FnoCas12a bridge helix variant state 4b. Determined by electron microscopy at 3.21 Å resolution. Released 11 Feb 2026.
Explore 9MKX in 3D Show helices and sheets RCSB PDB PDBe
9MKX contains 68 α-helices and 35 β-strands across 1 chain. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.
| Element | Residues | Length | Sheet |
|---|---|---|---|
| β-strand | 15-23 | 9 | 1 |
| α-helix | 27-34 | 8 | |
| α-helix | 36-39 | 4 | |
| α-helix | 41-68 | 28 | |
| α-helix | 75-88 | 14 | |
| α-helix | 92-115 | 24 | |
| α-helix | 118-121 | 4 | |
| α-helix | 125-127 | 3 | |
| α-helix | 135-136 | 2 | |
| α-helix | 137-142 | 6 | |
| α-helix | 162-171 | 10 | |
| α-helix | 176-179 | 4 | |
| α-helix | 180-190 | 11 | |
| α-helix | 199-200 | 2 | |
| α-helix | 201-207 | 7 | |
| α-helix | 208-224 | 17 | |
| α-helix | 233-237 | 5 | |
| α-helix | 260-263 | 4 | |
| α-helix | 266-269 | 4 | |
| α-helix | 275-286 | 12 | |
| α-helix | 296-298 | 3 | |
| α-helix | 300-310 | 11 | |
| α-helix | 321-327 | 7 | |
| α-helix | 347-355 | 9 | |
| α-helix | 356-360 | 5 | |
| α-helix | 370-381 | 12 | |
| β-strand | 392-394 | 3 | 2 |
| α-helix | 397-406 | 10 | |
| α-helix | 412-420 | 9 | |
| α-helix | 421-425 | 5 | |
| α-helix | 444-447 | 4 | |
| β-strand | 450-452 | 3 | 2 |
| α-helix | 453-463 | 11 | |
| α-helix | 481-498 | 18 | |
| α-helix | 501-506 | 6 | |
| β-strand | 516 | 1 | 3 |
| β-strand | 519 | 1 | 3 |
| α-helix | 521-537 | 17 | |
| α-helix | 565-571 | 7 | |
| α-helix | 576-587 | 12 | |
| β-strand | 595-597 | 3 | 1 |
| α-helix | 614-617 | 4 | |
| β-strand | 619-624 | 6 | 1 |
| β-strand | 627-632 | 6 | 1 |
| α-helix | 643-647 | 5 | |
| β-strand | 654-660 | 7 | 1 |
| α-helix | 669-673 | 5 | |
| α-helix | 683-685 | 3 | |
| α-helix | 686-694 | 9 | |
| α-helix | 703-704 | 2 | |
| α-helix | 714-717 | 4 | |
| α-helix | 718-720 | 3 | |
| α-helix | 721-725 | 5 | |
| α-helix | 726-730 | 5 | |
| α-helix | 741-743 | 3 | |
| α-helix | 744-746 | 3 | |
| α-helix | 750-760 | 11 | |
| β-strand | 763-769 | 7 | 1 |
| α-helix | 772-780 | 9 | |
| β-strand | 785-789 | 5 | 1 |
| α-helix | 791-793 | 3 | |
| α-helix | 803-809 | 7 | |
| α-helix | 814-818 | 5 | |
| β-strand | 822-824 | 3 | 1 |
| β-strand | 829-833 | 5 | 1 |
| β-strand | 849-850 | 2 | 4 |
| β-strand | 860-861 | 2 | 4 |
| β-strand | 877-886 | 10 | 1 |
| α-helix | 896-904 | 9 | |
| β-strand | 912-917 | 6 | 5 |
| β-strand | 925-929 | 5 | 5 |
| β-strand | 935-940 | 6 | 5 |
| β-strand | 943-944 | 2 | 6 |
| β-strand | 951-952 | 2 | 6 |
| α-helix | 953-960 | 8 | |
| α-helix | 968-970 | 3 | |
| α-helix | 976-997 | 22 | |
| β-strand | 1001-1007 | 7 | 5 |
| α-helix | 1025-1034 | 10 | |
| β-strand | 1038 | 1 | 7 |
| α-helix | 1044 | 1 | |
| β-strand | 1048 | 1 | 8 |
| β-strand | 1053 | 1 | 8 |
| β-strand | 1055 | 1 | 7 |
| α-helix | 1059-1061 | 3 | |
| β-strand | 1070 | 1 | 5 |
