Primary structure and molecular modeling of mistletoe lectin I from Viscum album.
The first three-dimensional structure of the ribosome inactivating protein mistletoe lectin I (ML-I) from Viscum album has been modeled on the basis of the X-ray structure of castor bean ricin from Ricinus communis. The relative high sequence homology and conserved secondary structure enabled accurate modeling. The 196 sequence changes between ML-I and ricin could be accomodated with only little pertubation in the main chain folding. A close comparison of the primary structures of ML-I and ricin is given and the effects of the sequence changes are elucidated on the basis of the modeled three-dimensional structure. Differences have been identified in the vicinity of the active site, in the high affinity galactose binding site and in the interface between the A and B chains, which might account for the reduced cytotoxicity of ML-I.
Eschenburg
S
S
University Hospital c/o DESY, Building 22a, Notkestrasse 85, Hamburg, 22603, Germany.
Krauspenhaar
R
R
Mikhailov
A
A
Stoeva
S
S
Betzel
C
C
Voelter
W
W
D000595:Amino Acid Sequence; D001665:Binding Sites; D005690:Galactose / Q000378:metabolism; D037102:Lectins / Q000737:chemistry* / Q000235:genetics* / Q000633:toxicity; D014784:Mistletoe / Q000737:chemistry / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D037121:Plant Lectins; D028321:Plant Preparations; D010940:Plant Proteins; D010946:Plants, Medicinal; D011487:Protein Conformation; D054790:Ribosome Inactivating Proteins, Type 2; D012276:Ricin / Q000737:chemistry; D014118:Toxins, Biological / Q000737:chemistry* / Q000235:genetics* / Q000633:toxicity
D037102:Lectins; D037121:Plant Lectins; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C488862:mistletoe lectin I; C009674:ribosome inactivating protein, Viscum; D012276:Ricin; D005690:Galactose