Salinosporamide A is a potent anticancer agent that entered phase 1 human clinical trials in May 2006 for the treatment of multiple myeloma only three years after its discovery from the obligate marine bacterium Salinispora tropica. This novel marine natural product possesses a densely functionalized y-lactam-p-lactone pharmacophore that is responsible for its irreversible binding to the 20S proteasome, a new drug target validated in cancer biology. Despite its clinical promise and its novel chemical structure, there are no reports on how this fermented drug is naturally created. The elucidation of the biosynthetic pathway to the salinosporamides will provide a number of opportunities to impact how salinosporamide A is commercially produced in the long-term and to afford ready access to new fermentation-based chemical variants for SAR studies through rational metabolic engineering. In addition, its unique chemical structure provides a number of rare opportunities to discover new biosynthetic processes that may have applied value as biocatalysts. Building upon a solid preliminary data foundation in which we have sequenced the 5.2 Mbp genome of S. tropica and identified the salinosporamide biosynthetic gene cluster through genome mining, mutagenesis, and protein expression, we propose in this new grant application to 1) elucidate the biosynthesis of the two novel biosynthetic building blocks chloroethylmalonyl-CoA and p-hydroxycyclohexenylalanine, 2) characterize the salinosporamide synthetase, an unprecedented hybrid polyketide synthase-peptide synthetase for Y-lactam-p-lactoneassembly, 3) genetically engineer and biologically evaluate new salinosporamide analogs, and 4) characterize the salinosporamide resistant 20S proteasome p-unit as a model for proteasome resistance for the future development of second-generationdrugs.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA127622-02
Application #
7359650
Study Section
Special Emphasis Panel (ZRG1-BCMB-B (03))
Program Officer
Fu, Yali
Project Start
2007-04-01
Project End
2012-01-31
Budget Start
2008-02-01
Budget End
2009-01-31
Support Year
2
Fiscal Year
2008
Total Cost
$280,761
Indirect Cost
Name
University of California San Diego
Department
Type
Schools of Pharmacy
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
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