of HEMA1 and Lhcb during chloroplast development in Arabidopsis thaliana
During de-etiolation, the co-ordinated synthesis of chlorophyll and the chlorophyll a/b-binding proteins is critical to the development of functional light-harvesting complexes. To understand how this co-ordination is achieved, we have made a detailed study of the light-regulated signalling pathways mediating the expression of the HEMA1 and Lhcb genes encoding glutamyl-tRNA reductase, the first committed enzyme of 5-aminolaevulinic acid formation, and chlorophyll a/b-binding proteins, respectively. To do this, we have screened 7 photoreceptor and 12 light-signalling mutants of Arabidopsis thaliana L. for induction of HEMA1 and Lhcb expression in continuous red, far-red and blue light and following a red pulse. We have categorised these mutants into two groups. The phyA, phyB, phyAphyB, cry1, cry2, cop1, det1, poc1, eid1, and far1 mutations lead to diverse effects on the light regulation of HEMA1, but affect Lhcb expression to a similar degree. The hy1, hy2, hy5, fin219, fhy1, fhy3, spa1, ndpk2, and pat1 mutants also affect light regulation of both HEMA1 and Lhcb expression, but with differences in the relative magnitude of the two responses. The fhy1 and fhy3 mutants show the most significant differences in light regulation between the two genes, with both showing a strong inhibition of HEMA1 expression under continuous red light. These results demonstrate that co-ordinated regulation of HEMA1 and Lhcb is largely achieved through parallel light regulation mediated by shared phytochrome- and crytochrome-signalling pathways. However, glutamyl-tRNA reductase is also required for the synthesis of other tetrapyrroles and this dual role may account for the observed differences in these light-signalling pathways.
aminolaevulinic acid, glutamyl-tRNA reductase, haem and chlorophyll synthesis, light regulation of gene expression, light-harvesting proteins
0960-7412
549-559
McCormac, Alex C.
41fd08ca-de17-4563-a1f8-d35e1f6c0e20
Terry, Matthew J.
a8c2cd6b-8d35-4053-8d77-3841c2427c3b
McCormac, Alex C.
41fd08ca-de17-4563-a1f8-d35e1f6c0e20
Terry, Matthew J.
a8c2cd6b-8d35-4053-8d77-3841c2427c3b

McCormac, Alex C. and Terry, Matthew J. (2002) Light-signalling pathways leading to the co-ordinated expression of HEMA1 and Lhcb during chloroplast development in Arabidopsis thaliana. The Plant Journal, 32 (4), 549-559. (doi:10.1046/j.1365-313X.2002.01443.x).

Record type: Article

Abstract

During de-etiolation, the co-ordinated synthesis of chlorophyll and the chlorophyll a/b-binding proteins is critical to the development of functional light-harvesting complexes. To understand how this co-ordination is achieved, we have made a detailed study of the light-regulated signalling pathways mediating the expression of the HEMA1 and Lhcb genes encoding glutamyl-tRNA reductase, the first committed enzyme of 5-aminolaevulinic acid formation, and chlorophyll a/b-binding proteins, respectively. To do this, we have screened 7 photoreceptor and 12 light-signalling mutants of Arabidopsis thaliana L. for induction of HEMA1 and Lhcb expression in continuous red, far-red and blue light and following a red pulse. We have categorised these mutants into two groups. The phyA, phyB, phyAphyB, cry1, cry2, cop1, det1, poc1, eid1, and far1 mutations lead to diverse effects on the light regulation of HEMA1, but affect Lhcb expression to a similar degree. The hy1, hy2, hy5, fin219, fhy1, fhy3, spa1, ndpk2, and pat1 mutants also affect light regulation of both HEMA1 and Lhcb expression, but with differences in the relative magnitude of the two responses. The fhy1 and fhy3 mutants show the most significant differences in light regulation between the two genes, with both showing a strong inhibition of HEMA1 expression under continuous red light. These results demonstrate that co-ordinated regulation of HEMA1 and Lhcb is largely achieved through parallel light regulation mediated by shared phytochrome- and crytochrome-signalling pathways. However, glutamyl-tRNA reductase is also required for the synthesis of other tetrapyrroles and this dual role may account for the observed differences in these light-signalling pathways.

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Submitted date: 19 July 2002
Published date: November 2002
Keywords: aminolaevulinic acid, glutamyl-tRNA reductase, haem and chlorophyll synthesis, light regulation of gene expression, light-harvesting proteins

Identifiers

Local EPrints ID: 37638
URI: http://eprints.soton.ac.uk/id/eprint/37638
ISSN: 0960-7412
PURE UUID: 24cd77e9-011f-494c-af88-d6d37b75c027
ORCID for Matthew J. Terry: ORCID iD orcid.org/0000-0001-5002-2708

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Date deposited: 25 May 2006
Last modified: 16 Mar 2024 02:52

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Author: Alex C. McCormac

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