MUNI SCI Cytoskeleton RNDr. Jan Škoda, Ph.D. Department of Experimental Biology Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Memory system / All types of cells -System of nucleic acids and proteins (storage and expression of genetic information) Membrane system / All types of cells - quantitative differences -System of biomembranes (flow of matter, energy and information) Cytoskeletal system / Eukaryotes, analogy in prokaryotes -System of filamentous protein structures (motility, spatial organization, communication) 2 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 111 Outline - Cytoskeleton components and main functions -Visualization of the cytoskeleton - Microtubules - Actin filaments (microfilaments) - Intermediary filaments - Nuclear cytoskeleton and cell cortex -Cytoskeleton in prokaryotes 3 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Cytoskeleton components and main functions 04 - Cytoskeleton (23 Mar 2022) nuclear envelope nucleus 5 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Actin filaments (microfilaments) Intermediary filaments Microtubules 7 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Main functions of the cytoskeleton Morphology and structural organization -Animal cell morphology including cytoplasmatic protrusions - Internal organization of the cell - Mechanical strength Movement and locomotion - Intracellular transport - Cytoplasmic streaming - Movement of chromosomes during anaphase -Cell migration - Ciliary and flagellar movement - Muscle contraction 8 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Visualization of the cytoskeleton 9 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Conventional light microscopy - Insufficient contrast -Only microtubules partially observable in some cases, e.g., anaphase/telophase Fluorescence microscopy - Widefield fluorescence microscopy -Confocal microscopy -Super-resolution microscopy Methods of visualization - Fluorochrome-conjugated antibodies (direct and indirect immunofluorescence) - Fluorochrome-conjugated cytoskeletal drugs (poisons) -Tagging proteins with GFP and its derivatives or with mFruit proteins (genetic manipulation) 11 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Fluorescence microscopy Confocal vs. widefield - Pinholes: block out-of-focus signal -Allows optical sectioning: Z-stack, 3D projection Focus Area Background Cell Optical Section Coverslip WIDEFIELD CONFOCAL FLUORESCENCE FLUORESCENCE confocal pinholes objective object not in focal plane object in focal plane 12 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Fluorescence microscopy Super-resolution vs. confocal - Different approaches to overcome diffraction limit (200 nm) - Often faster imaging (widefield microscopy) / Demanding on image processing time Structured Illumination Microscopy (SIM): sample I illumination (unknown) j (known) Moire pattern (raw images) Reconstruction i sample (SIM image) Single-molecule approaches (e.g., STORM): Target structure Localizing activated subset of probes STORM image 13 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Super-resolution fluorescence microscopy Tubulin (confocal, top vs. STORM, bottom) Tubulin, mitochondria (SIM vs widefield) Super-resolution fluorescence microscopy - Superior optical sectioning: 3D reconstruction and projection Actin (Z-positons color-coded; 3D STORM) 15 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Immunofluorescence Tubulin / DNA Alexa Fluor® 488 Anti-tubulin antibody Direct x Indirect ^ Antigen ^ Pnmary Antibody ^ Secondary Antibody Fluorophore Tubulin DNA Primary anti-tubulin antibody & Alexa Fluor® 488 secondary antibody 16 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Fluorochrome-conjugated cytoskeletal drugs - Prevent depolymerization / polymerization (not useful) - Naturally occurring fatal poisons - importance of cytoskeleton dynamics - Phalloidin: Actin filaments -Paclitaxel and derivates: Microtubules 17 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) fl Phalloidin -Toxin found in Amanitaphalloides (death cap mushroom) - Binds F-actin and stabilizes actin filaments i G-actin ( j (ADP-bound) O depolymerisation (-) end polymerisation (+) end ( J G-actin (ATP-bound) ADP-bound ATP-bound \ / F-actin 18 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Phalloidin - visualization of actin filaments ■ Conjugated with modern photostable fluorochromes ■ Straightforward (direct) use as a fluorescent probe Coral_ite®488-Phalloidin, DNA Different Alexa Fluor®-phalloidin conjugates Alexa Fluor® 680 Alexa Fluor® 568 Alexa Fluor® 488 Alexa Fluor® 350 19 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Paclitaxel (brand name: Taxol) -Taxane alkaloid found in Taxus brevifolia (the pacific yew tree) - Induces mitotic arrest / apoptosis (prolonged) 20 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Paclitaxel-based fluorescent probes - Useful for live cell imaging Taxol Janelia Fluor® 646 Lee et al. Angew Chem Int Ed Engl. 2017;56(24):6927-6931. 