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Publication Abstract from PubMed

The ClpP protease complex and its regulatory ATPases, ClpC1 and ClpX, in Mycobacterium tuberculosis (Mtb) are essential and therefore promising drug targets. The Mtb ClpP protease consists of two heptameric rings, one composed of ClpP1 and one of ClpP2 subunits. Formation of the enzymatically active ClpP1P2 complex requires binding of N-blocked dipeptide activators. We have found a new potent activator (benzoyl-leucine-leucine (Bz-LL)) that binds more tightly and stimulates its peptidase activity 3-4-fold more than previous activators. Bz-LL-activated ClpP1P2 stimulated specifically the ATPase activity of Mtb ClpC1 or ClpX, and the resulting holoenzyme complexes exhibit 2-3-fold enhanced ATPase activity, peptide cleavage and ATP-dependent protein degradation. The crystal structure of ClpP1P2 with bound Bz-LL was determined at a resolution of 3.07 A and with benzyloxy carbonyl (Z)-LL bound at 2.9 A. Bz-LL is present in all 14 active sites, whereas no Z-LL density was visible. Surprisingly, Bz-LL adopts opposite orientations in ClpP1 and ClpP2. In ClpP1, Bz-LL binds with the C-terminal leucine side chain in the S1 pocket. One carboxy-terminal oxygen is close to the catalytic serine, while the other contacts backbone amides in the oxyanion hole. In ClpP2, Bz-LL binds with the benzoyl group in the S1 pocket and the peptide hydrogen bonded between parallel beta-strands. The ClpP2 axial loops are extended forming an open axial channel as was previously observed with bound ADEP antibiotics. Thus occupancy of the active sites of ClpP allosterically alters sites on the surfaces that affect the association of ClpP1 and ClpP2 rings, interactions with regulatory ATPases, and entry of protein substrates.

Structure and Functional Properties of the active form of the proteolytic complex, ClpP1P2 from Mycobacterium tuberculosis.,Li M, Kandror O, Akopian T, Dharkar P, Wlodawer A, Maurizi MR, Goldberg AL J Biol Chem. 2016 Feb 8. pii: jbc.M115.700344. PMID:26858247^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.