Document Detail

Molecular basis of substrate promiscuity for the SAM-dependent O-methyltransferase NcsB1, involved in the biosynthesis of the enediyne antitumor antibiotic neocarzinostatin.
MedLine Citation:
PMID:  19702337     Owner:  NLM     Status:  MEDLINE    
The small molecule component of chromoprotein enediyne antitumor antibiotics is biosynthesized through a convergent route, incorporating amino acid, polyketide, and carbohydrate building blocks around a central enediyne hydrocarbon core. The naphthoic acid moiety of the enediyne neocarzinostatin plays key roles in the biological activity of the natural product by interacting with both the carrier protein and duplex DNA at the site of action. We have previously described the in vitro characterization of an S-adenosylmethionine-dependent O-methyltransferase (NcsB1) in the neocarzinostatin biosynthetic pathway [Luo, Y., Lin, S., Zhang, J., Cooke, H. A., Bruner, S. D., and Shen, B. (2008) J. Biol. Chem. 283, 14694-14702]. Here we provide a structural basis for NcsB1 activity, illustrating that the enzyme shares an overall architecture with a large family of S-adenosylmethionine-dependent proteins. In addition, NcsB1 represents the first enzyme to be structurally characterized in the biosynthetic pathway of neocarzinostatin. By cocrystallizing the enzyme with various combinations of the cofactor and substrate analogues, details of the active site structure have been established. Changes in subdomain orientation were observed via comparison of structures in the presence and absence of substrate, suggesting that reorientation of the enzyme is involved in binding of the substrate. In addition, residues important for substrate discrimination were predicted and probed through site-directed mutagenesis and in vitro biochemical characterization.
Heather A Cooke; Elizabeth L Guenther; Yinggang Luo; Ben Shen; Steven D Bruner
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemistry     Volume:  48     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2009-10-06     Completed Date:  2009-12-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9590-8     Citation Subset:  IM    
Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
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MeSH Terms
Antibiotics, Antineoplastic / biosynthesis*,  metabolism
Catalytic Domain / genetics
Crystallography, X-Ray
Enediynes / metabolism
Naphthols / chemistry
Protein Binding / genetics
Protein O-Methyltransferase / chemistry*,  genetics,  metabolism
S-Adenosylhomocysteine / chemistry
S-Adenosylmethionine / chemistry
Sequence Alignment
Sequence Homology, Amino Acid
Substrate Specificity
Zinostatin / biosynthesis*,  metabolism
Grant Support
Reg. No./Substance:
0/Antibiotics, Antineoplastic; 0/Enediynes; 0/Naphthols; 29908-03-0/S-Adenosylmethionine; 86-48-6/1-hydroxy-2-naphthoic acid; 9014-02-2/Zinostatin; 979-92-0/S-Adenosylhomocysteine; EC 2.1.1.-/Protein O-Methyltransferase

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