6LOQ image
Entry Detail
PDB ID:
6LOQ
Keywords:
PLANT PROTEIN
Title:
crystal structure of alpha-momorcharin in complex with cAMP
Biological Source:
Source Organism:
Momordica charantia
PDB Version:
Deposition Date:
2020-01-07
Release Date:
2020-11-18
Method Details:
Experimental Method:
X-RAY DIFFRACTION
Resolution:
1.33 Å
R-Value Free:
0.25
R-Value Work:
0.21
Space Group:
H 3
6LOQ validation report
Macromolecular Entities
Protein Blast
Polymer Type:polypeptide(L)
Description:Ribosome-inactivating protein momordin I
Chain IDs:A
Chain Length:286
Number of Molecules:1
Biological Source:Momordica charantia
UniProt ID:P16094 Pfam ID:PF00161 EC:3.2.2.22
Ligand Molecules
CMP
Primary Citation
Atomic-resolution structures of type I ribosome inactivating protein alpha-momorcharin with different substrate analogs.
Int.J.Biol.Macromol. 164 265 276 (2020)
PMID: 32653369 DOI: 10.1016/j.ijbiomac.2020.07.063

Abstact

Alpha-momorcharin (Alpha-MMC) from the seed of bitter melon is a type I ribosome inactivating protein (RIP) that removes a specific adenine from 28S rRNA and inhibits protein biosynthesis. Here, we report seven crystal complex structures of alpha-MMC with different substrate analogs (adenine, AMP, cAMP, dAMP, ADP, GMP, and xanthosine) at 1.08 Å to 1.52 Å resolution. These structures reveal that not only adenine, but also guanine and their analogs can effectively bind to alpha-MMC. The side chain of Tyr93 adopts two conformations, serving as a switch to open and close the substrate binding pocket of alpha-MMC. Although adenine, AMP, GMP, and guanine are located in a similar active site in different RIPs, residues involved in the interaction between RIPs and substrate analogs are slightly different. Complex structures of alpha-MMC with different substrate analogs solved in this study provide useful information on its enzymatic mechanisms and may enable the development of new inhibitors to treat the poisoning of alpha-MMC.

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Primary Citation of related structures
6LOQ