Structural characterization and comparative modeling of PD-Ls 1-3, type 1 ribosome-inactivating proteins from summer leaves of Phytolacca dioica L.
The amino acid sequence and glycan structure of PD-L1, PD-L2 and PD-L3, type 1 ribosome-inactivating proteins isolated from Phytolacca dioica L. leaves, were determined using a combined approach based on peptide mapping, Edman degradation and ESI-Q-TOF MS in precursor ion discovery mode. The comparative analysis of the 261 amino acid residue sequences showed that PD-L1 and PD-L2 have identical primary structure, as it is the case of PD-L3 and PD-L4. Furthermore, the primary structure of PD-Ls 1-2 and PD-Ls 3-4 have 81.6% identity (85.1% similarity). The ESI-Q-TOF MS analysis confirmed that PD-Ls 1-3 were glycosylated at different sites. In particular, PD-L1 contained three glycidic chains with the well known paucidomannosidic structure (Man)(3) (GlcNAc)(2) (Fuc)(1) (Xyl)(1) linked to Asn10, Asn43 and Asn255. PD-L2 was glycosylated at Asn10 and Asn43, and PD-L3 was glycosylated only at Asn10. PD-L4 was confirmed to be not glycosylated. Despite an overall high structural similarity, the comparative modeling of PD-L1, PD-L2, PD-L3 and PD-L4 has shown potential influences of the glycidic chains on their adenine polynucleotide glycosylase activity on different substrates.
Di Maro
Antimo
A
Dipartimento di Scienze della Vita, Seconda Università degli Studi di Napoli, Via Vivaldi 43, I-81100 Caserta, Italy. antimo.dimaro@unina2.it
Chambery
Angela
A
Carafa
Vincenzo
V
Costantini
Susan
S
Colonna
Giovanni
G
Parente
Augusto
A
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D017124:Conserved Sequence; D017343:Genes, Plant; D006031:Glycosylation; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D029603:Phytolacca / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D054788:Ribosome Inactivating Proteins / Q000737:chemistry / Q000378:metabolism*; D012621:Seasons; D017386:Sequence Homology, Amino Acid
D010940:Plant Proteins; D054788:Ribosome Inactivating Proteins