21 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Tagging proteins with GFP and derivatives -Green Fluorescent Protein - Isolated from Aequorea Victoria (crystal jelly fish) Architecture of Aequorea victoria Green Fluorescent Protein Chromophore Structural Motifs of Green Fluorescent Protein Variants ©f^í? G,y67 ^His66 ^j-^ ECFP I *• f Trp66 Gly67 Gly65 Tyr203 Figure 1 Increased photostability and brightness - EGFP - enhanced green FP EBFP - enhanced blue FP - ECFP - enhanced cyan FP - EYFP - enhanced yellow FP... 22 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Tagging with mFruit proteins Derivatives of DsRed protein cloned from Discosoma striata (radiating mushroom coral) 0 PsRed-Max DsRed^res^ £ E2-Crimson • Q E2-Orange £ EZ-Red/Green tdTamalo RRvT DsRed-Express dimer2 dTomato 0 DsRed.T3 dimerl Ds-,ed"i^ % DsRedM1 £ DsRedZ £ Q DsRed-Timer mRFPI I GGuT -Sips- mGrapeZ rRFP1.T"RFP1.2 mTangerine m honey rJ§#J 0 GRvT ( mGrape3 | mPlum-E16P mRasoberry O mknar«OFIVr,8 £ mStrawben0 PAmCherryl mRFP1.4 U Q mOFP.T.120 rsCherry O O mChěřf^erryRev ^ ^ rsCherr^'Revl.4 RFPr3 O • O mCW^herfc^- mRFP1.5 RDSmCheriy0.1 # # # # fOSmChertyl 0 PAmChe~y2 0 PAmChaj»sSerry2 OOO sfther^BC sfCherr/ 23 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) I CO >» ■o d) _> o > lu TD q) > E £ c c /o CO /y cd it) cd o co co cd S. cd If) \0) cn m co m o cd cm m cd n i h- O CO T- 10 co t5 / cd ' \ h- CD JT \ in m E co m co CO m co m co to m 00 CM co m co in "o q) > Q_ LL O o co m m S (M O CO in in r- n: 00 CO TT m r cd cd r- cm m m 00 cd co o ^ m CM "2 m o a í CO bp co t Tí T O O 00 v^.co ^ o* g UJ LU 25 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) PTM control Actin-GFP 40x 00:00 26 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Microtubules 27 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Microtubular structures - Microtubule network within the cytoplasm - Spindle apparatus (mitotic spindle, meiotic spindle) - Microtubule-organizing center (MTOC) - Primary cilia, motile cilia and flagella - animal cells & their functions - Intracellular transport of cell structures - Movement of chromosomes during anaphase - Cell locomotion - ciliary and flagellar movement; - Cell signaling (primary cilium) - Formation of axons and axon transport 28 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) The structure of microtubules Tubulin -microtubule: a-tubulin & p-tubulin heterodimers - Y-tubulin only in MTOCs - essential for microtubule nucleation Microtubule-organizing center Centrosome (animal cells, some fungi), only y-tubulin ring compl in plant cells; basal bodies (cilium, flagellum) 29 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) GTP-tubulm Protofi lament O GDP-tubulin i* ( , 8 nm 4 nm Plus end 5 1 ^^^^^^^^ GTP CT Growing microtubule Depolymerization Shrinking microtubule Metastable intermediate microtubule Microtubule organization & dynamics -13 protofilaments: polymerization of a/(3-tubulin dimers - Helical structure, 25 nm - Polarization: + end, - end ■ Constant balance of polymerization & depolymerization - Polymerization: hydrolysis of GTP at (3-tubulin -> GDP metastable state Growth/shrinkage: + end - Nucleation: - end 30 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Y-tubulin ring complex: MT nucleation - Minus end of the microtubule MTOCs Centrosomal Centrosome -2 centrioles (mother & daughter) and pericentriolar material -9 triplets of microtubules (A,B,C) -9+0 structure - Duplication during cell cycle: daughter centriole separates -> mother centriole (+) end Microtubule Daughter centriole C tubule B tubule Q/ A tubule Microtubule triplet Distal appendages Interconnecting fibers S phase * G1 phase G2 phase Mother centriole Appendages Subdistal appendages Daughter centriole 32 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 33 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Primary cilium Non-motile cilium, animal cells Basal body = mother centriole, same structure (9 MT triplets, 9+0) Important for cell signaling Microtubules form axoneme: 9 MT doublets, 9+0 Found on nearly every type of cell Most often only one primary cilium Selected cilio pat hies and syndromes (primary cilia) • AlstriJm