| β-strand | 1075-1078 | 4 | 5 |
| α-helix | 1102-1111 | 10 | |
| β-strand | 1114 | 1 | 9 |
| β-strand | 1117 | 1 | 10 |
| β-strand | 1124 | 1 | 10 |
| β-strand | 1125-1129 | 5 | 9 |
| α-helix | 1130-1133 | 4 | |
| β-strand | 1141-1145 | 5 | 9 |
| α-helix | 1170-1172 | 3 | |
| α-helix | 1175-1180 | 6 | |
| α-helix | 1192-1197 | 6 | |
| α-helix | 1201-1212 | 12 | |
| β-strand | 1218 | 1 | 11 |
| β-strand | 1229 | 1 | 11 |
| α-helix | 1243-1245 | 3 | |
| α-helix | 1256-1274 | 19 | |
| α-helix | 1288-1297 | 10 |
| Molecule | Chains | Type | Length | Organism | UniProt |
|---|---|---|---|---|---|
| CRISPR-associated endonuclease Cas12a | A | protein | 1305 | Francisella tularensis subsp. novicida | A0Q7Q2 (AlphaFold model) |
| RNA (31-mer) | B | RNA | 43 | synthetic construct | |
| Ts DNA | C | DNA | 24 | synthetic construct | |
| Nts DNA | D | DNA | 24 | synthetic construct |
>9MKX_1 CRISPR-associated endonuclease Cas12a (chains A) GAASHMSIYQEFVNKYSLSKTLRFELIPQGKTLENIKARGLILDDEKRAKDYKKAKQIID KYHQFFIEEILSSVCISEDLLQNYSDVYFKLKKSDDDNLQKDFKSAKDTIKKQISEYIKD SEKFKNLFNQNLIDAKKGQESDLILWLKQSKDNGIELFKANSDITDIDEALEIIKSFKGW TTYFKGFHENRKNVYSSNDIPTSIIYRIVDDNLPKFLENKAKYESLKDKAPEAINYEQIK KDLAEELTFDIDYKTSEVNQRVFSLDEVFEIANFNNYLNQSGITKFNTIIGGKFVNGENT KRKGINEYINLYSQQINDKTLKKYKMSVLFKQILSDTESKSFVIDKLEDDSDVVTTMQSF YEQIAAFKTVEEKSIKETLSLLFDDLKAQKLDLSKIYFKNDKSLTDLSQQVFDDYSVIGT AVLEYITQQIAPKNLDNPSKKEQELIAKKTEKAKYLSLETIKLALEEFNKHRDIDKQCRF EEILANFAAIPMIFDEIAQNKDNLAQISIKYQNQGKKDLLQASAEDDVKAIKDLLDQTNN LLHKLKIFHISQSEDKANILDKDEHFYLVFEECYFELANIVPLYNKIRNYITQKPYSDEK FKLNFENSTLANGWDKNKEPDNTAILFIKDDKYYLGVMNKKNNKIFDDKAIKENKGEGYK KIVYKLLPGANKMLPKVFFSAKSIKFYNPSEDILRIRNHSTHTKNGSPQKGYEKFEFNIE DCRKFIDFYKQSISKHPEWKDFGFRFSDTQRYNSIDEFYREVENQGYKLTFENISESYID SVVNQGKLYLFQIYNKDFSAYSKGRPNLHTLYWKALFDERNLQDVVYKLNGEAELFYRKQ SIPKKITHPAKEAIANKNKDNPKKESVFEYDLIKDKRFTEDKFFFHCPITINFKSSGANK FNDEINLLLKEKANDVHILSIDRGERHLAYYTLVDGKGNIIKQDTFNIIGNDRMKTNYHD KLAAIEKDRDSARPPWKKINNIKEMKEGYLSQVVHEIAKLVIEYNAIVVFEDLNFGFKRG RFKVEKQVYQKLEKMLIEKLNYLVFKDNEFDKTGGVLRAYQLTAPFETFKKMGKQTGIIY YVPAGFTSKICPVTGFVNQLYPKYESVSKSQEFFSKFDKICYNLDKGYFEFSFDYKNFGD KAAKGKWTIASFGSRLINFRNSDKNHNWDTREVYPTKELEKLLKDYSIEYGHGECIKAAI CGESDKKFFAKLTSVLNTILQMRNSKTGTELDYLISPVADVNGNFFDSRQAPKNMPQDAD ANGAYHIGLKGLMLLGRIKNNQEGKKLNLVIKNEEYFEFVQNRNN
>9MKX_2 RNA (31-MER) (chains B) AAUUUCUACUGUUGUAGAUGAGAAGUCAUUUAAUAAGGCCACU
>9MKX_3 TS DNA (chains C) GCCTTATTAAATGACTTCTCTAAA
>9MKX_4 NTS DNA (chains D) TTTAGAGAAGTCATTTAATAAGGC
Bridge helix of Cas12a is an allosteric regulator of R-loop formation and RuvC activation. Ganguly, C., Aribam, S.D., Dos Santos, A.M. et al. Nat Commun (2026) 17. DOI 10.1038/s41467-026-68657-0 · PubMed
Other PDB entries of the same protein (UniProt A0Q7Q2 (AlphaFold model), which also has an AlphaFold model), best resolution first:
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