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Molecular cloning of a carotenoid‐associated protein from Cucumis sativus corollas: homologous genes involved in carotenoid sequestration in chromoplasts
Author(s) -
Vishnevetsky Michael,
Ovadis Marianna,
Itzhaki Hanan,
Levy Maggie,
LibalWeksler Yael,
Adam Zach,
Vainstein Alexander
Publication year - 1996
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1996.10061111.x
Subject(s) - chromoplast , cucumis , plastid , biology , carotenoid , gene , chloroplast , complementary dna , botany , biochemistry
Summary Chromoplasts are carotenoid‐accumulating plastids found in the corollas and fruits of many higher plants. In most cases, the pigment in these plastids is accumulated with the aid of carotenoid‐associated proteins located within unique structures. This paper reports the isolation and characterization of the cDNA ( CHRC ) from Cucumis sativus corollas which encodes the chromoplast‐specific carotenoid‐associated protein CHRC. The transit peptide cleavage site was determined and, using a chloroplast uptake system, it is shown that CHRC can be post‐translationally targeted to these plastids where it is peripherally associated with thylakoids. Analysis of CHRC transcript level in Cucumis sativus revealed its temporal and tissue‐specific regulation: the transcript was detected only in corollas, where its level increased in parallel to flower development, peaking just before anthesis. CHRC shares significant homology (59%) with the gene coding for fibrillin — a protein in Capsicum annuum red fruits whose function is essentially identical to that of CHRC. A CHRC fragment including the potential active site of the protein was used as a probe in Northern blot analyses of floral and fruit tissues from various plants containing chromoplasts of different types: CHRC homologs of similar sizes were revealed in all cases. The existence of a group of homologous genes coding for chromoplast‐specific proteins which aid in the sequestration of carotenoids within specific structures is proposed.