pre-mRNA的剪切.ppt

关于pre-mRNA的剪切Jovenhaha1.Yigong Shi,Ph.D 施一公 教授University ProfessorSchool of Life SciencesTsinghua UniversityTel(lab):86(10)62797560Tel(asst.):86(10)627810532.The Team3.The TeamThe SHI laboratory combines structural biology,biochemical and biophysical approaches to elucidate the molecular and chemical basis of fundamental cellular events.4.Gene expression in all eukaryotes consists of three essential steps:transcription of DNA into pre-mRNA,splicing of pre-mRNA into mature mRNA,and translation of mature mRNA into protein.These steps constitute the core principle of Central Dogma in molecular biology.Each pre-mRNA contains a distinct number of the coding exons and the intervening non-coding introns,each with a varying length and unique sequence.Aberrant splicing contributes to numerous debilitating diseases.Research：5.Splicing of pre-mRNA is executed by the spliceosomes,which consist of five small nuclear ribonucleoprotein particles(snRNPs)and a large number of associated enzymes and cofactors.The spliceosome exhibits exceptional compositional dynamics and conformational flexibility,consistent with its function of splicing introns with diverse sequences.They have determined the three-dimensional structure of a Schizosaccharomyces pombe spliceosome at 3.6-resolution and elucidated the structural basis of pre-mRNA splicing.Science,349,118291(2015);Science,349,11918(2015)Research：6.The resolved yeast spliceosome contains U2 snRNP,U5 snRNP,nineteen complex(NTC),NTC related complex(NTR),U6 snRNA,and an RNA intron lariat.The atomic model includes 10,574 amino acids from 37 proteins and 4 RNA molecules,with a combined molecular mass of approximately 1.3 mega-Daltons.Research：7.In the structure,U5 snRNP acts as a central scaffold onto which U6 and U2 snRNAs are intertwined to form a catalytic center next to Loop I of U5 snRNA.The catalytic magnesium ions are coordinated by conserved nucleotides in U6 snRNA.The intron lariat is held in place through base pairing interactions with both U2 and U6 snRNAs.Thus,the spliceosome is in essence a protein-directed ribozyme,with the protein components essential for the delivery of critical RNA molecules into close proximity of one another at the right time for the splicing reaction.Research：8.2016Ruixue Wan,Chuangye Yan,Rui Bai,Lin Wang,Min Huang,Catherine C.L.Wong,Yigong Shi.(2016)The 3.8 structure of the U4/U6.U5 tri-snRNP:Insights into spliceosome assembly and catalysis.Science.(6272):466-75.Epub 2016 Jan 7.2015Mengying Zhou1,Yini Li1,Qi Hu1,Xiao-chen Bai,Weiyun Huang,Chuangye Yan,Sjors H.W.Scheres and Yigong Shi.(2015)Atomic structure of the apoptosome:mechanism of cytochrome c-and dATP-mediated activation of Apaf-1.Genes&Dev.2015.29:2349-2361.Xiao-chen Bai,Eeson Rajendra,Guanghui Yang,Yigong Shi,Sjors HW Scheres(2015)Sampling the conformational space of the catalytic subunit of human?-secretase.eLife.10.7554/eLife.11182Jing Hang,Ruixue Wan,Chuangye Yan,Yigong Shi.(2015)Structural basis of pre-mRNA splicing.Science.349(6253):1191-1198.Chuangye Yan,Jing Hang,Ruixue Wan,Min Huang,Catherine C.L.Wong,Yigong Shi.(2015)Structure of a yeast spliceosome at 3.6-angstrom resolution.Science.349(6253):1182-1191.Xiao-chen Bai,Chuangye Yan,Guanghui Yang,Peilong Lu,Dan Ma,Linfeng Sun,Rui Zhou,Sjors H.W.Scheres,Yigong Shi.(2015)An atomic structure of human-secretase.Nature.525(7568):212-217.Linfeng Sun,Lingyun Zhao,Guanghui Yang,Chuangye Yan,Rui Zhou,Xiaoyuan Zhou,Tian Xie,Yanyu Zhao,Shenjie Wu,Xueming Li,Yigong Shi.(2015)Structural basis of human-secretase assembly.Proc Natl Acad Sci U S A.112(19):6003-6008.Shangyu Dang,Shenjie Wu,Jiawei Wang,Hongbo Li,Min Huang,Wei He,Yue-Ming Li,Catherine C.L.Wong,Yigong Shi.(2015)Cleavage of amyloid precursor protein by an archaeal presenilin homologue PSH.Proc Natl Acad Sci U S A.112(11):3344-3349.Yuxuan Pang,Xiao-chen Bai,Qi Hao,Chuangye Yan,Zheqin Chen,Jia-Wei Wang,Sjors H.W.Scheres,Yigong Shi.(2015)Structure of the apoptosome:mechanistic insights into activation of an initiator caspase from Drosophila.Genes Dev.29(3):277-287Zhen Yan,Xiao-chen Bai,Chuangye Yan,Jianping Wu,Zhangqiang Li,Tian Xie,Wei Peng,Chang-cheng Yin,Xueming Li,Sjors H.W.Scheres,Yigong Shi,Nieng Yan.(2015)Structure of the rabbit ryanodine receptor RyR1 at near-atomic resolution.Nature.517(7532):50-55.Publications：9.Prof.Dr.Reinhard LhrmannProf.Dr.Reinhard LhrmannMax Planck Institute for Biophysical Chemistry,Gttingen（马克斯普朗克生物物理化学研究所，哥廷根）Phone:[phone]Fax:[phone]Email:reinhard.luehrmannmpi-bpc.mpg.de10.Reinhard Lhrmann is director of the Department of Cellular Biochemistry at the Max Planck Institute for Biophysical Chemistry in Gttingen.After obtaining his PhD from the University of Mnster and carrying out post-doctoral work at the Max Planck Institute of Molecular Genetics in Berlin,he headed an independent Max Planck research group at the Otto Warburg Laboratory in Berlin.From 1988 to 2000 he was Professor of Molecular Biology at the University of Marburg.11.Reinhard Lhrmann has made seminal contributions to our understanding of the biochemistry and nucleo-cytoplasmic transport of U