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Yao XJ, Chen Q, Yu HP, Ruan DD, Li SJ, Wu M, Liao LS, Lin XF, Fang ZT, Luo JW, Xie BS. A novel splicing mutation DNAH5 c.13,338 + 5G > C is involved in the pathogenesis of primary ciliary dyskinesia in a family with primary familial brain calcification. BMC Pulm Med 2024; 24:343. [PMID: 39014333 PMCID: PMC11251106 DOI: 10.1186/s12890-024-03164-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 07/11/2024] [Indexed: 07/18/2024] Open
Abstract
BACKGROUND Primary ciliary dyskinesia (PCD) is an autosomal recessive hereditary disease characterized by recurrent respiratory infections. In clinical manifestations, DNAH5 (NM_001361.3) is one of the recessive pathogenic genes. Primary familial brain calcification (PFBC) is a neurodegenerative disease characterized by bilateral calcification in the basal ganglia and other brain regions. PFBC can be inherited in an autosomal dominant or recessive manner. A family with PCD caused by a DNAH5 compound heterozygous variant and PFBC caused by a MYORG homozygous variant was analyzed. METHODS In this study, we recruited three generations of Han families with primary ciliary dyskinesia combined with primary familial brain calcification. Their clinical phenotype data were collected, next-generation sequencing was performed to screen suspected pathogenic mutations in the proband and segregation analysis of families was carried out by Sanger sequencing. The mutant and wild-type plasmids were constructed and transfected into HEK293T cells instantaneously, and splicing patterns were detected by Minigene splicing assay. The structure and function of mutations were analyzed by bioinformatics analysis. RESULTS The clinical phenotypes of the proband (II10) and his sister (II8) were bronchiectasis, recurrent pulmonary infection, multiple symmetric calcifications of bilateral globus pallidus and cerebellar dentate nucleus, paranasal sinusitis in the whole group, and electron microscopy of bronchial mucosa showed that the ciliary axoneme was defective. There was also total visceral inversion in II10 but not in II8. A novel splice variant C.13,338 + 5G > C and a frameshift variant C.4314delT (p. Asn1438lysfs *10) were found in the DNAH5 gene in proband (II10) and II8. c.347_348dupCTGGCCTTCCGC homozygous insertion variation was found in the MYORG of the proband. The two pathogenic genes were co-segregated in the family. Minigene showed that DNAH5 c.13,338 + 5G > C has two abnormal splicing modes: One is that part of the intron bases where the mutation site located is translated, resulting in early translation termination of DNAH5; The other is the mutation resulting in the deletion of exon76. CONCLUSIONS The newly identified DNAH5 splicing mutation c.13,338 + 5G > C is involved in the pathogenesis of PCD in the family, and forms a compound heterozygote with the pathogenic variant DNAH5 c.4314delT lead to the pathogenesis of PCD.
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Grants
- 2021J02053, 2023J011159, 2022J01996 Natural Science Foundation of Fujian Province
- 2020-822, 2021-157, 2021-848, 2021-917, 2022-840) Fujian Provincial Finance Department
- 2020-822, 2021-157, 2021-848, 2021-917, 2022-840) Fujian Provincial Finance Department
- 2022CXA001, 2021CXB001, 2022CXB002 Medical Innovation Project of Fujian Province
- National famous and old Chinese medicine experts (Xuemei Zhang, Xiaohua Yan) inheritance studio construction project
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Affiliation(s)
- Xiu-Juan Yao
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
- Respiratory department, Fujian Provincial Hospital, Fuzhou, China
| | - Qian Chen
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
| | - Hong-Ping Yu
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
| | - Dan-Dan Ruan
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
| | - Shi-Jie Li
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
| | - Min Wu
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
| | - Li-Sheng Liao
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
- Department of Hematology, Fujian Provincial Hospital, Fuzhou, China
| | - Xin-Fu Lin
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China
- Pediatrics department, Fujian Provincial Hospital, Fuzhou, China
| | - Zhu-Ting Fang
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China.
- Interventional Department, Fujian Provincial Hospital, Fuzhou, China.
| | - Jie-Wei Luo
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China.
- Department of Traditional Chinese Medicine, Fujian Provincial Hospital, Fuzhou, China.
| | - Bao-Song Xie
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, no. 134 East Street, Fuzhou, 350001, China.
- Respiratory department, Fujian Provincial Hospital, Fuzhou, China.
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Lv Y, Han F, Liu M, Zhang T, Cui G, Wang J, Yang Y, Yang YG, Yang W. Characteristics of N 6-methyladenosine Modification During Sexual Reproduction of Chlamydomonas reinhardtii. GENOMICS, PROTEOMICS & BIOINFORMATICS 2023; 21:756-768. [PMID: 35550876 PMCID: PMC10787120 DOI: 10.1016/j.gpb.2022.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/12/2022] [Accepted: 04/24/2022] [Indexed: 06/15/2023]
Abstract
The unicellular green alga Chlamydomonas reinhardtii (hereafter Chlamydomonas) possesses both plant and animal attributes, and it is an ideal model organism for studying fundamental processes such as photosynthesis, sexual reproduction, and life cycle. N6-methyladenosine (m6A) is the most prevalent mRNA modification, and it plays important roles during sexual reproduction in animals and plants. However, the pattern and function of m6A modification during the sexual reproduction of Chlamydomonas remain unknown. Here, we performed transcriptome and methylated RNA immunoprecipitation sequencing (MeRIP-seq) analyses on six samples from different stages during sexual reproduction of the Chlamydomonas life cycle. The results show that m6A modification frequently occurs at the main motif of DRAC (D = G/A/U, R = A/G) in Chlamydomonas mRNAs. Moreover, m6A peaks in Chlamydomonas mRNAs are mainly enriched in the 3' untranslated regions (3'UTRs) and negatively correlated with the abundance of transcripts at each stage. In particular, there is a significant negative correlation between the expression levels and the m6A levels of genes involved in the microtubule-associated pathway, indicating that m6A modification influences the sexual reproduction and the life cycle of Chlamydomonas by regulating microtubule-based movement. In summary, our findings are the first to demonstrate the distribution and the functions of m6A modification in Chlamydomonas mRNAs and provide new evolutionary insights into m6A modification in the process of sexual reproduction in other plant organisms.
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Affiliation(s)
- Ying Lv
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; China National Botanical Garden, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fei Han
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; China National Botanical Garden, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mengxia Liu
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ting Zhang
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
| | - Guanshen Cui
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China
| | - Jiaojiao Wang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; China National Botanical Garden, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ying Yang
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China; Institute of Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Yun-Gui Yang
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing 100101, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China; Institute of Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Wenqiang Yang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; China National Botanical Garden, Beijing 100093, China; College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China; Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100093, China.
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3
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Rabiasz A, Ziętkiewicz E. Schmidtea mediterranea as a Model Organism to Study the Molecular Background of Human Motile Ciliopathies. Int J Mol Sci 2023; 24:ijms24054472. [PMID: 36901899 PMCID: PMC10002865 DOI: 10.3390/ijms24054472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/21/2023] [Accepted: 02/22/2023] [Indexed: 03/12/2023] Open
Abstract
Cilia and flagella are evolutionarily conserved organelles that form protrusions on the surface of many growth-arrested or differentiated eukaryotic cells. Due to the structural and functional differences, cilia can be roughly classified as motile and non-motile (primary). Genetically determined dysfunction of motile cilia is the basis of primary ciliary dyskinesia (PCD), a heterogeneous ciliopathy affecting respiratory airways, fertility, and laterality. In the face of the still incomplete knowledge of PCD genetics and phenotype-genotype relations in PCD and the spectrum of PCD-like diseases, a continuous search for new causative genes is required. The use of model organisms has been a great part of the advances in understanding molecular mechanisms and the genetic basis of human diseases; the PCD spectrum is not different in this respect. The planarian model (Schmidtea mediterranea) has been intensely used to study regeneration processes, and-in the context of cilia-their evolution, assembly, and role in cell signaling. However, relatively little attention has been paid to the use of this simple and accessible model for studying the genetics of PCD and related diseases. The recent rapid development of the available planarian databases with detailed genomic and functional annotations prompted us to review the potential of the S. mediterranea model for studying human motile ciliopathies.
