Supporting information for this article is given via a link at the end of the document.

Collagen prolyl 4-hydroxylase (C-P4H) catalyzes the proline hydroxylation of procollagen, an essential modification in the maturation of collagens. C-P4H consists of two catalytic α subunits and two protein disulfide isomerase β subunits. The assembly of these subunits is unknown. The α subunit contains an N domain (1-143), a peptide-substrate-binding-domain (PSB, 144-244) and a catalytic domain (245-517). Here, we report the dimeric structure of the N-terminal region (1-244) of the α subunit. It is shown that the N domain has an important role in the assembly of the C-P4H tetramer, by forming an extended four-helix bundle that includes an antiparallel coiled-coil dimerization motif between the two α subunits. Complexes of this construct with a C-P4H inhibitor and substrate show the mode of peptide-binding to the PSB domain. Both peptides adopt a poly-(L)-proline-type-II helix conformation and bind in a curved, asymmetric groove lined by conserved tyrosines and an Arg-Asp salt bridge.

EYA proteins (EYA1-4) are critical developmental transcriptional cofactors that contain an EYA domain (ED) harboring Tyr phosphatase activity. EYA proteins are largely downregulated after embryogenesis but are reexpressed in cancers, and their Tyr phosphatase activity plays an important role in the DNA damage response and tumor progression. We previously identified a class of small-molecule allosteric inhibitors that specifically inhibit the Tyr phosphatase activity of EYA2. Herein, we determined the crystal structure of the EYA2 ED in complex with NCGC00249987 (a representative compound in this class), revealing that it binds to an induced pocket distant from the active site. NCGC00249987 binding leads to a conformational change of the active site that is unfavorable for Mg 2þ binding, thereby inhibiting EYA2's Tyr phosphatase activity. We demonstrate, using genetic muta-tions, that migration, invadopodia formation, and invasion of lung adenocarcinoma cells are dependent on EYA2 Tyr phosphatase activity, whereas growth and survival are not. Further, we demonstrate that NCGC00249987 specifically targets migration, invadopodia formation, and invasion of lung cancer cells, but that it does not inhibit cell growth or survival. The compound has no effect on lung cancer cells carrying an EYA2 F290Y mutant that abolishes compound binding, indicating that NCGC00249987 is on target in lung cancer cells. These data suggest that the NCGC00249987 allosteric inhibitor can be used as a chemical probe to study the function of the EYA2 Tyr phosphatase activity in cells and may have the potential to be developed into an antimetastatic agent for cancers reliant on EYA2's Tyr phosphatase activity.

Collagen prolyl 4-hydroxylase (C-P4H), an αβ heterotetramer, is a crucial enzyme for collagen synthesis. The α-subunit consists of an N-terminal dimerization domain, a central peptide substrate-binding (PSB) domain, and a C-terminal catalytic (CAT) domain. The β-subunit [also known as protein disulfide isomerase (PDI)] acts as a chaperone, stabilizing the functional conformation of C-P4H. C-P4H has been studied for decades, but its structure has remained elusive. Here, we present a three-dimensional small-angle X-ray scattering model of the entire human C-P4H-I heterotetramer. C-P4H is an elongated, bilobal, symmetric molecule with a length of 290 Å. The dimerization domains from the two α-subunits form a protein-protein dimer interface, assembled around the central antiparallel coiled-coil interface of their N-terminal α-helices. This region forms a thin waist in the bilobal tetramer. The two PSB/CAT units, each complexed with a PDI/β-subunit, form two bulky lobes pointing outward from this waist region, such that the PDI/β-subunits locate at the far ends of the βααβ complex. The PDI/β-subunit interacts extensively with the CAT domain. The asymmetric shape of two truncated C-P4H-I variants, also characterized in the present study, agrees with this assembly. Furthermore, data from these truncated variants show that dimerization between the α-subunits has an important role in achieving the correct PSB-CAT assembly competent for catalytic activity. Kinetic assays with various proline-rich peptide substrates and inhibitors suggest that, in the competent assembly, the PSB domain binds to the procollagen substrate downstream from the CAT domain.

Supporting information for this article is given via a link at the end of the document.

The peptide-substrate-binding (PSB) domain of collagen prolyl 4-hydroxylase (C-P4H, an α β tetramer) binds proline-rich procollagen peptides. This helical domain (the middle domain of the α subunit) has an important role concerning the substrate binding properties of C-P4H, although it is not known how the PSB domain influences the hydroxylation properties of the catalytic domain (the C-terminal domain of the α subunit). The crystal structures of the PSB domain of the human C-P4H isoform II (PSB-II) complexed with and without various short proline-rich peptides are described. The comparison with the previously determined PSB-I peptide complex structures shows that the C-P4H-I substrate peptide (PPG) , has at most very weak affinity for PSB-II, although it binds with high affinity to PSB-I. The replacement of the middle PPG triplet of (PPG) to the nonhydroxylatable PAG, PRG, or PEG triplet, increases greatly the affinity of PSB-II for these peptides, leading to a deeper mode of binding, as compared to the previously determined PSB-I peptide complexes. In these PSB-II complexes, the two peptidyl prolines of its central P(A/R/E)GP region bind in the Pro5 and Pro8 binding pockets of the PSB peptide-binding groove, and direct hydrogen bonds are formed between the peptide and the side chains of the highly conserved residues Tyr158, Arg223, and Asn227, replacing water mediated interactions in the corresponding PSB-I complex. These results suggest that PxGP (where x is not a proline) is the common motif of proline-rich peptide sequences that bind with high affinity to PSB-II.

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Targeted covalent inhibitors have re-emerged as validated drugs to overcome acquired resistance in cancer treatment. Herein, by using a carbonyl boronic acid warhead, we report the structure-based design of BCR-ABL inhibitors via reversible covalent targeting of the catalytic lysine with improved single-digit nanomolar potency against both wild-type and mutant ABL kinases, especially ABL^T315I bearing the gatekeeper residue mutation. We show that, by using techniques including mass spectrometry, time-dependent biochemical assays and X-ray crystallography, the evolutionarily conserved lysine can be targeted selectively. Furthermore, we show that the selectivity depends largely on molecular recognition of the non-covalent pharmacophore in this class of inhibitors, probably due to the moderate reactivity of the warhead. We report the first co-crystal structures of covalent inhibitor-ABL kinase domain complexes, providing insights into the interaction of this warhead with the catalytic lysine. We also employed label-free mass spectrometry to evaluate potential off-targets of our compounds at proteome-wide level in different cancer cell lines.