snRNPs,and the structure and function of the spliceosome.Reinhard Lhrmann has served on editorial boards,including those of RNA and the EMBO Journal,as director and president of the RNA Society,and he is an elected member of EMBO and the German Academy Leopoldina.12.Major Research Interests：Most metazoan pre-mRNAs contain multiple introns and exons.In order to generate mature mRNA,the introns must be excised from the pre-mRNA,a process termed pre-mRNA splicing.In many cases,alternative splicing generates different mRNAs from a single pre-mRNA by the regulated removal of different sections of the RNA,a process which greatly expands the complexity of the repertoire of proteins that can be expressed from relatively small genomes.Splicing is catalysed by a large macromolecular machine,termed the spliceosome which consists of the small nuclear RNAs(U1,U2,U4,U5 and U6)and more than 150 proteins,50 of which are associated with the snRNAs to form snRNPs.13.In his laboratory,intense efforts are focussed on understanding how the spliceosome recognizes and binds the intron ends and discriminates them from exons.This is an especially confounding problem in metazoans because,in contrast to lower eucaryotes such as yeast,pre-mRNA introns are often extremely long(104-105 nucleotides),while exons are generally small(less than 300 nucleotides).Another major goal of their research is the elucidation of the mechanisms by which the spliceosome assembles into a catalytically active machine and catalyses intron excision.14.Finally,they are investigating the 3D structure of purified spliceosomes or major building blocks thereof using electron microscopic approaches and X ray crystallography.Their studies on the regulatory mechanisms of constitutive and alternative pre-mRNA splicing involve mainly mammalian systems.As the basic mechanisms of splicing catalysis appear to be evolutionarily highly conserved,they are also taking advantage of molecular genetic approaches in bakers yeast to elucidate the structure and function of the catalytic core domain of the spliceosome.15.The production of proteins in the cells of higher organisms is a complex process involving many steps.First,the genetic information for a protein is rewritten from DNA into a working copy,the precursor messenger RNA(pre mRNA).However,pre-mRNAs contain regions that do not contain information used for the production of proteins(the so-called“introns”).These regions must be precisely cut out and the remaining regions,which contain usable information(the“exons”),linked together.This maturation process is termed pre-mRNA splicing”.Only mature mRNAs,that are transported from the cell nucleus into the cytoplasm,can be used by the ribosome as a template for the production of proteins.16.The presence of exons and introns is a great advantage for an organism,as different combinations of exons from a given pre-mRNA species can be chosen to be included in the mature mRNA product.In this way,mRNAs corresponding to many different proteins can be made from a single gene.This so-called alternative splicing represents an additional level at which gene expression can be regulated.This explains why humans manage with only just over 20,000 protein-encoding genes in their genomes.Understanding splicing at the molecular level is of great medical relevance,as aberrant pre-mRNA splicing is the basis or a severity modifier of a plethora of human diseases.17.The pre-mRNA splicing reaction takes place in two steps.Both involve phosphoester-transfer reactions,and both are carried out by a macromolecular machine,the spliceosome.Spliceosomes consist of well over 100 proteins and five small RNA molecules(the snRNAs U1,U2,U4,U5 and U6)and thus consist largely of protein.Many of the spliceosomes components are organised into smaller,stable sub-complexes.For example,about 50 of the spliceosomal proteins are stably bound to the snRNAs,forming RNAprotein particles(termed small nuclear ribonucleoproteins or snRNPs)which include the U1 and U2 snRNPs and the U4/U6.U5 tri-snRNP.18.The Max Planck Society is Germanys most successful research organization.Since its establishment in 1948,no fewer than 18 Nobel laureates have emerged from the ranks of its scientists,putting it on a par with the best and most prestigious research institutions worldwide.The more than 15,000 publications each year in internationally renowned scientific journals are proof of the outstanding research work conducted at Max Planck Institutes and many of those articles are among the most-cited publications in the relevant field.19.Directors|Research FocusPatrick Cramer|Molecular BiologyGregor Eichele|Genes and BehaviorDirk Grlich|Cellular LogisticsChristian Griesinger|NMR based Structural BiologyHelmut Grubmller|Theoretical and Computational BiophysicsStefan W.Hell|NanoBiophotonicsHerbert Jckle|Molecular Developmental BiologyReinhard Jahn|NeurobiologyReinhard Lhrmann|Cellular BiochemistryMarina V.Rodnina|Physical BiochemistryAlec Wodtke|Dynamics at surfacesPeter Gruss,em.|Molecular Cell BiologyErwin Neher,em.|Membrane Biophysics20.Thanks for your attention!21.