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Thayyil S, Nishigami Y, Islam MJ, Hashim PK, Furuta K, Oiwa K, Yu J, Yao M, Nakagaki T, Tamaoki N. Dynamic Control of Microbial Movement by Photoswitchable ATP Antagonists. Chemistry 2022; 28:e202200807. [DOI: 10.1002/chem.202200807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Sampreeth Thayyil
- Research Institute for Electronic Science Hokkaido University Kita20, Nishi 10, Kita-ku Sapporo Hokkaido 001-0020 Japan
- Graduate School of Life Science Hokkaido University Kita 10, Nishi 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
| | - Yukinori Nishigami
- Research Institute for Electronic Science Hokkaido University Kita20, Nishi 10, Kita-ku Sapporo Hokkaido 001-0020 Japan
- Graduate School of Life Science Hokkaido University Kita 10, Nishi 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
| | - Md. Jahirul Islam
- Research Institute for Electronic Science Hokkaido University Kita20, Nishi 10, Kita-ku Sapporo Hokkaido 001-0020 Japan
- Graduate School of Life Science Hokkaido University Kita 10, Nishi 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
- Current Address: Institute of Science and Technology Austria 3400 Klosterneuburg Austria
| | - P. K. Hashim
- Research Institute for Electronic Science Hokkaido University Kita20, Nishi 10, Kita-ku Sapporo Hokkaido 001-0020 Japan
- Graduate School of Life Science Hokkaido University Kita 10, Nishi 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
| | - Ken'ya Furuta
- Advanced ICT Research Institute National Institute of Information and Communications Technology Kobe Hyogo 651-2492 Japan
| | - Kazuhiro Oiwa
- Advanced ICT Research Institute National Institute of Information and Communications Technology Kobe Hyogo 651-2492 Japan
| | - Jian Yu
- Faculty of Advanced Life Science Hokkaido University North 10 West 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
| | - Min Yao
- Faculty of Advanced Life Science Hokkaido University North 10 West 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
| | - Toshiyuki Nakagaki
- Research Institute for Electronic Science Hokkaido University Kita20, Nishi 10, Kita-ku Sapporo Hokkaido 001-0020 Japan
- Graduate School of Life Science Hokkaido University Kita 10, Nishi 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
| | - Nobuyuki Tamaoki
- Research Institute for Electronic Science Hokkaido University Kita20, Nishi 10, Kita-ku Sapporo Hokkaido 001-0020 Japan
- Graduate School of Life Science Hokkaido University Kita 10, Nishi 8, Kita-ku Sapporo Hokkaido 060-0810 Japan
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Ndzana FI, Mohamadou A. Exact solitary wavelike solutions in a nonlinear microtubule RLC transmission line. CHAOS (WOODBURY, N.Y.) 2019; 29:013116. [PMID: 30709112 DOI: 10.1063/1.5044722] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 12/07/2018] [Indexed: 06/09/2023]
Abstract
Analytically, we study the dynamics of ionic waves in a microtubule modeled by a nonlinear resistor, inductor, and capacitor (RLC) transmission line. We show through the application of a reductive perturbation technique that the network can be reduced in the continuum limit to the dissipative nonlinear Schrödinger equation. The processes of the modulational instability are studied and, motivated with a solitary wave type of solution to the nonlinear Schrödinger (NLS) equation, we use the direct method and the Weierstrass's elliptic function method to present classes of solitary wavelike solutions to the dissipative NLS equation of the network. The results suggest that microtubules are the biological structures where short-duration nonlinear waves called electrical envelope solitons can be created and propagated. This work presents a good analytical approach of investigating the propagation of solitary waves through a microtubule modeled by a nonlinear RLC transmission line.
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Affiliation(s)
- Fabien Ii Ndzana
- International Center for Complex Systems, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaounde, Cameroon
| | - Alidou Mohamadou
- International Center for Complex Systems, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaounde, Cameroon
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Kollmar M. Fine-Tuning Motile Cilia and Flagella: Evolution of the Dynein Motor Proteins from Plants to Humans at High Resolution. Mol Biol Evol 2016; 33:3249-3267. [PMID: 27880711 PMCID: PMC5100056 DOI: 10.1093/molbev/msw213] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The flagellum is a key innovation linked to eukaryogenesis. It provides motility by regulated cycles of bending and bend propagation, which are thought to be controlled by a complex arrangement of seven distinct dyneins in repeated patterns of outer- (OAD) and inner-arm dynein (IAD) complexes. Electron tomography showed high similarity of this axonemal repeat pattern across ciliates, algae, and animals, but the diversity of dynein sequences across the eukaryotes has not yet comprehensively been resolved and correlated with structural data. To shed light on the evolution of the axoneme I performed an exhaustive analysis of dyneins using the available sequenced genome data. Evidence from motor domain phylogeny allowed expanding the current set of nine dynein subtypes by eight additional isoforms with, however, restricted taxonomic distributions. I confirmed the presence of the nine dyneins in all eukaryotic super-groups indicating their origin predating the last eukaryotic common ancestor. The comparison of the N-terminal tail domains revealed a most likely axonemal dynein origin of the new classes, a group of chimeric dyneins in plants/algae and Stramenopiles, and the unique domain architecture and origin of the outermost OADs present in green algae and ciliates but not animals. The correlation of sequence and structural data suggests the single-headed class-8 and class-9 dyneins to localize to the distal end of the axonemal repeat and the class-7 dyneins filling the region up to the proximal heterodimeric IAD. Tracing dynein gene duplications across the eukaryotes indicated ongoing diversification and fine-tuning of flagellar functions in extant taxa and species.
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Affiliation(s)
- Martin Kollmar
- Department of NMR-Based Structural Biology, Max-Planck-Institute for Biophysical Chemistry, Goettingen, Germany
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7
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Structural Change in the Dynein Stalk Region Associated with Two Different Affinities for the Microtubule. J Mol Biol 2015; 428:1886-96. [PMID: 26585405 DOI: 10.1016/j.jmb.2015.11.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 11/08/2015] [Accepted: 11/09/2015] [Indexed: 12/13/2022]
Abstract
Dynein is a large microtubule-based motor complex that requires tight coupling of intra-molecular ATP hydrolysis with the generation of mechanical force and track-binding activity. However, the microtubule-binding domain is structurally separated by about 15nm from the nucleotide-binding sites by a coiled-coil stalk. Thus, long-range two-way communication is necessary for coordination between the catalytic cycle of ATP hydrolysis and dynein's track-binding affinities. To investigate the structural changes that occur in the dynein stalk region to produce two different microtubule affinities, here we improve the resolution limit of the previously reported structure of the entire stalk region and we investigate structural changes in the dynein stalk and strut/buttress regions by comparing currently available X-ray structures. In the light of recent crystal structures, the basis of the transition from the low-affinity to the high-affinity coiled-coil registry is discussed. A concerted movement model previously reported by Carter and Vale is modified more specifically, and we proposed it as the open zipper model.
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Wilson KS, Gonzalez O, Dutcher SK, Bayly PV. Dynein-deficient flagella respond to increased viscosity with contrasting changes in power and recovery strokes. Cytoskeleton (Hoboken) 2015; 72:477-90. [PMID: 26314933 DOI: 10.1002/cm.21252] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/22/2015] [Accepted: 08/25/2015] [Indexed: 12/24/2022]
Abstract
Changes in the flagellar waveform in response to increased viscosity were investigated in uniflagellate mutants of Chlamydomonas reinhardtii. We hypothesized that the waveforms of mutants lacking different dynein arms would change in different ways as viscosity was increased, and that these variations would illuminate the feedback pathways from force to dynein activity. Previous studies have investigated the effects of viscosity on cell body motion, propulsive force, and power in different mutants, but the effect on waveform has not yet been fully characterized. Beat frequency decreases with viscosity in wild-type uniflagellate (uni1) cells, and outer dynein arm deficient (oda2) mutants. In contrast, the inner dynein arm mutant ida1 (lacking I1/f) maintains beat frequency at high viscosity but alters its flagellar waveform more than either wild-type or oda2. The ida1 waveform is narrower than wild-type, primarily due to an abbreviated recovery stroke; this difference is amplified at high viscosity. The oda2 mutant in contrast, maintains a consistent waveform at high and low viscosity with a slightly longer power stroke than wild-type. Analysis of the delays and shear displacements between bends suggest that direct force feedback in the outer dynein arm system may initiate switching of dynein activity. In contrast, I1/f dynein appears to delay switching, most markedly at the initiation of the power stroke, possibly by controlling inter-doublet separation.
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Affiliation(s)
- Kate S Wilson
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri
| | - Olivia Gonzalez
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri
| | - Susan K Dutcher
- Department of Genetics, Washington University, St. Louis, Missouri
| | - Philip V Bayly
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri
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Nishikawa Y, Oyama T, Kamiya N, Kon T, Toyoshima YY, Nakamura H, Kurisu G. Structure of the entire stalk region of the Dynein motor domain. J Mol Biol 2014; 426:3232-3245. [PMID: 25058684 DOI: 10.1016/j.jmb.2014.06.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 06/12/2014] [Accepted: 06/24/2014] [Indexed: 01/10/2023]
Abstract
Dyneins are large microtubule-based motor complexes that power a range of cellular processes including the transport of organelles, as well as the beating of cilia and flagella. The motor domain is located within the dynein heavy chain and comprises an N-terminal mechanical linker element, a central ring of six AAA+ modules of which four bind or hydrolyze ATP, and a long stalk extending from the AAA+ring with a microtubule-binding domain (MTBD) at its tip. A crucial mechanism underlying the motile activity of cytoskeletal motor proteins is precise coupling between the ATPase and track-binding activities. In dynein, a stalk region consisting of a long (~15nm) antiparallel coiled coil separates these two activities, which must facilitate communication between them. This communication is mediated by a small degree of helix sliding in the coiled coil. However, no high-resolution structure is available of the entire stalk region including the MTBD. Here, we have reported the structure of the entire stalk region of mouse cytoplasmic dynein in a weak microtubule-binding state, which was determined using X-ray crystallography, and have compared it with the dynein motor domain from Dictyostelium discoideum in a strong microtubule-binding state and with a mouse MTBD with its distal portion of the coiled coil fused to seryl-tRNA synthetase from Thermus thermophilus. Our results strongly support the helix-sliding model based on the complete structure of the dynein stalk with a different form of coiled-coil packing. We also propose a plausible mechanism of helix sliding together with further analysis using molecular dynamics simulations. Our results present the importance of conserved proline residues for an elastic motion of stalk coiled coil and imply the manner of change between high-affinity state and low-affinity state of MTBD.