syndrome (ALMS) • Bardet-Biedl syndrome (BBS) • Jeune syndrome (JATD) • Joubert syndrome UESTS> • Leber's congenital amaurosis (LCA} • Meckel syndrome [MKS) • Nephronophthisis(NPHP) • Orofaciodigital syndrome {OFDSJ • Polycystic kidney disease ÍPKD) • Senior Loken syndrome (SLS) • Usher syndrome (USH) d Ciliary sensing capabilities and selected ciliary signalling pathways • Hedgehog ■i'|n.: in. | *ClassA/B CPCR signalling • WNI signalling + RTK signalling • TGFp/BMP signalling * Notch signalling * ECM receptor signalling * Hippo signalling * niTOR signalling • NF icfi signalling Clathrin-coated vesicle Early enrJosome Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Proteins interacting with microtubules Non-motor proteins: Regulate the stability of microtubules -Microtubule-associated proteins (MAPs): MAPI, MAP2... -Tau proteins - in neurons, stability of axonal microtubules; abnormal phosphorylation -> aggregation in Alzheimer's disease Motor proteins: ATPase activity - Dyneins (movement to - end) - Kinesins (movement to + end) 35 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) fl Microtubule-associated motor proteins -Transport of cargo, ciliary/flagellar movement Dynein movement - Kinesin movement (walking) https ://voutu. be/-7AQ Vbrmz Fw https://voutu.be/v-uuk4Pr2i8 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Motile cilium and flagellum - Similar structure: 9 MT doublets + 2 central singlet MTs, 9+2 - Basal body - centriole - Dynein & nexin linkers - Motile cilia - large numbers (= multiple centrioles), shorter - Flagellum - 1 -3 per cell, longer - Protists, epithelial cells, sperm cells 38 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Mechanism of movement Uynein Plus (+lend Movement of dynein 111 ,|. I gluup I",', ml minus end ol li luhu I' Mimi- i<'itd Ncxin link passive part in motion propeller like ' motion Bending ot IllH UUul'U Ii - back and forth beating -basal body-Flagellum Cilia - ATP-dependent movement of dynein stalks -> bending - Flagellum vs. cilium - wave differences switching dynein activity Direction of motion Direction of motion Inhibited dynein motors (b) Cilia 39 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Actin filaments (microfilaments) (23 Mar 2022) Actin structures - Actin filament network within the cytoplasm -Cell cortex (plasma membrane-associated cytoskeleton) Animal cell-specific structures: -Stress fibers -Cytoplasmic protrusions: microvilli, lamellipodia, filopodia -Contractile ring (cytokinesis) 42 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) The structure of actin filaments Act in -About 5% of cell proteins; different isoforms (major: a,(3,Y) -G-actin (globular): monomeric pool -F-actin (filamentous/fibrillar): polymerized, helical structure-2 strands wound around each other -Actin filament (AF) - thinner, shorter, and more flexible than MT - ! overall length of actin filaments ~ 30* greater than MTs 43 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) AF organization, dynamics & branching depolymerisation G-actin (ADP-bound) (_j end O ADP-bound ATP-bound \ / F-actin O A DP/ATP exchange polymerisation G-actin (+)end (ATP-bound) O - ATP-dependent polymerization - Helical structure, 7 nm - ARP proteins: nucleation & branching Branching ARP protein Actin filamenl consisting of multiple subunits (F^actin) Single actin subunit (G-actin) 44 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Examples of actin structures in animal cells (A) Microvilli (e.g., intestinal enterocytes) (B) Stress fibers: cell adhesion, morphogenesis and mechanotransduction (C) Lamellipodia, filopodia: cell migration (D) Contractile ring: cytokinesis 45 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) fl 47 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 48 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) fl 49 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Functions of actin filaments Cytokinesis (contractile ring) Phagocytosis Cell migration & morphology changes (lamellipodia, filopodia, stress fibers) Substrate interactions - focal adhesions (stress fibers) Oocyte fertilization - acrosomal process formation in sperm cells Muscle contraction Egg cytoplasm - Vitelline layer ,— Plasma membrane Fusion of sperm and egg plasma—* membranes \ Step 1; Binding and exocytosla Step 2: Polymerization of actin Step 3: Fusion of ■perm and egg 51 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Functions of actin filaments -Axon growth (growth cone): nerve synapse formation - Expansion of cell surface - Microvilli - Formation of photoreceptor discs in rods & cones Step 1 TrPr.cK.nC-IIUK.ogy 52 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Growth Cone 10i»m Non-motor proteins associated with AF - Regulate polymerization and spatial organization - Nucleation factors: actin related proteins (ARPs) - Maintaining the pool of (monomeric) G-actin: thymosins - Capping proteins - bind to +end, terminate AF elongation, prevents addition/loss of subunits: ß-actinin, CapZ or Cap32/34 - Proteins stimulating polymerization: profilin - Proteins depolymerizing AF: ADF, cofilin, depactin - Crosslinking protein: filamin, ABP, gelactin, villin, fimbrin, fascin, spectrin, a-actinin - Proteins cutting AF (actin-severing):gelsolin, brevin 53 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Non-motor proteins associated with AF A. Treadmilling Pointed end depolymerization (.• J| ATP ADP JI TT °* Profilin directs actin monomers to barbed ends ATP ADP B. Nucleation Arp2/3 complex ARPC2^ ARPC5 ARPC3 Formin C. Ctosslinking bundling Gelating Bundling D.Capping/Severing Capping (e.g. CAPZct/ß) ft Severing (e.g. cofilin) ( Capping/severing/"* (e.g. gelsolin) ( E. Upstream regulation Phosphatases Cofilin mediated depolymerization Kinase ADP-G actin ATP - actin ADP - actin Filamin • ADF/Cofilin o Profilin • Phospate Fascin 54 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Actin motor proteins Myosins Conventional myosin (type II) - Muscle contraction - regulated by tropomyosin and troponin -Cytokinesis, stress fibers Non-conventional myosins (type I, lll-XVIII) — Vesicular transport (to + or - end) -Maintaining membrane protrusions - Movement of organelles in plant cells Myosfn-3a • Myosins-10 or 15a ---- ft ♦ end transport forces Myosin-1a % ^ Myosin-7a ^^>——^ ■=><=> Adhesion forces Tip complex Myosins ^"""^h Actin bundling protein | a- Adhesion/ and transport forces IS => ■ 55 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Diversity of myosins - Monomeric or dimeric Movement ATP-dependent detachment of myosin head 56 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) IUI Actin-based movement: cell migration Trends in Cell Biology 58 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Mesenchymal migration on 2D surfaces - LamelIipodium with filopodia Ameboid migration in 3D Pseudopod with lamellipodia and filopodia Cell body 4) Contraction and retraction contractile structures actin mesh 59 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 60 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 61 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Actin-based movement: muscle contraction (a) Tropomyosin and troponin work together to block the myosin binding sites on actin. Troponin Tropomyosin Actin Body muscle Calcium ions Myosin binding sites (blocked) (b) When a calcium ion binds to troponin, the troponin-tropomyosin complex moves, exposing myosin binding sites. band Zdisk Sarcomere _I_ Zdisk Myosin Tropomyosin M line Relaxed M +ATP,Ca2t Contracted * CaJ* Calcium ion Troponin-tropomyosin complex, moved 63 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 64 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Intermediary filaments 65 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) The structure of intermediary filaments stiiyyurod |p|MMW o( (wo coiled coil dimers - Present only in animal cells - Many different tissue- and cell type-specific proteins - Polymerization: Fibrillar monomeric peptide (central rod domain) - Homodimers/heterodimers (coiled-coil structure) ■ Tetramer (dimers staggered antiparallel) Protofilament - two packed tetramers - Filament 10 nm - 8 protofilaments; rope-like structure 66 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) fl Classification of intermediary filaments -Type I and II: cytokeratins - Epithelial cells - Associated proteins: filaggrin, plectin, dermoplakin -Type III: vimentin, desmin, GFAP, peripherin - Mesenchymal tissue, muscle cells, neuroglia - Associated proteins: plectin, filensin, epinemin, paranemin -Type IV: neurofilaments, synemin - Neurons; Associated proteins: plectin — Type V: lamins (nuclear lamina, not cytoskeleton) -Type VI: nestin - Neural stem cells, cancer cells, endothelial cells 67 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Kidney cell line Ptk2 Cytokeratin 68 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Functions of intermediary filaments - Increase mechanical strength - Highly stretchable: cell survival under extreme deformations -Shaping cell morphology, localization of organelles - Integrating other components of the cytoskeleton stretching a sheet of cells with intermediate filaments