Highly dispersed CeO_(2-x)nanoparticles with rich oxygen vacancies enhance photocatalytic performance of g-C_(3)N_(4)toward methyl orange degradation under visible light irradiation

CeO_(2)/g-C_(3)N_(4)photocatalysts have attracted tremendous attention in the photocatalytic degradation of organic pollutants.The design and construction of highly active CeO_(2)/g-C_(3)N_(4)photocatalysts without harsh conditions are still challenging.Herein,highly dispersed CeO_(2-x)nanoparticles with rich oxygen vacancies were successfully precipitated on the surface of g-C_(3)N_(4)under mild conditions.The fabricated CeO_(2-x)/g-C_(3)N_(4)exhibits remarkable activity and stability for photocatalytic degradation of MO pollutant.The optimal rate constant of MO degradation over CeO_(2-x)/g-C_(3)N_(4)is about 0.031 min^(-1),which is three times higher than that of g-C_(3)N_(4).A negligible activity decrease is observed after three cycling runs.The enhanced catalytic performance can be ascribed to the excellent dispersion of CeO_(2-x)with rich oxygen vacancies that benefit O_(2)adsorption and visible light absorption.In addition,the proper band alignment between CeO_(2-x)and gC_(3)N_(4)is conducive to the highly efficient separation of photogenerated electron-hole pairs.

Structural and functional characterization of multiple myeloma associated cytoplasmic poly(A) polymerase FAM46C

Background:Multiple myeloma(MM)is a hematologic malignancy characterized by the accumulation of aberrant plasma cells within the bone marrow.The high frequent mutation of family with sequence similarity 46,member C(FAM46C)is closely related with the occurrence and progression of MM.Recently,FAM46C has been identified as a non-canonical poly(A)polymerase(PAP)that functions as a tumor suppressor in MM.This study aimed to elucidate the structural features of this novel non-canonical PAP and how MM-related mutations affect the structural and biochemical properties of FAM46C,eventually advancing our understandings towards FAM46C mutation-related MM occurrence.Methods:We purified and crystallized a mammalian FAM46C construct,and solved its structure.Next,we characterized the property of FAM46C as a PAP through a combination of structural analysis,site-directed mutagenesis and biochemical assays,and by comparison with its homolog FAM46B.Finally,we structurally analyzed MM-related FAM46C mutations and tested the enzymatic activity of corresponding mutants.Results:We determined the crystal structure of a mammalian FAM46C protein at 2.35 A,and confirmed that FAM46C preferentially consumed adenosine triphosphate(ATP)and extended A-rich RNA substrates.FAM46C showed a weaker PAP activity than its homolog FAM46B,and this difference was largely dependent on the residue variance at particular sites.Of them,residues at positions 77,290,and 298 of mouse FAM46C weremost important for the divergence in enzymatic activity.Among the MM-associated FAM46C mutants,those residing at the catalytic site(D90G and D90H)or putative RNA-binding site(I155L,S156F,D182Y,F184L,Y247V,andM270V)showed abolished or compromised PAP activity of FAM46C,while N72A and S248A did not severely affect the PAP activity.FAM46C mutants D90G,D90H,I155L,S156F,F184L,Y247V,and M270V had significantly lower inhibitory effect on apoptosis of RPMI-8226 cells as compared to wild-type FAM46C.Conclusions:FAM46C is a prokaryotic-like PAP with preference forA-richRNA substrates,and showed distinct enzymatic efficiency with its homolog FAM46B.The MM-related missense mutations of FAM46C lead to various structural and biochemical outcomes to the protein.