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Affiliation(s)
- Yosuke Nishikawa
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takuji Oyama
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Narutoshi Kamiya
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takahide Kon
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yoko Y Toyoshima
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8902, Japan
| | - Haruki Nakamura
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Genji Kurisu
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan; Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
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Blisnick T, Buisson J, Absalon S, Marie A, Cayet N, Bastin P. The intraflagellar transport dynein complex of trypanosomes is made of a heterodimer of dynein heavy chains and of light and intermediate chains of distinct functions. Mol Biol Cell 2014; 25:2620-33. [PMID: 24989795 PMCID: PMC4148251 DOI: 10.1091/mbc.e14-05-0961] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cilia and flagella are assembled by intraflagellar transport (IFT) of protein complexes that bring tubulin and other precursors to the incorporation site at their distal tip. Anterograde transport is driven by kinesin, whereas retrograde transport is ensured by a specific dynein. In the protist Trypanosoma brucei, two distinct genes encode fairly different dynein heavy chains (DHCs; ∼40% identity) termed DHC2.1 and DHC2.2, which form a heterodimer and are both essential for retrograde IFT. The stability of each heavy chain relies on the presence of a dynein light intermediate chain (DLI1; also known as XBX-1/D1bLIC). The presence of both heavy chains and of DLI1 at the base of the flagellum depends on the intermediate dynein chain DIC5 (FAP133/WDR34). In the IFT140(RNAi) mutant, an IFT-A protein essential for retrograde transport, the IFT dynein components are found at high concentration at the flagellar base but fail to penetrate the flagellar compartment. We propose a model by which the IFT dynein particle is assembled in the cytoplasm, reaches the base of the flagellum, and associates with the IFT machinery in a manner dependent on the IFT-A complex.
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Affiliation(s)
- Thierry Blisnick
- Trypanosome Cell Biology Unit, Institut Pasteur, and Centre National de la Recherche Scientifique URA 2581, 75015 Paris, France
| | - Johanna Buisson
- Trypanosome Cell Biology Unit, Institut Pasteur, and Centre National de la Recherche Scientifique URA 2581, 75015 Paris, France
| | - Sabrina Absalon
- Trypanosome Cell Biology Unit, Institut Pasteur, and Centre National de la Recherche Scientifique URA 2581, 75015 Paris, France
| | - Alexandra Marie
- Trypanosome Cell Biology Unit, Institut Pasteur, and Centre National de la Recherche Scientifique URA 2581, 75015 Paris, France
| | - Nadège Cayet
- Imagopole Platform, Institut Pasteur, 75015 Paris, France
| | - Philippe Bastin
- Trypanosome Cell Biology Unit, Institut Pasteur, and Centre National de la Recherche Scientifique URA 2581, 75015 Paris, France
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Mencarelli C, Mercati D, Dallai R, Lupetti P. Ultrastructure of the sperm axoneme and molecular analysis of axonemal dynein in Ephemeroptera (Insecta). Cytoskeleton (Hoboken) 2014; 71:328-39. [PMID: 24668829 DOI: 10.1002/cm.21175] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 03/13/2014] [Accepted: 03/20/2014] [Indexed: 12/20/2022]
Abstract
The Ephemeroptera sperm axoneme is devoid of outer dynein arms (ODA) and exhibits a pronounced modification of the central pair complex (CPC), which is substituted by the central sheath (CS): a tubular element of unknown molecular composition. We performed a detailed ultrastructural analysis of sperm axonemes in the genera Cloeon and Ecdyonurus using quick-freeze, deep-etch electron microscopy, showing that the loss of the conventional CPC is not only concomitant with the loss of ODA, but also with a substantial modification in the longitudinal distribution of both radial spokes (RS) and inner dynein arms (IDA). Such structures are no longer distributed following the alternation of different repeats as in the 9 + 2 axoneme, but instead share a 32 nm longitudinal repeat: a multiple of the 8 nm repeat observed along the CS wall. Differently from the conventional CPC, the CS and the surrounding RS possess a ninefold symmetry, coherently with the three-dimensional pattern of motility observed in Cloeon free spermatozoa. Biochemical analyses revealed that ultrastructural modifications are concomitant with a reduced complexity of the IDA heavy chain complement. We propose that these structural and molecular modifications might be related to the relief from the evolutionary constraints imposed by the CPC on the basal 9 + 9 + 2 axoneme and could also represent the minimal set compatible with flagellar beating and progressive motility mechanically regulated as suggested by the geometric clutch hypothesis. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Caterina Mencarelli
- Department of Life Sciences, University of Siena, Via Aldo Moro 2, Siena, Italy
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12
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Gleave ES, Schmidt H, Carter AP. A structural analysis of the AAA+ domains in Saccharomyces cerevisiae cytoplasmic dynein. J Struct Biol 2014; 186:367-75. [PMID: 24680784 PMCID: PMC4047620 DOI: 10.1016/j.jsb.2014.03.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/21/2014] [Accepted: 03/22/2014] [Indexed: 11/05/2022]
Abstract
Dyneins are large protein complexes that act as microtubule based molecular motors. The dynein heavy chain contains a motor domain which is a member of the AAA+ protein family (ATPases Associated with diverse cellular Activities). Proteins of the AAA+ family show a diverse range of functionalities, but share a related core AAA+ domain, which often assembles into hexameric rings. Dynein is unusual because it has all six AAA+ domains linked together, in one long polypeptide. The dynein motor domain generates movement by coupling ATP driven conformational changes in the AAA+ ring to the swing of a motile element called the linker. Dynein binds to its microtubule track via a long antiparallel coiled-coil stalk that emanates from the AAA+ ring. Recently the first high resolution structures of the dynein motor domain were published. Here we provide a detailed structural analysis of the six AAA+ domains using our Saccharomycescerevisiae crystal structure. We describe how structural similarities in the dynein AAA+ domains suggest they share a common evolutionary origin. We analyse how the different AAA+ domains have diverged from each other. We discuss how this is related to the function of dynein as a motor protein and how the AAA+ domains of dynein compare to those of other AAA+ proteins.
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Affiliation(s)
- Emma S Gleave
- MRC Laboratory of Molecular Biology, Francis Crick Ave, Cambridge CB2 0QH, UK
| | - Helgo Schmidt
- MRC Laboratory of Molecular Biology, Francis Crick Ave, Cambridge CB2 0QH, UK
| | - Andrew P Carter
- MRC Laboratory of Molecular Biology, Francis Crick Ave, Cambridge CB2 0QH, UK.
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13
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Hendrickson TW, Goss JL, Seaton CA, Rohrs HW. The IC138 and IC140 intermediate chains of the I1 axonemal dynein complex bind directly to tubulin. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3265-3271. [PMID: 24080090 DOI: 10.1016/j.bbamcr.2013.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 09/18/2013] [Accepted: 09/19/2013] [Indexed: 11/17/2022]
Abstract
Dyneins are minus end directed microtubule motors that play a critical role in ciliary and flagellar movement. Ciliary dyneins, also known as axonemal dyneins, are characterized based on their location on the axoneme, either as outer dynein arms or inner dynein arms. The I1 dynein is the best-characterized subspecies of the inner dynein arms; however the interactions between many of the components of the I1 complex and the axoneme are not well defined. In an effort to elucidate the interactions in which the I1 components are involved, we performed zero-length crosslinking on axonemes and studied the crosslinked products formed by the I1 intermediate chains, IC138 and IC140. Our data indicate that IC138 and IC140 bind directly to microtubules. Mass-spectrometry analysis of the crosslinked product identified both α- and β-tubulin as the IC138 and IC140 binding partners. This was further confirmed by crosslinking experiments carried out on purified I1 fractions bound to Taxol-stabilized microtubules. Furthermore, the interaction between IC140 and tubulin is lost when IC138 is absent. Our studies support previous findings that intermediate chains play critical roles in the assembly, axonemal targeting and regulation of the I1 dynein complex.
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Affiliation(s)
| | - Jonathan L Goss
- Department of Biology, Morehouse College, Atlanta, GA 30314, USA
| | - Charles A Seaton
- Department of Biology, Morehouse College, Atlanta, GA 30314, USA; Department of Chemistry, Washington University, St. Louis, MO 63130, USA
| | - Henry W Rohrs
- Department of Chemistry, Washington University, St. Louis, MO 63130, USA
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Oda T, Yagi T, Yanagisawa H, Kikkawa M. Identification of the Outer-Inner Dynein Linker as a Hub Controller for Axonemal Dynein Activities. Curr Biol 2013; 23:656-64. [DOI: 10.1016/j.cub.2013.03.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 03/06/2013] [Accepted: 03/11/2013] [Indexed: 10/27/2022]
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15
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Zheng W. Coarse-grained modeling of the structural states and transition underlying the powerstroke of dynein motor domain. J Chem Phys 2012; 136:155103. [PMID: 22519354 DOI: 10.1063/1.4704661] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
This study aims to model a minimal dynein motor domain capable of motor function, which consists of the linker domain, six AAA+ modules (AAA1-AAA6), coiled coil stalk, and C-terminus domain. To this end, we have used the newly solved X-ray structures of dynein motor domain to perform a coarse-grained modeling of dynein's post- and pre-powerstroke conformation and the conformational transition between them. First, we have used normal mode analysis to identify a single normal mode that captures the coupled motions of AAA1-AAA2 closing and linker domain rotation, which enables the ATP-driven recovery stroke of dynein. Second, based on the post-powerstroke conformation solved crystallographically, we have modeled dynein's pre-powerstroke conformation by computationally inducing AAA1-AAA2 closing and sliding of coiled coil stalk, and the resulting model features a linker domain near the pre-powerstroke position and a slightly tilted stalk. Third, we have modeled the conformational transition from pre- to post-powerstroke conformation, which predicts a clear sequence of structural events that couple microtubule binding, powerstroke and product release, and supports a signaling path from stalk to AAA1 via AAA3 and AAA4. Finally, we have found that a closed AAA3-AAA4 interface (compatible with nucleotide binding) is essential to the mechano-chemical coupling in dynein. Our modeling not only offers unprecedented structural insights to the motor function of dynein as described by past single-molecule, fluorescence resonance energy transfer, and electron microscopy studies, but also provides new predictions for future experiments to test.
