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(FA...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.展开更多
We investigate the dynamics of a system coupled to an environment by averaged semiquantum method. The theory origins from the time-dependent variationalprinciple (TDVP) formulation and contains nondiagonal matrix elem...We investigate the dynamics of a system coupled to an environment by averaged semiquantum method. The theory origins from the time-dependent variationalprinciple (TDVP) formulation and contains nondiagonal matrix elements, thus it canbe applied to study dissipation, measurement and decoherence problems in the model.In the calculation, the influence of the environment governed by differential dynamical equation is incorporated using a mean field. We have performed averaged semiquantum method for a spin-boson model, which reproduces the results from stochasticSchrodinger equation method and Hierarchical approach quite accurately. Moreover,we validate our results with noninteracting-blip approximation (NIBA) and generalized Smoluchowski equation (GSE). The problem dynamics in nonequilibrium environments has also been studied by our method. When applied to the harmonic oscillator model coupled to a heat bath with different coupling strengths and dimensionalities of the bath, we find that the loss of coherence predicted by semiquantum methodis identical to the result of master equation with different initial state (Gaussian wavepacket and superposed wave packets).展开更多
基金National Key R&D Program of China,Grant/Award Number:2018YFA0508300National Natural Science Foundation of China,Grant/Award Numbers:81772977,31722016,31470729+1 种基金Natural Science Foundation of Guangdong Province,Grant/Award Numbers:2019TX05Y598,2014TQ01R584,2014A030312015Innovative Team Program of Guangzhou Regenerative Medicine and Health Guangdong Laboratory,Grant/Award Number:2018GZR110103002。
文摘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.
基金This work is supported by the National Science Foundation(Grant Nos.1037504 and 10875087).
文摘We investigate the dynamics of a system coupled to an environment by averaged semiquantum method. The theory origins from the time-dependent variationalprinciple (TDVP) formulation and contains nondiagonal matrix elements, thus it canbe applied to study dissipation, measurement and decoherence problems in the model.In the calculation, the influence of the environment governed by differential dynamical equation is incorporated using a mean field. We have performed averaged semiquantum method for a spin-boson model, which reproduces the results from stochasticSchrodinger equation method and Hierarchical approach quite accurately. Moreover,we validate our results with noninteracting-blip approximation (NIBA) and generalized Smoluchowski equation (GSE). The problem dynamics in nonequilibrium environments has also been studied by our method. When applied to the harmonic oscillator model coupled to a heat bath with different coupling strengths and dimensionalities of the bath, we find that the loss of coherence predicted by semiquantum methodis identical to the result of master equation with different initial state (Gaussian wavepacket and superposed wave packets).
