Type 1 ribosome-inactivating proteins from Phytolacca dioica L. leaves: differential seasonal and age expression, and cellular localization.
The expression of type 1 ribosome-inactivating proteins (RIPs) in Phytolacca dioica L. leaves was investigated. Fully expanded leaves of young P. dioica plants (up to 3 years old) expressed two novel RIPs, dioicin 1 and dioicin 2. The former was also found in developing leaves from adult P. dioica within about two and a half weeks after leaf development, and the latter continuously synthesized, with no seasonal or ontogenetic constraint. Fully expanded leaves from adult P. dioica expressed four RIPs (PD-Ls1-4) exhibiting seasonal variation. RIPs were localized in the extracellular space, in the vacuole and in the Golgi apparatus of mesophyll cells. Dioicin 1 and dioicin 2 showed rRNA N-beta-glycosidase activity and displayed the following properties, respectively: (1) Mr values of 30,047.00 and 29,910.00, (2) pIs of 8.74 and 9.37, and (3) IC(50) values of 19.74 (0.658 nM) and 6.85 ng/mL (0.229 nM). Furthermore, they showed adenine polynucleotide glycosylase activity and nicked pBR322 dsDNA. The amino acid sequence of dioicin 2 had 266 amino acid residues, and the highest percentage identity (81.6%) and similarity (84.6%) with PAP-II from Phytolacca americana, while its identity with other RIPs from Phytolaccaceae was around 40%.
Parente
Augusto
A
Dipartimento di Scienze della Vita, Seconda Università di Napoli, Caserta, Italy. augusto.parente@unina2.it
Conforto
Barbara
B
Di Maro
Antimo
A
Chambery
Angela
A
De Luca
Paolo
P
Bolognesi
Andrea
A
Iriti
Marcello
M
Faoro
Franco
F
D000595:Amino Acid Sequence; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D029603:Phytolacca / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D054789:Ribosome Inactivating Proteins, Type 1 / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012621:Seasons; D016415:Sequence Alignment; D013997:Time Factors
D054789:Ribosome Inactivating Proteins, Type 1; D003545:Cysteine