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Affiliation(s)
- Wenjun Zheng
- Physics Department, University at Buffalo, Buffalo, New York 14260, USA.
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16
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Kon T, Oyama T, Shimo-Kon R, Imamula K, Shima T, Sutoh K, Kurisu G. The 2.8 Å crystal structure of the dynein motor domain. Nature 2012; 484:345-50. [PMID: 22398446 DOI: 10.1038/nature10955] [Citation(s) in RCA: 181] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 02/17/2012] [Indexed: 01/04/2023]
Abstract
Dyneins are microtubule-based AAA(+) motor complexes that power ciliary beating, cell division, cell migration and intracellular transport. Here we report the most complete structure obtained so far, to our knowledge, of the 380-kDa motor domain of Dictyostelium discoideum cytoplasmic dynein at 2.8 Å resolution; the data are reliable enough to discuss the structure and mechanism at the level of individual amino acid residues. Features that can be clearly visualized at this resolution include the coordination of ADP in each of four distinct nucleotide-binding sites in the ring-shaped AAA(+) ATPase unit, a newly identified interaction interface between the ring and mechanical linker, and junctional structures between the ring and microtubule-binding stalk, all of which should be critical for the mechanism of dynein motility. We also identify a long-range allosteric communication pathway between the primary ATPase and the microtubule-binding sites. Our work provides a framework for understanding the mechanism of dynein-based motility.
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Affiliation(s)
- Takahide Kon
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
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Mohri H, Inaba K, Ishijima S, Baba SA. Tubulin-dynein system in flagellar and ciliary movement. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2012; 88:397-415. [PMID: 23060230 PMCID: PMC3491082 DOI: 10.2183/pjab.88.397] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 08/22/2012] [Indexed: 06/01/2023]
Abstract
Eukaryotic flagella and cilia have attracted the attention of many researchers over the last century, since they are highly arranged organelles and show sophisticated bending movements. Two important cytoskeletal and motor proteins, tubulin and dynein, were first found and described in flagella and cilia. Half a century has passed since the discovery of these two proteins, and much information has been accumulated on their molecular structures and their roles in the mechanism of microtubule sliding, as well as on the architecture, the mechanism of bending movement and the regulation and signal transduction in flagella and cilia. Historical background and the recent advance in this field are described.
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Drosophila Dynein intermediate chain gene, Dic61B, is required for spermatogenesis. PLoS One 2011; 6:e27822. [PMID: 22145020 PMCID: PMC3228723 DOI: 10.1371/journal.pone.0027822] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Accepted: 10/26/2011] [Indexed: 11/19/2022] Open
Abstract
This study reports the identification and characterization of a novel gene, Dic61B, required for male fertility in Drosophila. Complementation mapping of a novel male sterile mutation, ms21, isolated in our lab revealed it to be allelic to CG7051 at 61B1 cytogenetic region, since two piggyBac insertion alleles, CG7051(c05439) and CG7051(f07138) failed to complement. CG7051 putatively encodes a Dynein intermediate chain. All three mutants, ms21, CG7051(c05439) and CG7051(f07138), exhibited absolute recessive male sterility with abnormally coiled sperm axonemes causing faulty sperm individualization as revealed by Phalloidin staining in Don Juan-GFP background. Sequencing of PCR amplicons uncovered two point mutations in ms21 allele and confirmed the piggyBac insertions in CG7051(c05439) and CG7051(f07138) alleles to be in 5'UTR and 4(th) exon of CG7051 respectively, excision of which reverted the male sterility. In situ hybridization to polytene chromosomes demonstrated CG7051 to be a single copy gene. RT-PCR of testis RNA revealed defective splicing of the CG7051 transcripts in mutants. Interestingly, expression of cytoplasmic dynein intermediate chain, α, β, γ tubulins and α-spectrin was normal in mutants while ultra structural studies revealed defects in the assembly of sperm axonemes. Bioinformatics further highlighted the homology of CG7051 to axonemal dynein intermediate chain of various organisms, including DNAI1 of humans, mutations in which lead to male sterility due to immotile sperms. Based on these observations we conclude that CG7051 encodes a novel axonemal dynein intermediate chain essential for male fertility in Drosophila and rename it as Dic61B. This is the first axonemal Dic gene of Drosophila to be characterized at molecular level and shown to be required for spermatogenesis.
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Choi J, Park H, Seok C. How does a registry change in dynein's coiled-coil stalk drive binding of dynein to microtubules? Biochemistry 2011; 50:7629-36. [PMID: 21809817 DOI: 10.1021/bi200834k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dynein is a motor protein that transports cellular cargo along the microtubule (MT) by consuming ATP. Dynein's microtubule-binding domain (MTBD) is separated from the ATP-binding core by a ~15 nm stalk that consists of two α-helices forming an antiparallel coiled coil. It was previously suggested that the coiled-coil stalk creates a registry shift to modulate its binding affinity for MT. A crystal structure of the low-affinity form of MTBD was determined, but that of the high-affinity form with the registry shift is not yet available. In this study, we obtained an all-atom model structure for the high-affinity form of MTBD bound to MT by an anisotropic network model, protein-protein docking, and molecular dynamics simulations. We observe that the magnitude of the coiled-coil helix sliding is dramatically reduced near the two prolines that form the stalk-MTBD boundary and subsequently transformed to cyclic movements of MTBD helices, leading to formation of a new salt bridge with MT at the binding interface. The proposed mechanism explains the roles of highly conserved residues such as the two prolines at the stalk-MTBD boundary, the nonpolar tryptophan and proline residues near the binding interface, and the electropositive residues forming salt bridges with MT.
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Affiliation(s)
- Junghyun Choi
- Department of Chemistry, Seoul National University, Seoul 151-747, Republic of Korea
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21
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Cohen-Krausz S, Cabahug PC, Trachtenberg S. The Monomeric, Tetrameric, and Fibrillar Organization of Fib: The Dynamic Building Block of the Bacterial Linear Motor of Spiroplasma melliferum BC3. J Mol Biol 2011; 410:194-213. [DOI: 10.1016/j.jmb.2011.04.067] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 04/18/2011] [Accepted: 04/27/2011] [Indexed: 10/18/2022]
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Guan J, Ekwurtzel E, Kvist U, Hultenby K, Yuan L. DNAJB13 is a radial spoke protein of mouse '9+2' axoneme. Reprod Domest Anim 2011; 45:992-6. [PMID: 19919626 DOI: 10.1111/j.1439-0531.2009.01473.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
It has been shown that DNAJB13, a type II heat shock protein 40, is highly expressed in the testis and is an axonemal component of mouse mature spermatozoa. By multi-tissue reverse transcription polymerase chain reaction, we found that Dnajb13 gene was expressed not only in the testis but also in several other ciliated cell-containing tissues like brain, lung and oviduct. Immunohistochemistry on mouse trachea and oviduct sections shown that DNAJB13 was present in the motile cilia of those tissues. To define further its localization in the axoneme, immunoelectron microscopy of mouse sperm flagella was performed and shown that DNAJB13 was localized to radial spokes of the axoneme. Taken together, our data indicate that DNAJB13 is a radial spoke protein of the mouse '9+2' axoneme.
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Affiliation(s)
- J Guan
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
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23
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X-ray structure of a functional full-length dynein motor domain. Nat Struct Mol Biol 2011; 18:638-42. [PMID: 21602819 DOI: 10.1038/nsmb.2074] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 04/27/2011] [Indexed: 12/29/2022]
Abstract
Dyneins are large microtubule-based motors that power a wide variety of cellular processes. Here we report a 4.5-Å X-ray crystallographic analysis of the entire functional motor domain of cytoplasmic dynein with ADP from Dictyostelium discoideum, which has revealed the detailed architecture of the functional units required for motor activity, including the ATP-hydrolyzing ring, the long coiled-coil microtubule-binding stalk and the force-generating rod-like linker. We discovered a Y-shaped protrusion composed of two long coiled coils-the stalk and the newly identified 'strut'. This structure supports our model in which the strut coiled coil actively contributes to communication between the primary ATPase site in the ring and the microtubule-binding site at the tip of the stalk coiled coil. Our work also provides insight into how the two motor domains are arranged and how they interact with each other in a functional dimer form of cytoplasmic dynein.
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Vincensini L, Blisnick T, Bastin P. [The importance of model organisms to study cilia and flagella biology]. Biol Aujourdhui 2011; 205:5-28. [PMID: 21501571 DOI: 10.1051/jbio/2011005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Indexed: 12/24/2022]
Abstract
Cilia and flagella are ubiquitous organelles that protrude from the surfaces of many cells, and whose architecture is highly conserved from protists to humans. These complex organelles, composed of over 500 proteins, can be either immotile or motile. They are involved in a myriad of biological processes, including sensing (non-motile cilia) and/or cell motility or movement of extracellular fluids (motile cilia). The ever-expanding list of human diseases linked to defective cilia illustrates the functional importance of cilia and flagella. These ciliopathies are characterised by an impressive diversity of symptoms and an often complex genetic etiology. A precise knowledge of cilia and flagella biology is thus critical to better understand these pathologies. However, multi-ciliated cells are terminally differentiated and difficult to manipulate, and a primary cilium is assembled only when the cell exits from the cell cycle. In this context the use of model organisms, that relies on the high degree of structural but also of molecular conservation of these organelles across evolution, is instrumental to decipher the many facets of cilia and flagella biology. In this review, we highlight the specific strengths of the main model organisms to investigate the molecular composition, mode of assembly, sensing and motility mechanisms and functions of cilia and flagella. Pioneering studies carried out in the green alga Chlamydomonas established the link between cilia and several genetic diseases. Moreover, multicellular organisms such as mouse, zebrafish, Xenopus, C. elegans or Drosophila, and protists like Paramecium, Tetrahymena and Trypanosoma or Leishmania each bring specific advantages to the study of cilium biology. For example, the function of genes involved in primary ciliary dyskinesia (due to defects in ciliary motility) can be efficiently assessed in trypanosomes.