CELLS REMAIN INTACT AND TOGETHER 69 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 71 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Human Ewing's sarcoma cell line Nestin, DNA 72 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Nuclear cytoskeleton & cell cortex 73 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Nucleoskeleton = nuclear lamina -Attached to nuclear envelope: lamina associated polypeptides (LAP1, LAP2), emerin, lamin B-receptor (LBR), MAN1 - Lamin A (alternative splicing: lamin C) & Lamin B -Create fibrous layer; involved in chromatin organization 1 n-rn MOK2 Nucleoplasm Chromatin Nuclear lamina (laminsA, B andC) BAF & HP1 bind to histones 74 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Cell cortex = actin cortex - Cross-linked actin network at the inner face of the plasma membrane -Spectrin (erythrocytes), Spectrin Alpha, Non-Erythrocytic 1 (aka fodrin; other cell types) -Associated proteins: ankyrin - binding to transmembrane proteins protein 4.1 - links spectrin with actin -Morphology maintenance (e.g., erythrocytes) and changes, cell migration 75 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) fl Cell cortex = act in cortex erythrocyte adducin actin filament spectrin tetramer 4____—- band 3—- - a plasma -—»A ^membrane out fflSMfflSffl ■■I adducin^^ H protein 4.1 ankyrin in acting-filament ^ri^*~~—tropomodulin tropomyosin \ spectrin tetramer protein 4.1 complex ankyrin complex Supports otherwise fragile plasma membrane spectrin attachments, proteins actin in •. junctional complex ■ 76 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Cytoskeleton in prokaryotes 77 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Discovered -20 years ago Previously thought bacteria lacked cytoskeleton 1991 - FtsZ protein - tubulin homolog 2001 - MreB and Mbl - actin homolog Snapshot: The Bacterial Cytoskeleton Gero Fink, Andrzej Szewczak-Harris, and Jan Lowe MRC Laboratory of Molecular Biology, Cambridge CB2 OOH. UK Actin homologue MreB regulates cell morphology ARCHITECTURE: 2a(MreBija.r: membrána Tubulin homologue FtsZ controls cell division ARCHITECTURE: FtsA *■: membrane FtsZ™.* DNA segregation ARCHITECTURES: 2P(ParM„,}- and 2p(AlfAilř)-'. 4pfTubZ-ilp)- and 3p(PhuZvr}H Plasmm DMA PavM Cytomotlve lllanwits ol actinlike ParM segregate low-copy m daugnter cefls • ParM forms double-rieicai filament) lhal are oolar and dynarrncalry u"istan,e • A stable bipolar sonOle consists ol • Ftoments of the tubulm homologue TubZ produce pulling force, bul the ■ TubZ is a UeacMllmg 4 stranded filament • AHA and PhuZ are other taamentous DNA-transportng piotems s mechanism Is unknown MnmK facilitates magnetotaxis ARCHITECTURE: 2p(MamKw)'' Magnetospirillum cell Crescentin regulates cell morphology CdvABC and Crennctin make filaments in archaea Other filament systems Architecture Hole Organisms <8TubA, _: BTubAB^jJ'" ? Prosihecobacter ?, tubulin-like Ce« shape Euryarcheota In magnetotactlc bacteria, actn-like tuamenta align magnetic organelles • Forma double faamerrl (rom two par • bkery cytoskeletai a Undergoes rearrangement during cell division Bears resemblance to ntermediate filament protein aohNecturM a Facilitates crescent shape in Caufooacrer • Cytoskeietat filaments lorm close to i • Architecture unknown and filaments The CdvABC system «related to eurtaryoťc ESCRT-W and required lor cei division * Crenactin lorms faamenta similar to actm * The function of crenactin filaments is unknown ARCHITECTURE Number of protofilaments parallel or antiparallel (Monomernucl>[)li0!),,0*m™'',*,: matrix, e.g. 2a(MreB/JP)N: membrane Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) FtsZ - Prokaryotic tubulin homolog -Creates Z-ring structures in the central region of the cell - Mediating cell division - cooperation with FtsA (actin homolog) 79 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) MreB, Mbl, MreBH - Prokaryotic actin homologs -Cell morphology and elongation - Double filaments (antiparallel protofilaments) in proximity of the plasma membrane ParM -Actin homolog -Segregation of low-copy-number plasmids before cytokinesis 80 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) 81 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Crescentin (CreS) - Prokaryotic intermediary filament homolog - Cytoskeletal filaments close to plasma membrane -Crescent (bend) shape: Caulobacter crescentus, Helicobacter pylori C. crescentus C. crescentus Crescentin DNA Crescentin Plasma membrane 82 Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022) Bi1700en Cell Biology / 04 - Cytoskeleton (23 Mar 2022)