PDBsum entry 4zlb

Hydrolase

PDB id: 4zlb

Contents

Protein chains

247 a.a.

261 a.a.

Ligands

NAG-NAG

NAG-FUC

NAG-BMA

BGC-GAL

NAG

XYP

Waters ×179

PDB id:

4zlb

Name:

Hydrolase

Title:

Structural studies on a non-toxic homologue of type ii rips from momordica charantia (bitter gourd) in complex with lactose

Structure:

Rrna n-glycosidase. Chain: a. Fragment: unp residues 24-270. Rrna n-glycosidase. Chain: b. Fragment: unp residues 287-547. Ec: 3.2.2.22

Source:

Momordica charantia. Bitter gourd. Organism_taxid: 3673. Organism_taxid: 3673

Resolution:

2.55Å R-factor: 0.248 R-free: 0.292

Authors:

T.Chandran,A.Sharma,M.Vijayan

Key ref:

T.Chandran et al. (2015). Structural studies on a non-toxic homologue of type II RIPs from bitter gourd: Molecular basis of non-toxicity, conformational selection and glycan structure. J Biosci, 40, 929-941. PubMed id: 26648038

Date:

01-May-15 Release date: 23-Mar-16

Protein chain

B7X8M2  (B7X8M2_MOMCH) -  Ribosome-inactivating protein from Momordica charantia

Seq: 547 a.a.

Struc: 247 a.a.

Protein chain

B7X8M2  (B7X8M2_MOMCH) -  Ribosome-inactivating protein from Momordica charantia

Seq: 547 a.a.

Struc: 261 a.a.

Enzyme reactions

• Enzyme class: Chains A, B: E.C.3.2.2.22 - rRNA N-glycosylase.
• Reaction: Endohydrolysis of the N-glycosidic bond at one specific adenosine on the 28S rRNA.

J Biosci 40:929-941 (2015)

PubMed id: 26648038

Structural studies on a non-toxic homologue of type II RIPs from bitter gourd: Molecular basis of non-toxicity, conformational selection and glycan structure.

T.Chandran, A.Sharma, M.Vijayan.

ABSTRACT

The structures of nine independent crystals of bitter gourd seed lectin (BGSL), a non-toxic homologue of type II RIPs, and its sugar complexes have been determined. The four-chain, two-fold symmetric, protein is made up of two identical two-chain modules, each consisting of a catalytic chain and a lectin chain, connected by a disulphide bridge. The lectin chain is made up of two domains. Each domain carries a carbohydrate binding site in type II RIPs of known structure. BGSL has a sugar binding site only on one domain, thus impairing its interaction at the cell surface. The adenine binding site in the catalytic chain is defective. Thus, defects in sugar binding as well as adenine binding appear to contribute to the non-toxicity of the lectin. The plasticity of the molecule is mainly caused by the presence of two possible well defined conformations of a surface loop in the lectin chain. One of them is chosen in the sugar complexes, in a case of conformational selection, as the chosen conformation facilitates an additional interaction with the sugar, involving an arginyl residue in the loop. The N-glycosylation of the lectin involves a plant-specific glycan while that in toxic type II RIPs of known structure involves a glycan which is animal as well as plant specific.