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Affiliation(s)
- Laetitia Vincensini
- Unité de Biologie Cellulaire des Trypanosomes, Institut Pasteur et CNRS URA 2581, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France.
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Kon T, Shima T, Sutoh K. Protein engineering approaches to study the dynein mechanism using a Dictyostelium expression system. Methods Cell Biol 2009; 92:65-82. [PMID: 20409799 DOI: 10.1016/s0091-679x(08)92005-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Dyneins are microtubule-based motor complexes that power a wide variety of motile processes within eukaryotic cells, including the beating of cilia and flagella and intracellular trafficking along microtubules. Mechanistic studies on dynein have been hampered by their enormous size (molecular masses of 0.5-3MDa) and molecular complexity. However, the recent establishment of recombinant expression systems for cytoplasmic dynein, together with structural and functional analyses, has advanced our understanding of the molecular mechanisms of dynein motility. Here, we describe several protocols for protein engineering approaches to the dynein mechanism using a Dictyostelium discoideum expression system. We first describe the design and preparation of recombinant dynein suitable for mechanistic studies. We then discuss two distinct functional assays that take advantage of the recombinant dynein. One is for detection of dynein's conformational changes during the ATPase cycle. Another is an in vitro motility assay at multiple- and single-molecule levels for examination of the dynamic behavior of dynein moving on a microtubule.
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Affiliation(s)
- Takahide Kon
- Department of Life Sciences, University of Tokyo, Japan
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Wirschell M, Yang C, Yang P, Fox L, Yanagisawa HA, Kamiya R, Witman GB, Porter ME, Sale WS. IC97 is a novel intermediate chain of I1 dynein that interacts with tubulin and regulates interdoublet sliding. Mol Biol Cell 2009; 20:3044-54. [PMID: 19420136 DOI: 10.1091/mbc.e09-04-0276] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Our goal is to understand the assembly and regulation of flagellar dyneins, particularly the Chlamydomonas inner arm dynein called I1 dynein. Here, we focus on the uncharacterized I1-dynein IC IC97. The IC97 gene encodes a novel IC without notable structural domains. IC97 shares homology with the murine lung adenoma susceptibility 1 (Las1) protein--a candidate tumor suppressor gene implicated in lung tumorigenesis. Multiple, independent biochemical assays determined that IC97 interacts with both alpha- and beta-tubulin subunits within the axoneme. I1-dynein assembly mutants suggest that IC97 interacts with both the IC138 and IC140 subunits within the I1-dynein motor complex and that IC97 is part of a regulatory complex that contains IC138. Microtubule sliding assays, using axonemes containing I1 dynein but devoid of IC97, show reduced microtubule sliding velocities that are not rescued by kinase inhibitors, revealing a critical role for IC97 in I1-dynein function and control of dynein-driven motility.
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Affiliation(s)
- Maureen Wirschell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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27
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Yagi T, Uematsu K, Liu Z, Kamiya R. Identification of dyneins that localize exclusively to the proximal portion of Chlamydomonas flagella. J Cell Sci 2009; 122:1306-14. [DOI: 10.1242/jcs.045096] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The movements of cilia and flagella are driven by multiple species of dynein heavy chains (DHCs), which constitute inner- and outer-dynein arms. In Chlamydomonas, 11 DHC proteins have been identified in the axoneme, but 14 genes encoding axonemal DHCs are present in the genome. Here, we assigned each previously unassigned DHC gene to a particular DHC protein and found that DHC3, DHC4 and DHC11 encode novel, relatively low abundance DHCs. Immunofluorescence microcopy revealed that DHC11 is localized exclusively to the proximal ∼2 μm region of the ∼12 μm long flagellum. Analyses of growing flagella suggested that DHC3 and DHC4 are also localized to the proximal region. By contrast, the DHC of a previously identified inner-arm dynein, dynein b, displayed an inverse distribution pattern. Thus, the proximal portion of the flagellar axoneme apparently differs in dynein composition from the remaining portion; this difference might be relevant to the special function performed by the flagellar base.
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Affiliation(s)
- Toshiki Yagi
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
- Department of Biological Science, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan
| | - Keigo Uematsu
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - Zhongmei Liu
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
| | - Ritsu Kamiya
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, 113-0033, Japan
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Kon T, Imamula K, Roberts AJ, Ohkura R, Knight PJ, Gibbons IR, Burgess SA, Sutoh K. Helix sliding in the stalk coiled coil of dynein couples ATPase and microtubule binding. Nat Struct Mol Biol 2009; 16:325-33. [PMID: 19198589 PMCID: PMC2757048 DOI: 10.1038/nsmb.1555] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Accepted: 01/05/2009] [Indexed: 01/01/2023]
Abstract
Coupling between ATPase and track binding sites is essential for molecular motors to move along cytoskeletal tracks. In dynein, these sites are separated by a long coiled coil stalk that must mediate communication between them, but the underlying mechanism remains unclear. Here we show that changes in registration between the two helices of the coiled coil can perform this function. We locked the coiled coil at three specific registrations using oxidation to disulfides of paired cysteine residues introduced into the two helices. These trapped ATPase activity either in a microtubule-independent high or low state, and microtubule binding activity either in an ATP-insensitive strong or weak state, depending on the registry of the coiled coil. Our results provide direct evidence that dynein uses sliding between the two helices of the stalk to couple ATPase and microtubule binding activities during its mechanochemical cycle.
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Affiliation(s)
- Takahide Kon
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo 153-8902, Japan
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29
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Roberts AJ, Numata N, Walker ML, Kato YS, Malkova B, Kon T, Ohkura R, Arisaka F, Knight PJ, Sutoh K, Burgess SA. AAA+ Ring and linker swing mechanism in the dynein motor. Cell 2009; 136:485-95. [PMID: 19203583 PMCID: PMC2706395 DOI: 10.1016/j.cell.2008.11.049] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Revised: 10/12/2008] [Accepted: 11/26/2008] [Indexed: 12/22/2022]
Abstract
Dynein ATPases power diverse microtubule-based motilities. Each dynein motor domain comprises a ring-like head containing six AAA+ modules and N- and C-terminal regions, together with a stalk that binds microtubules. How these subdomains are arranged and generate force remains poorly understood. Here, using electron microscopy and image processing of tagged and truncated Dictyostelium cytoplasmic dynein constructs, we show that the heart of the motor is a hexameric ring of AAA+ modules, with the stalk emerging opposite the primary ATPase site (AAA1). The C-terminal region is not an integral part of the ring but spans between AAA6 and near the stalk base. The N-terminal region includes a lever-like linker whose N terminus swings by ∼17 nm during the ATPase cycle between AAA2 and the stalk base. Together with evidence of stalk tilting, which may communicate changes in microtubule binding affinity, these findings suggest a model for dynein's structure and mechanism.
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Affiliation(s)
- Anthony J Roberts
- Astbury Centre for Structural Molecular Biology and Institute of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
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Dea-Ayuela MA, Pérez-Castillo Y, Meneses-Marcel A, Ubeira FM, Bolas-Fernández F, Chou KC, González-Díaz H. HP-Lattice QSAR for dynein proteins: experimental proteomics (2D-electrophoresis, mass spectrometry) and theoretic study of a Leishmania infantum sequence. Bioorg Med Chem 2008; 16:7770-6. [PMID: 18662882 DOI: 10.1016/j.bmc.2008.07.023] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 06/23/2008] [Accepted: 07/02/2008] [Indexed: 10/21/2022]
Abstract
The toxicity and inefficacy of actual organic drugs against Leishmaniosis justify research projects to find new molecular targets in Leishmania species including Leishmania infantum (L. infantum) and Leishmaniamajor (L. major), both important pathogens. In this sense, quantitative structure-activity relationship (QSAR) methods, which are very useful in Bioorganic and Medicinal Chemistry to discover small-sized drugs, may help to identify not only new drugs but also new drug targets, if we apply them to proteins. Dyneins are important proteins of these parasites governing fundamental processes such as cilia and flagella motion, nuclear migration, organization of the mitotic splinde, and chromosome separation during mitosis. However, despite the interest for them as potential drug targets, so far there has been no report whatsoever on dyneins with QSAR techniques. To the best of our knowledge, we report here the first QSAR for dynein proteins. We used as input the Spectral Moments of a Markov matrix associated to the HP-Lattice Network of the protein sequence. The data contain 411 protein sequences of different species selected by ClustalX to develop a QSAR that correctly discriminates on average between 92.75% and 92.51% of dyneins and other proteins in four different train and cross-validation datasets. We also report a combined experimental and theoretic study of a new dynein sequence in order to illustrate the utility of the model to search for potential drug targets with a practical example. First, we carried out a 2D-electrophoresis analysis of L. infantum biological samples. Next, we excised from 2D-E gels one spot of interest belonging to an unknown protein or protein fragment in the region M<20,200 and pI<4. We used MASCOT search engine to find proteins in the L. major data base with the highest similarity score to the MS of the protein isolated from L. infantum. We used the QSAR model to predict the new sequence as dynein with probability of 99.99% without relying upon alignment. In order to confirm the previous function annotation we predicted the sequences as dynein with BLAST and the omniBLAST tools (96% alignment similarity to dyneins of other species). Using this combined strategy, we have successfully identified L. infantum protein containing dynein heavy chain, and illustrated the potential use of the QSAR model as a complement to alignment tools.
