1RTC

THE STRUCTURE OF RECOMBINANT RICIN A CHAIN AT 2.3 ANGSTROMS

Summary for 1RTC

• Entry DOI: 10.2210/pdb1rtc/pdb
• Descriptor: RICIN (2 entities in total)
• Functional Keywords: glycosidase
• Biological source: Ricinus communis (castor bean)
• Total number of polymer chains: 1
• Total formula weight: 30067.95

Authors

Mlsna, D.,Monzingo, A.F.,Katzin, B.J.,Ernst, S.,Robertus, J.D. (deposition date: 1992-10-29, release date: 1993-10-31, Last modification date: 2024-02-14)

Primary citation

Mlsna, D.,Monzingo, A.F.,Katzin, B.J.,Ernst, S.,Robertus, J.D.
Structure of recombinant ricin A chain at 2.3 A.
Protein Sci., 2:429-435, 1993

PubMed Abstract: The plant cytotoxin ricin is a heterodimer with a cell surface binding (B) chain and an enzymatically active A chain (RTA) known to act as a specific N-glycosidase. RTA must be separated from B chain to attack rRNA. The X-ray structure of ricin has been solved recently; here we report the structure of the isolated A chain expressed from a clone in Escherichia coli. This structure of wild-type rRTA has and will continue to serve as the parent compound for difference Fouriers used to assess the structure of site-directed mutants designed to analyze the mechanism of this medically and commercially important toxin. The structure of the recombinant protein, rRTA, is virtually identical to that seen previously for A chain in the heterodimeric toxin. Some minor conformational changes due to interactions with B chain and to crystal packing differences are described. Perhaps the most significant difference is the presence in rRTA of an additional active site water. This molecule is positioned to act as the ultimate nucleophile in the depurination reaction mechanism proposed by Monzingo and Robertus (1992, J. Mol. Biol. 227, 1136-1145).

PubMed: 8453380

Experimental method

X-RAY DIFFRACTION (2.3 Å)