Fellutamide B is a potent inhibitor of the Mycobacterium tuberculosis proteasome.
Via high-throughput screening of a natural compound library, we have identified a lipopeptide aldehyde, fellutamide B (1), as the most potent inhibitor of the Mycobacterium tuberculosis (Mtb) proteasome tested to date. Kinetic studies reveal that 1 inhibits both Mtb and human proteasomes in a time-dependent manner under steady-state condition. Remarkably, 1 inhibits the Mtb proteasome in a single-step binding mechanism with K(i)=6.8 nM, whereas it inhibits the human proteasome beta5 active site following a two-step mechanism with K(i)=11.5 nM and K(i)(*)=0.93 nM. Co-crystallization of 1 bound to the Mtb proteasome revealed a structural basis for the tight binding of 1 to the active sites of the Mtb proteasome. The hemiacetal group of 1 in the Mtb proteasome takes the (R)-configuration, whereas in the yeast proteasome it takes the (S)-configuration, indicating that the pre-chiral CHO group of 1 binds to the active site Thr1 in a different orientation. Re-examination of the structure of the yeast proteasome in complex with 1 showed significant conformational changes at the substrate-binding cleft along the active site. These structural differences are consistent with the different kinetic mechanisms of 1 against Mtb and human proteasomes.
Lin
Gang
G
Department of Microbiology and Immunology, Weill Medical College of Cornell University, 1300 York Ave., New York, NY 10065, United States. gal2005@med.cornell.edu
Li
Dongyang
D
Chidawanyika
Tamutenda
T
Nathan
Carl
C
Li
Huilin
H
D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D020134:Catalytic Domain; D004353:Drug Evaluation, Preclinical; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D055666:Lipopeptides / Q000494:pharmacology*; D008958:Models, Molecular; D050505:Mutant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D011480:Protease Inhibitors / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000235:genetics; D061988:Proteasome Inhibitors; D011487:Protein Conformation; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D013045:Species Specificity
D001426:Bacterial Proteins; D055666:Lipopeptides; D050505:Mutant Proteins; D011480:Protease Inhibitors; D061988:Proteasome Inhibitors; D029701:Saccharomyces cerevisiae Proteins; C513652:fellutamide B; D046988:Proteasome Endopeptidase Complex