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Rompolas P, Pedersen LB, Patel-King RS, King SM. Chlamydomonas FAP133 is a dynein intermediate chain associated with the retrograde intraflagellar transport motor. J Cell Sci 2007; 120:3653-65. [PMID: 17895364 DOI: 10.1242/jcs.012773] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Intraflagellar transport (IFT) is the bi-directional movement of particles along the length of axonemal outer doublet microtubules and is needed for the assembly and maintenance of eukaryotic cilia and flagella. Retrograde IFT requires cytoplasmic dynein 1b, a motor complex whose organization, structural composition and regulation is poorly understood. We have characterized the product of the Chlamydomonas FAP133 gene that encodes a new WD-repeat protein similar to dynein intermediate chains and homologous to the uncharacterized vertebrate protein WD34. FAP133 is located at the peri-basal body region as well as in punctate structures along the flagella. This protein is associated with the IFT machinery because it is specifically depleted from the flagella of cells with defects in anterograde IFT. Fractionation of flagellar matrix proteins indicates that FAP133 associates with both the LC8 dynein light chain and the IFT dynein heavy chain and light intermediate chain (DHC1b-D1bLIC) motor complex. In the absence of DHC1b or D1bLIC, FAP133 fails to localize at the peri-basal body region but, rather, is concentrated in a region of the cytoplasm near the cell center. Furthermore, we found that FAP133, LC8, DHC1b, D1bLIC, the FLA10 kinesin-2 necessary for anterograde IFT and other IFT scaffold components associate to form a large macromolecular assembly.
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Affiliation(s)
- Panteleimon Rompolas
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, CT 06030, USA
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32
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Pedersen LB, Rompolas P, Christensen ST, Rosenbaum JL, King SM. The lissencephaly protein Lis1 is present in motile mammalian cilia and requires outer arm dynein for targeting to Chlamydomonas flagella. J Cell Sci 2007; 120:858-67. [PMID: 17314247 DOI: 10.1242/jcs.03374] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lissencephaly is a developmental brain disorder characterized by a smooth cerebral surface, thickened cortex and misplaced neurons. Classical lissencephaly is caused by mutations in LIS1, which encodes a WD-repeat protein involved in cytoplasmic dynein regulation, mitosis and nuclear migration. Several proteins required for nuclear migration in Aspergillus bind directly to Lis1, including NudC. Mammalian NudC is highly expressed in ciliated epithelia, and localizes to motile cilia in various tissues. Moreover, a NudC ortholog is upregulated upon deflagellation in Chlamydomonas. We found that mammalian Lis1 localizes to motile cilia in trachea and oviduct, but is absent from non-motile primary cilia. Furthermore, we cloned a gene encoding a Lis1-like protein (CrLis1) from Chlamydomonas. CrLis1 is a approximately 37 kDa protein that contains seven WD-repeat domains, similar to Lis1 proteins from other organisms. Immunoblotting using an anti-CrLis1 antibody revealed that this protein is present in the flagellum and is depleted from flagella of mutants with defective outer dynein arm assembly, including one strain that lacks only the alpha heavy chain/light chain 5 thioredoxin complex. Biochemical experiments confirmed that CrLis1 associates with outer dynein arm components and revealed that CrLis1 binds directly to rat NudC. Our results suggest that Lis1 and NudC are present in cilia and flagella and may regulate outer dynein arm activity.
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Affiliation(s)
- Lotte B Pedersen
- Department of Molecular Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen OE, Denmark.
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Kotani N, Sakakibara H, Burgess SA, Kojima H, Oiwa K. Mechanical properties of inner-arm dynein-f (dynein I1) studied with in vitro motility assays. Biophys J 2007; 93:886-94. [PMID: 17496036 PMCID: PMC1913158 DOI: 10.1529/biophysj.106.101964] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Inner-arm dynein-f of Chlamydomonas flagella is a heterodimeric dynein. We performed conventional in vitro motility assays showing that dynein-f translocates microtubules at the comparatively low velocity of approximately 1.2 microm/s. From the dependence of velocity upon the surface density of dynein-f, we estimate its duty ratio to be 0.6-0.7. The relation between microtubule landing rate and surface density of dynein-f are well fitted by the first-power dependence, as expected for a processive motor. At low dynein densities, progressing microtubules rotate erratically about a fixed point on the surface, at which a single dynein-f molecule is presumably located. We conclude that dynein-f has high processivity. In an axoneme, however, slow and processive dynein-f could impede microtubule sliding driven by other fast dyneins (e.g., dynein-c). To obtain insight into the in vivo roles of dynein-f, we measured the sliding velocity of microtubules driven by a mixture of dyneins -c and -f at various mixing ratios. The velocity is modulated as a function of the ratio of dynein-f in the mixture. This modulation suggests that dynein-f acts as a load in the axoneme, but force pushing dynein-f molecules forward seems to accelerate their dissociation from microtubules.
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Affiliation(s)
- Norito Kotani
- Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo 6781297, Japan
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34
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Abstract
Cilia, hair-like structures extending from the cell membrane, perform diverse biological functions. Primary (genetic) defects in the structure and function of sensory and motile cilia result in multiple ciliopathies. The most prominent genetic abnormality involving motile cilia (and the respiratory tract) is primary ciliary dyskinesia (PCD). PCD is a rare, usually autosomal recessive, genetically heterogeneous disorder characterized by sino-pulmonary disease, laterality defects, and male infertility. Ciliary ultrastructural defects are identified in approximately 90% of PCD patients and involve the outer dynein arms, inner dynein arms, or both. Diagnosing PCD is challenging and requires a compatible clinical phenotype together with tests such as ciliary ultrastructural analysis, immunofluorescent staining, ciliary beat assessment, and/or nasal nitric oxide measurements. Recent mutational analysis demonstrated that 38% of PCD patients carry mutations of the dynein genes DNAI1 and DNAH5. Increased understanding of the pathogenesis will aid in better diagnosis and treatment of PCD.
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Affiliation(s)
- Maimoona A Zariwala
- Department of Medicine, Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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Oda T, Hirokawa N, Kikkawa M. Three-dimensional structures of the flagellar dynein-microtubule complex by cryoelectron microscopy. ACTA ACUST UNITED AC 2007; 177:243-52. [PMID: 17438074 PMCID: PMC2064133 DOI: 10.1083/jcb.200609038] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The outer dynein arms (ODAs) of the flagellar axoneme generate forces needed for flagellar beating. Elucidation of the mechanisms underlying the chemomechanical energy conversion by the dynein arms and their orchestrated movement in cilia/flagella is of great importance, but the nucleotide-dependent three-dimensional (3D) movement of dynein has not yet been observed. In this study, we establish a new method for reconstructing the 3D structure of the in vitro reconstituted ODA–microtubule complex and visualize nucleotide-dependent conformational changes using cryoelectron microscopy and image analysis. As the complex went from the rigor state to the relaxed state, the head domain of the β heavy chain shifted by 3.7 nm toward the B tubule and inclined 44° inwards. These observations suggest that there is a mechanism that converts head movement into the axonemal sliding motion.
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Affiliation(s)
- Toshiyuki Oda
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX 75390, USA
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36
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Baron DM, Kabututu ZP, Hill KL. Stuck in reverse: loss of LC1 in Trypanosoma brucei disrupts outer dynein arms and leads to reverse flagellar beat and backward movement. J Cell Sci 2007; 120:1513-20. [PMID: 17405810 DOI: 10.1242/jcs.004846] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Axonemal dyneins are multisubunit molecular motors that provide the driving force for flagellar motility. Dynein light chain 1 (LC1) has been well studied in Chlamydomonas reinhardtii and is unique among all dynein components as the only protein known to bind directly to the catalytic motor domain of the dynein heavy chain. However, the role of LC1 in dynein assembly and/or function is unknown because no mutants have previously been available. We identified an LC1 homologue (TbLC1) in Trypanosoma brucei and have investigated its role in trypanosome flagellar motility using epitope tagging and RNAi studies. TbLC1 is localized along the length of the flagellum and partitions between the axoneme and soluble fractions following detergent and salt extraction. RNAi silencing of TbLC1 gene expression results in the complete loss of the dominant tip-to-base beat that is a hallmark of trypanosome flagellar motility and the concomitant emergence of a sustained reverse beat that propagates base-to-tip and drives cell movement in reverse. Ultrastructure analysis revealed that outer arm dyneins are disrupted in TbLC1 mutants. Therefore LC1 is required for stable dynein assembly and forward motility in T. brucei. Our work provides the first functional analysis of LC1 in any organism. Together with the recent findings in T. brucei DNAI1 mutants [Branche et al. (2006). Conserved and specific functions of axoneme components in trypanosome motility. J. Cell Sci. 119, 3443-3455], our data indicate functionally specialized roles for outer arm dyneins in T. brucei and C. reinhardtii. Understanding these differences will provide a more robust description of the fundamental mechanisms underlying flagellar motility and will aid efforts to exploit the trypanosome flagellum as a drug target.
