Molecular Cloning and Functional Expression of a Water-soluble Chlorophyll Protein, a Putative Carrier of Chlorophyll Molecules in Cauliflower

Abstract

A water-soluble chlorophyll protein (WSCP) 1 in Brassicaceae plants has been purified from Lepidium virginicum (1), Brassica nigra (wild mustard) (1), Brassica oleracea var. botrys (cauliflower) (2, 3), Brassica oleracea var. gemmifera (Brussels sprouts) (4), and Brassica napus var.

Structural Mechanism and Photoprotective Function of Water-soluble Chlorophyll-binding Protein

“…Furthermore, the recombinant apo-WSCP was able to remove Chl from the thylakoid membrane in vitro and organize the tetrameric WSCPChl complex (3). The absorption spectrum of the reconstituted complex is very similar to that of the native WSCP-Chl complex purified from fresh leaves (1,3).…”

“…Botrys) and Chl or its derivatives showed that the central Mg 2ϩ ion and the phytyl tail of Chl were essential for protein-pigment binding and tetrameric assembly, respectively (1). Furthermore, the recombinant apo-WSCP was able to remove Chl from the thylakoid membrane in vitro and organize the tetrameric WSCPChl complex (3). The absorption spectrum of the reconstituted complex is very similar to that of the native WSCP-Chl complex purified from fresh leaves (1,3).…”

“…The class-II WSCPs (hereafter referred to as "WSCPs") are water-soluble proteins of ϳ20 kDa, which form a tetrameric assembly upon binding Chl molecules with a Chl-to-protein ratio of one or less, and exhibit high thermal and photostability (1,3). The physiological function of WSCPs is still not known.…”

“…Photodynamic damage including the oxidative decomposition of Chl itself can be propagated by the singlet oxygen species, giving rise to radical oxygen species in vivo as well as in vitro (10,11). The risk of radical oxygen species generation in the thylakoid membrane is usually diminished by non-photochemical quenching by carotenoids, which are adjacent to Chl molecules in virtually all Chl-containing complexes and quench both the 3 Chl and the singlet oxygen (12,13). In view of this, one would expect that the WSCP-Chl complex also contains carotenoids to avoid the risk of radical oxygen species generation.…”

Identification of genes encoding photoconvertible (Class I) water-soluble chlorophyll-binding proteins from Chenopodium ficifolium

“…[18][19][20][21][22][23] Furthermore, various molecular genetic analyses on recombinant Class II WSCPs have been performed. 18,[20][21][22][23][24][25][26][27][28][29][30][31][32] On the other hand, CaWSCP is the only gene encoding a Class I WSCP identified to date and few studies on the molecular genetics of the protein have been performed thus far. 33,34) Identification of novel genes encoding Class I WSCPs is essential for understanding the molecular diversity of the protein.…”