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8dkg
From Proteopedia
Structure of PYCR1 Thr171Met variant complexed with NADH
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 (PYCR) is a proline biosynthetic enzyme that catalyzes the NAD(P)H-dependent reduction of Delta(1)-pyrroline-5-carboxylate (P5C) to proline. Humans have three PYCR isoforms, with PYCR1 often upregulated in different types of cancers. Here, we studied the biochemical and structural properties of the Thr171Met variant of PYCR1, which is found in patients with malignant melanoma and lung adenocarcinoma. Although PYCR1 is strongly associated with cancer progression, characterization of a PYCR1 variant in cancer patients has not yet been reported. Thr171 is conserved in all three PYCR isozymes and is located near the P5C substrate binding site. We found that the amino acid replacement does not affect thermostability but has a profound effect on PYCR1 catalytic activity. The k (cat) of the PYCR1 variant T171M is 100- to 200-fold lower than wild-type PYCR1 when P5C is the variable substrate, and 10- to 25-fold lower when NAD(P)H is varied. A 1.84 A resolution X-ray crystal structure of T171M reveals that the Met side chain invades the P5C substrate binding site, suggesting that the catalytic defect is due to steric clash preventing P5C from achieving the optimal pose for hydride transfer from NAD(P)H. These results suggest that any impact on PYCR1 function associated with T171M in cancer does not derive from increased catalytic activity. Functional Impact of a Cancer-Related Variant in Human Delta(1)-Pyrroline-5-Carboxylate Reductase 1.,Daudu OI, Meeks KR, Zhang L, Seravalli J, Tanner JJ, Becker DF ACS Omega. 2023 Jan 10;8(3):3509-3519. doi: 10.1021/acsomega.2c07788. eCollection , 2023 Jan 24. PMID:36713721[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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