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Affiliation(s)
- Desiree M Baron
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095, USA
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Krüger R, Wolschin F, Weckwerth W, Bettmer J, Lehmann WD. Plant protein phosphorylation monitored by capillary liquid chromatography--element mass spectrometry. Biochem Biophys Res Commun 2007; 355:89-96. [PMID: 17288992 DOI: 10.1016/j.bbrc.2007.01.108] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2007] [Accepted: 01/22/2007] [Indexed: 10/23/2022]
Abstract
Many essential cellular functions such as growth rate, motility, and metabolic activity are linked to reversible protein phosphorylation, since they are controlled by signaling cascades based mainly on phosphorylation/dephosphorylation events. Quantification of global or site-specific protein phosphorylation is not straightforward with standard proteomic techniques. The coupling of capillary liquid chromatography (microLC) with ICP-MS (inductively coupled plasma-mass spectrometry) is a method which allows a quantitative screening of protein extracts for their phosphorus and sulfur content, and thus provides access to the protein phosphorylation degree. In extension of a recent pilot study, we analyzed protein extracts from the model organisms Arabidopsis thaliana and Chlamydomonas reinhardtii as representatives for multicellular and unicellular green photosynthetically active organisms. The results indicate that the average protein phosphorylation level of the algae C. reinhardtii is higher than that of A. thaliana. Both the average phosphorylation levels were found to be between the extreme values determined so far for prokaryotes (C. glutamicum, lowest levels) and eukaryotes (Mus musculus, highest levels). Tissue samples of A. thaliana representing different stages of plant development showed varying levels of protein phosphorylation indicating a different adjustment of the kinase/phosphatase system. We also utilized the microLC-ICP-MS technology to estimate the efficiency of a novel phosphoprotein enrichment method based on aluminum hydroxide, since the enrichment of phosphorylated species is often an essential step for their molecular characterization.
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Affiliation(s)
- Ralf Krüger
- Central Spectroscopy, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany.
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38
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Wirschell M, Hendrickson T, Sale WS. Keeping an eye on I1: I1 dynein as a model for flagellar dynein assembly and regulation. ACTA ACUST UNITED AC 2007; 64:569-79. [PMID: 17549744 DOI: 10.1002/cm.20211] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Among the major challenges in understanding ciliary and flagellar motility is to determine how the dynein motors are assembled and localized and how dynein-driven outer doublet microtubule sliding is controlled. Diverse studies, particularly in Chlamydomonas, have determined that the inner arm dynein I1 is targeted to a unique structural position and is critical for regulating the microtubule sliding required for normal ciliary/flagellar bending. As described in this review, I1 dynein offers additional opportunities to determine the principles of assembly and targeting of dyneins to cellular locations and for studying the mechanisms that regulate dynein activity and control of motility by phosphorylation.
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Affiliation(s)
- Maureen Wirschell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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39
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Zariwala MA, Leigh MW, Ceppa F, Kennedy MP, Noone PG, Carson JL, Hazucha MJ, Lori A, Horvath J, Olbrich H, Loges NT, Bridoux AM, Pennarun G, Duriez B, Escudier E, Mitchison HM, Chodhari R, Chung EMK, Morgan LC, de Iongh RU, Rutland J, Pradal U, Omran H, Amselem S, Knowles MR. Mutations of DNAI1 in primary ciliary dyskinesia: evidence of founder effect in a common mutation. Am J Respir Crit Care Med 2006. [PMID: 16858015 DOI: 10.1164/rccm.200603-370oc.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Primary ciliary dyskinesia (PCD) is a rare, usually autosomal recessive, genetic disorder characterized by ciliary dysfunction, sino-pulmonary disease, and situs inversus. Disease-causing mutations have been reported in DNAI1 and DNAH5 encoding outer dynein arm (ODA) proteins of cilia. OBJECTIVES We analyzed DNAI1 to identify disease-causing mutations in PCD and to determine if the previously reported IVS1+2_3insT (219+3insT) mutation represents a "founder" or "hot spot" mutation. METHODS Patients with PCD from 179 unrelated families were studied. Exclusion mapping showed no linkage to DNAI1 for 13 families; the entire coding region was sequenced in a patient from the remaining 166 families. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on nasal epithelial RNA in 14 families. RESULTS Mutations in DNAI1 including 12 novel mutations were identified in 16 of 179 (9%) families; 14 harbored biallelic mutations. Deep intronic splice mutations were not identified by reverse transcriptase-polymerase chain reaction. The prevalence of mutations in families with defined ODA defect was 13%; no mutations were found in patients without a defined ODA defect. The previously reported IVS1+2_3insT mutation accounted for 57% (17/30) of mutant alleles, and marker analysis indicates a common founder for this mutation. Seven mutations occurred in three exons (13, 16, and 17); taken together with previous reports, these three exons are emerging as mutation clusters harboring 29% (12/42) of mutant alleles. CONCLUSIONS A total of 10% of patients with PCD are estimated to harbor mutations in DNAI1; most occur as a common founder IVS1+2_3insT or in exons 13, 16, and 17. This information is useful for establishing a clinical molecular genetic test for PCD.
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Affiliation(s)
- Maimoona A Zariwala
- University of North Carolina at Chapel Hill 27599-7248, USA, and Department of Pediatrics and Adolescent Medicine, University Hospital Freiburg, Germany.
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40
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Branche C, Kohl L, Toutirais G, Buisson J, Cosson J, Bastin P. Conserved and specific functions of axoneme components in trypanosome motility. J Cell Sci 2006; 119:3443-55. [PMID: 16882690 DOI: 10.1242/jcs.03078] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Trypanosoma brucei flagellum is unusual as it is attached along the cell body and contains, in addition to an apparently conventional axoneme, a structure called the paraflagellar rod, which is essential for cell motility. Here, we investigated flagellum behaviour in normal and mutant trypanosome cell lines where expression of genes encoding various axoneme proteins (PF16, PF20, DNAI1, LC2) had been silenced by RNAi. First, we show that the propulsive wave (normally used for forward motility) is abolished in the absence of outer dynein arms, whereas the reverse wave (normally used for changing direction) still occurs. Second, in contrast to Chlamydomonas--but like metazoa, the central pair adopts a fixed orientation during flagellum beating. This orientation becomes highly variable in central-pair- and outer-dynein-arm-mutants. Third, the paraflagellar rod contributes to motility by facilitating three-dimensional wave propagation and controlling cell shape. Fourth, motility is required to complete the last stage of cell division in both insect and bloodstream stages of the parasite. Finally, our study also reveals the conservation of molecular components of the trypanosome flagellum. Coupled to the ease of reverse genetics, it raises the interest of trypanosomes as model organisms to study cilia and flagella.
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Affiliation(s)
- Carole Branche
- INSERM U565 and CNRS UMR5153 and MNHN USM0503, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris cedex 05, France
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41
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Zariwala MA, Leigh MW, Ceppa F, Kennedy MP, Noone PG, Carson JL, Hazucha MJ, Lori A, Horvath J, Olbrich H, Loges NT, Bridoux AM, Pennarun G, Duriez B, Escudier E, Mitchison HM, Chodhari R, Chung EMK, Morgan LC, de Iongh RU, Rutland J, Pradal U, Omran H, Amselem S, Knowles MR. Mutations of DNAI1 in primary ciliary dyskinesia: evidence of founder effect in a common mutation. Am J Respir Crit Care Med 2006; 174:858-66. [PMID: 16858015 PMCID: PMC2648054 DOI: 10.1164/rccm.200603-370oc] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Primary ciliary dyskinesia (PCD) is a rare, usually autosomal recessive, genetic disorder characterized by ciliary dysfunction, sino-pulmonary disease, and situs inversus. Disease-causing mutations have been reported in DNAI1 and DNAH5 encoding outer dynein arm (ODA) proteins of cilia. OBJECTIVES We analyzed DNAI1 to identify disease-causing mutations in PCD and to determine if the previously reported IVS1+2_3insT (219+3insT) mutation represents a "founder" or "hot spot" mutation. METHODS Patients with PCD from 179 unrelated families were studied. Exclusion mapping showed no linkage to DNAI1 for 13 families; the entire coding region was sequenced in a patient from the remaining 166 families. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed on nasal epithelial RNA in 14 families. RESULTS Mutations in DNAI1 including 12 novel mutations were identified in 16 of 179 (9%) families; 14 harbored biallelic mutations. Deep intronic splice mutations were not identified by reverse transcriptase-polymerase chain reaction. The prevalence of mutations in families with defined ODA defect was 13%; no mutations were found in patients without a defined ODA defect. The previously reported IVS1+2_3insT mutation accounted for 57% (17/30) of mutant alleles, and marker analysis indicates a common founder for this mutation. Seven mutations occurred in three exons (13, 16, and 17); taken together with previous reports, these three exons are emerging as mutation clusters harboring 29% (12/42) of mutant alleles. CONCLUSIONS A total of 10% of patients with PCD are estimated to harbor mutations in DNAI1; most occur as a common founder IVS1+2_3insT or in exons 13, 16, and 17. This information is useful for establishing a clinical molecular genetic test for PCD.
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Affiliation(s)
- Maimoona A Zariwala
- University of North Carolina at Chapel Hill 27599-7248, USA, and Department of Pediatrics and Adolescent Medicine, University Hospital Freiburg, Germany.
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42
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Wakabayashi KI, King SM. Modulation of Chlamydomonas reinhardtii flagellar motility by redox poise. J Cell Biol 2006; 173:743-54. [PMID: 16754958 PMCID: PMC3207151 DOI: 10.1083/jcb.200603019] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 05/01/2006] [Indexed: 11/28/2022] Open
Abstract
Redox-based regulatory systems are essential for many cellular activities. Chlamydomonas reinhardtii exhibits alterations in motile behavior in response to different light conditions (photokinesis). We hypothesized that photokinesis is signaled by variations in cytoplasmic redox poise resulting from changes in chloroplast activity. We found that this effect requires photosystem I, which generates reduced NADPH. We also observed that photokinetic changes in beat frequency and duration of the photophobic response could be obtained by altering oxidative/reductive stress. Analysis of reactivated cell models revealed that this redox poise effect is mediated through the outer dynein arms (ODAs). Although the global redox state of the thioredoxin-related ODA light chains LC3 and LC5 and the redox-sensitive Ca2+ -binding subunit of the docking complex DC3 did not change upon light/dark transitions, we did observe significant alterations in their interactions with other flagellar components via mixed disulfides. These data indicate that redox poise directly affects ODAs and suggest that it may act in the control of flagellar motility.
