title: Cysteine-2 and Cys30 are essential for chlorophyll-binding activity of the water-soluble chlorophyll-binding protein (WSCP) of Chenopodium album.
abstract: Chenopodium album has a non-photosynthetic chlorophyll protein known as the water-soluble chlorophyll (Chl)-binding protein (WSCP). The C. album WSCP (CaWSCP) is able to photoconvert the chlorin skeleton of Chl a into a bacteriochlorin-like skeleton. Reducing reagents such as β-mercaptoethanol or dithiothreitol inhibit photoconversion, indicating that S-S bridge(s) in CaWSCP are quite important for it. Recently, we found that the mature region of CaWSCP contains five cysteine residues; Cys2, Cys30, Cys48, Cys63, and Cys144. To identify which cysteine residues are involved in the photoconversion, we generated five mutants (C2S, C30S, C48S, C63S, and C144S) by site-directed mutagenesis. Interestingly, C48S, C63S, and C144S mutants showed the same Chl-binding activity and photoconvertibility as those of the recombinant wild-type CaWSCP-His, while the C2S and C30S mutants completely lost Chl-binding activity. Our findings indicated that the S-S bridge between Cys2 and Cys30 in each CaWSCP subunit is essential for Chl-binding activity.
authors: a Department of Biomolecular Science , Toho University , Funabashi , Japan.
authors: Shigekazu
authors: S
authors: Takahashi
authors: Yumiko
authors: Y
authors: Seki
authors: Akira
authors: A
authors: Uchida
authors: Katsumi
authors: K
authors: Nakayama
authors: Hiroyuki
authors: H
authors: Satoh
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D027463:Chenopodium album / Q000737:chemistry / Q000502:physiology*; D061146:Chlorophyll Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D012995:Solubility; D014867:Water / Q000737:chemistry*
chemical_list: D061146:Chlorophyll Binding Proteins; D014867:Water; D003545:Cysteine
keywords: Chenopodium album; DUF538; chlorophyll; photoconversion; water-soluble chlorophyll-binding protein