6xp3
Structure of human PYCR1 complexed with cyclopentanecarboxylic acidStructure of human PYCR1 complexed with cyclopentanecarboxylic acid
Structural highlights
DiseaseP5CR1_HUMAN Defects in PYCR1 are the cause of cutis laxa autosomal recessive type 2B (ARCL2B) [MIM:612940. A multisystem disorder characterized by the appearance of premature aging, wrinkled and lax skin with reduced elasticity, joint laxity, craniofacial dysmorphic features, intrauterine growth retardation with some degree of postnatal growth deficiency, and developmental delay.[1] [2] Defects in PYCR1 are the cause of cutis laxa, autosomal recessive, type 3B (ARCL3B) [MIM:614438. ARCL3B is a disorder characterized by an aged appearance with distinctive facial features, sparse hair, ophthalmologic abnormalities, intrauterine growth retardation, and cutis laxa.[3] [4] FunctionP5CR1_HUMAN Housekeeping enzyme that catalyzes the last step in proline biosynthesis. Can utilize both NAD and NADP, but has higher affinity for NAD. Involved in the cellular response to oxidative stress.[5] [6] Publication Abstract from PubMedPyrroline-5-carboxylate reductase 1 (PYCR1) catalyzes the biosynthetic half-reaction of the proline cycle by reducing Delta(1)-pyrroline-5-carboxylate (P5C) to proline through the oxidation of NAD(P)H. Many cancers alter their proline metabolism by upregulating the proline cycle and proline biosynthesis, and knockdowns of PYCR1 lead to decreased cell proliferation. Thus, evidence is growing for PYCR1 as a potential cancer therapy target. Inhibitors of cancer targets are useful as chemical probes for studying cancer mechanisms and starting compounds for drug discovery; however, there is a notable lack of validated inhibitors for PYCR1. To fill this gap, we performed a small-scale focused screen of proline analogs using X-ray crystallography. Five inhibitors of human PYCR1 were discovered: L-tetrahydro-2-furoic acid, cyclopentanecarboxylate, L-thiazolidine-4-carboxylate, L-thiazolidine-2-carboxylate, and N-formyl L-proline (NFLP). The most potent inhibitor was NFLP, which had a competitive (with P5C) inhibition constant of 100 mM. The structure of PYCR1 complexed with NFLP shows that inhibitor binding is accompanied by conformational changes in the active site, including the translation of an a-helix by 1 A. These changes are unique to NFLP and enable additional hydrogen bonds with the enzyme. NFLP was also shown to phenocopy the PYCR1knockdown in MCF10A H-RASV12 breast cancer cells by inhibiting de novo proline biosynthesis and impairing spheroidal growth. In summary, we generated the first validated chemical probe of PYCR1 and demonstrated proof-of-concept for screening proline analogs to discover inhibitors of the proline cycle. In Crystallo Screening for Proline Analog Inhibitors of the Proline Cycle Enzyme PYCR1.,Christensen EM, Bogner AN, Vandekeere A, Tam GS, Patel SM, Becker DF, Fendt SM, Tanner JJ J Biol Chem. 2020 Oct 27. pii: RA120.016106. doi: 10.1074/jbc.RA120.016106. PMID:33109600[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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