ABSTRACT
The structure of a catalytically inactive RNase-related protein from Calystegia sepium (CalsepRRP) has been resolved by protein crystallography at a resolution of 2.05 A and an R factor of 20.74%. Although the protein is completely devoid of ribonuclease activity, it adopts the typical alpha + beta structure of non-base-specific RNases. Analysis of the structure revealed that two amino-acid substitutions in the 'active' P1 site, in combination with the less hydrophobic/aromatic character of the B1 base-recognition site and a completely disrupted B2 base-recognition site, might account for this complete lack of activity.
Subject(s)
Plant Proteins/chemistry , Amino Acid Sequence , Binding Sites , Crystallography, X-Ray , Models, Molecular , Molecular Sequence Data , Protein Structure, Secondary , Sequence AlignmentABSTRACT
The structure of the bark lectin RPbAI (isoform A4) from Robinia pseudoacacia has been determined by protein crystallography both in the free form and complexed with N-acetylgalactosamine. The free form is refined at 1.80 A resolution to an R-factor of 18.9% whereas the complexed structure has an R-factor of 19.7% at 2.05 A resolution. Both structures are compared to each other and to other available legume lectin structures. The polypeptide chains of the two structures exhibit the characteristic legume lectin tertiary fold. The quaternary structure resembles that of the Phaseolus vulgaris lectin, the soybean agglutinin, and the Dolichos biflorus lectin, but displays some unique features leading to the extreme stability of this lectin.
Subject(s)
Acacia/chemistry , Acetylglucosamine/metabolism , Lectins/chemistry , Lectins/metabolism , Acetylglucosamine/chemistry , Binding Sites , Crystallography, X-Ray , Hydrogen Bonding , Models, Molecular , Plant Lectins , Protein Binding , Protein Conformation , Static Electricity , Water/chemistry , Water/metabolismABSTRACT
The vitamin D binding protein binds globular actin with high affinity and is involved in the clearance of actin from the blood circulation. A complex of the human vitamin D binding protein and rabbit muscle actin was subjected to purification steps. The pure complex was crystallized using the hanging-drop vapour-diffusion procedure. The best obtained crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 74.44, b = 74.90, c = 88.02 A, beta = 110.19 degrees. A complete data set to 2.4 A was collected from a single crystal using synchrotron radiation at DESY, Hamburg, Germany.
Subject(s)
Actins/chemistry , Muscles/chemistry , Vitamin D-Binding Protein/chemistry , Actins/isolation & purification , Animals , Crystallization , Crystallography, X-Ray , Electrophoresis, Polyacrylamide Gel , Humans , Protein Conformation , Rabbits , Vitamin D-Binding Protein/isolation & purificationABSTRACT
MornigaM, a lectin from Morus nigra, belongs to the mannose-binding subgroup of the family of jacalin-related plant lectins. It was crystallized in the P6(5) space group, with unit-cell parameters a = b = 110.74, c = 159.28 A. The partially merohedrally twinned crystals could be detwinned and a subsequent molecular-replacement solution could be found using the coordinates of jacalin. Preliminary analysis clearly shows the tetrameric assembly of this protein. Furthermore, data from MornigaM crystals soaked in a mannose solution were collected.
Subject(s)
Lectins/chemistry , Magnoliopsida/chemistry , Mannose/metabolism , Crystallization , Interferon Inducers/chemistry , Lectins/metabolism , Plant Lectins , Protein Structure, Quaternary , Structure-Activity Relationship , Substrate Specificity , X-Ray DiffractionABSTRACT
The A(4) isoform of the bark lectin RPbAI from Robinia pseudoacacia has been crystallized in two different crystal forms. Crystal form I grows in the P2(1) space group with two tetramers in the asymmetric unit, whereas crystal form II grows in the I222 space group with a monomer in the asymmetric unit. Data sets were collected for both crystal forms to resolution limits of 2.55 and 1.81 A, respectively, which will allow successful structure determinations.
Subject(s)
Fabaceae/chemistry , Lectins/chemistry , Plants, Medicinal , Crystallization , Lectins/isolation & purification , Plant Lectins , Polymers/chemistry , Protein Conformation , X-Ray DiffractionABSTRACT
Vitamin D-binding protein (DBP), a multifunctional, highly polymorphic glycoprotein responsible for the transport of vitamin D and for sequestering extracellular actin, was isolated from human serum and crystallized using vapour diffusion methods. The crystals were grown from 7.5% v/v polyethylene glycol 400 and 0.1 M acetate buffer at pH 4.6. These crystals show diffraction patterns consistent with the tetragonal space groups P4(1) and P4(3) with unit cell dimensions a = b = 135.5(4) A and c = 75.9(4) A. They diffract to 2.3 A. Using polyacrylamide gel electrophoresis it was shown that according to their electrophoretic mobility the O-glycosylated isoforms, with a terminal sialic acid residue, are absent in the crystals.
