Geneeditingisoneofthelatestbreakthroughsinbiology.Thewell-knownCRISPR-Casgeneediting systemconfersimmunityagainstforeignDNAtoprokaryotes(organismslackingacellnucleus).Since thediscoveryofCRISPRgeneeditingtechnology,scientistshaverevealedhowCRISPR-casproteins evolvedfromtheirprecursors.Thisknowledgewillhelpthemdevelopothersmallnewgenomeediting toolsforgenetherapy.
At the University of Tokyo, Professor Osamu Nureki’s team worked to identify the structure and functionofproteinsinvolvedingenomeediting.Inarecentstudybytheteam,theydiscoveredthe3D structure ofprotein TnpB, apossibleprecursor to the CRISPR-Cas12 enzyme.Their findingswere publishedinNature.
PreviousresearchhasshownthattheTnpBproteinmayactlikeapairofmolecular scissors,cutting DNAwiththehelp ofaspecialtypeofnon-codingRNAcalledomegaRNA.ButhowRNA-guided DNAcleavageworks,anditsevolutionaryrelationshiptotheCas12enzyme,wasunclear,prompting research fromNureki’slab.The first andmost critical step in their understandingwastoreveal the protein’sstructure.
Todeterminethethree-dimensionalstructureofTnpB,theresearchersextractedtheTnpBproteinfrom a bacterium called Deinococcus radiodurans and used cryo-electron microscopy. In cryo-electron microscopy,aproteinsampleiscooledto-196°Cusingliquidnitrogenandilluminatedwithanelectron beam,revealingtheprotein’s3Dstructure.
TheteamfoundthattheomegaRNAinTnpBhasauniquepseudoknotshape,similartotheguideRNA fortheCas12enzyme.ThestudyalsorevealedhowTnpBrecognizesomegaRNAsandcleavestarget DNA. When they compared the structure of this protein to the Cas12 enzyme, they learned two possiblewaysthatTnpBmighthaveevolvedintoaCRISPR-Cas12enzyme. “OurfindingsprovidemechanisticinsightsintoTnpBfunctionandadvanceourunderstandingofthe evolutionofTnpBproteinstoCRISPR-Cas12effectors,”saidRyoyaNakagawa,oneofthefirstauthors of the research paper. He added that, “In the future, we will explore the potential application of tnpb-basedgeneeditingtechnology.”
About the author Collectedby CreativeBiostructure.CreativeBiostructurehasbeenworkinginthefieldofstructural biology,membraneprotein technologies,and structure-based drug discovery.Wehave expertise and experience in protein 3D structureprediction,protein modeling, and data analysis.Related services include: Rheo-NMR service, co-crystallization, membrane protein structure determination by solid-state NMR, stable isotope labeling for nucleic acids, crystallization chaperone strategies, and immunoelectronmicroscopyservice.