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Affiliation(s)
- Ken-ichi Wakabayashi
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, Farmington, CT 06030
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Stephen M. King
- Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, Farmington, CT 06030
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Hornef N, Olbrich H, Horvath J, Zariwala MA, Fliegauf M, Loges NT, Wildhaber J, Noone PG, Kennedy M, Antonarakis SE, Blouin JL, Bartoloni L, Nüsslein T, Ahrens P, Griese M, Kuhl H, Sudbrak R, Knowles MR, Reinhardt R, Omran H. DNAH5 mutations are a common cause of primary ciliary dyskinesia with outer dynein arm defects. Am J Respir Crit Care Med 2006; 174:120-6. [PMID: 16627867 PMCID: PMC2662904 DOI: 10.1164/rccm.200601-084oc] [Citation(s) in RCA: 221] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Primary ciliary dyskinesia (PCD) is characterized by recurrent airway infections and randomization of left-right body asymmetry. To date, autosomal recessive mutations have only been identified in a small number of patients involving DNAI1 and DNAH5, which encode outer dynein arm components. METHODS We screened 109 white PCD families originating from Europe and North America for presence of DNAH5 mutations by haplotype analyses and/or sequencing. RESULTS Haplotype analyses excluded linkage in 26 families. In 30 PCD families, we identified 33 novel (12 nonsense, 8 frameshift, 5 splicing, and 8 missense mutations) and two known DNAH5 mutations. We observed clustering of mutations within five exons harboring 27 mutant alleles (52%) of the 52 detected mutant alleles. Interestingly, 6 (32%) of 19 PCD families with DNAH5 mutations from North America carry the novel founder mutation 10815delT. Electron microscopic analyses in 22 patients with PCD with mutations invariably detected outer dynein arm ciliary defects. High-resolution immunofluorescence imaging of respiratory epithelial cells from eight patients with DNAH5 mutations showed mislocalization of mutant DNAH5 and accumulation at the microtubule organizing centers. Mutant DNAH5 was absent throughout the ciliary axoneme in seven patients and remained detectable in the proximal ciliary axoneme in one patient carrying compound heterozygous splicing mutations at the 3'-end (IVS75-2A>T, IVS76+5G>A). In a preselected subpopulation with documented outer dynein arm defects (n = 47), DNAH5 mutations were identified in 53% of patients. CONCLUSIONS DNAH5 is frequently mutated in patients with PCD exhibiting outer dynein arm defects and mutations cluster in five exons.
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Affiliation(s)
- Nada Hornef
- Department of Pediatrics and Adolescent Medicine, Mathildenstrasse 1, 79106 Freiburg, Germany
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44
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Hozumi A, Satouh Y, Makino Y, Toda T, Ide H, Ogawa K, King SM, Inaba K. Molecular characterization ofCiona sperm outer arm dynein reveals multiple components related to outer arm docking complex protein 2. ACTA ACUST UNITED AC 2006; 63:591-603. [PMID: 16847897 DOI: 10.1002/cm.20146] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Using proteomic and immunochemical techniques, we have identified the light and intermediate chains (IC) of outer arm dynein from sperm axonemes of the ascidian Ciona intestinalis. Ciona outer arm dynein contains six light chains (LC) including a leucine-rich repeat protein, Tctex1- and Tctex2-related proteins, a protein similar to Drosophila roadblock and two components related to Chlamydomonas LC8. No LC with thioredoxin domains is included in Ciona outer arm dynein. Among the five ICs in Ciona, three are orthologs of those in sea urchin dynein: two are WD-repeat proteins and the third one, unique to metazoan sperm flagella, contains both thioredoxin and nucleoside diphosphate kinase modules. The remaining two Ciona ICs have extensive coiled coil structure and show sequence similarity to outer arm dynein docking complex protein 2 (DC2) that was first identified in Chlamydomonas flagella. We recently identified a third DC2-like protein with coiled coil structure, Ci-Axp66.0 that is also associated in substoichiometric amounts with Ciona outer arm dynein. In addition, Oda5p, a component of an additional complex required for assembly of outer arm dynein in Chlamydomonas flagella, also groups with this family of DC2-like proteins. Thus, the assembly of outer arm dynein onto doublet microtubules involves multiple coiled-coil proteins related to DC2.
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Affiliation(s)
- Akiko Hozumi
- Shimoda Marine Research Center, University of Tsukuba, Shizuoka, Japan
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Yamamoto R, Yagi T, Kamiya R. Functional binding of inner-arm dyneins with demembranated flagella ofChlamydomonas mutants. ACTA ACUST UNITED AC 2006; 63:258-65. [PMID: 16518818 DOI: 10.1002/cm.20121] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Experiments were carried out to see if isolated inner arm dyneins could functionally combine with axonemes lacking them. High-salt extract from the axoneme of Chlamydomonas oda1 mutant lacking outer-arm dynein was added to the demembranated cell models of ida1oda1 lacking inner arm dynein f (dynein I1) and outer arm dynein. After incubation, the originally paralyzed ida1oda1 axonemes recovered the ability to beat in the presence of ATP. A similar good motility recovery after incubation with crude oda1 extract was observed in ida9oda2 lacking outer arm and inner arm dynein c, and partial recovery in ida4oda1 lacking outer arm and inner arm species a, c, and d. These observations indicate that dynein f and dynein c can functionally bind with mutant axonemes lacking them. A method for combining isolated inner arm dyneins with axonemes in a functionally active manner should provide a powerful experimental tool with which to study the mechanism of beating.
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Affiliation(s)
- Ryosuke Yamamoto
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Tokyo, Japan
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Yagi T, Minoura I, Fujiwara A, Saito R, Yasunaga T, Hirono M, Kamiya R. An axonemal dynein particularly important for flagellar movement at high viscosity. Implications from a new Chlamydomonas mutant deficient in the dynein heavy chain gene DHC9. J Biol Chem 2005; 280:41412-20. [PMID: 16236707 DOI: 10.1074/jbc.m509072200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ciliary and flagellar axonemes contain multiple inner arm dyneins of which the functional difference is largely unknown. In this study, a Chlamydomonas mutant, ida9, lacking inner arm dynein c was isolated and shown to carry a mutation in the DHC9 dynein heavy chain gene. The cDNA sequence of DHC9 was determined, and its information was used to show that >80% of it is lost in the mutant. Electron microscopy and image analysis showed that the ida9 axoneme lacked electron density near the base of the S2 radial spoke, indicating that dynein c localizes to this site. The mutant ida9 swam only slightly slower than the wild type in normal media. However, swimming velocity was greatly reduced when medium viscosity was modestly increased. Thus, dynein c in wild type axonemes must produce a significant force when flagella are beating in viscous media. Because motility analyses in vitro have shown that dynein c is the fastest among all the inner arm dyneins, we can regard this dynein as a fast yet powerful motor.
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Affiliation(s)
- Toshiki Yagi
- Department of Biological Sciences, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan
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Fliegauf M, Olbrich H, Horvath J, Wildhaber JH, Zariwala MA, Kennedy M, Knowles MR, Omran H. Mislocalization of DNAH5 and DNAH9 in respiratory cells from patients with primary ciliary dyskinesia. Am J Respir Crit Care Med 2005; 171:1343-9. [PMID: 15750039 PMCID: PMC2718478 DOI: 10.1164/rccm.200411-1583oc] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by recurrent infections of the airways and situs inversus in half of the affected offspring. The most frequent genetic defects comprise recessive mutations of DNAH5 and DNAI1, which encode outer dynein arm (ODA) components. Diagnosis of PCD usually relies on electron microscopy, which is technically demanding and sometimes difficult to interpret. METHODS Using specific antibodies, we determined the subcellular localization of the ODA heavy chains DNAH5 and DNAH9 in human respiratory epithelial and sperm cells of patients with PCD and control subjects by high-resolution immunofluorescence imaging. We also assessed cilia and sperm tail function by high-speed video microscopy. RESULTS In normal ciliated airway epithelium, DNAH5 and DNAH9 show a specific regional distribution along the ciliary axoneme, indicating the existence of at least two distinct ODA types. DNAH5 was completely or only distally absent from the respiratory ciliary axoneme in patients with PCD with DNAH5- (n = 3) or DNAI1- (n = 1) mutations, respectively, and instead accumulated at the microtubule-organizing centers. In contrast to respiratory cilia, sperm tails from a patient with DNAH5 mutations had normal ODA heavy chain distribution, suggesting different modes of ODA generation in these cell types. Blinded investigation of a large cohort of patients with PCD and control subjects identified DNAH5 mislocalization in all patients diagnosed with ODA defects by electron microscopy (n = 16). Cilia with complete axonemal DNAH5 deficiency were immotile, whereas cilia with distal DNAH5 deficiency showed residual motility. CONCLUSIONS Immunofluorescence staining can detect ODA defects, which will possibly aid PCD diagnosis.
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Affiliation(s)
- Manfred Fliegauf
- Department of Pediatrics and Adolescent Medicine, Mathildenstrasse 1, 79106 Freiburg, Germany
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Abstract
Eukaryotic cilia and flagella are cytoskeletal organelles that are remarkably conserved from protists to mammals. Their basic unit is the axoneme, a well-defined cylindrical structure composed of microtubules and up to 250 associated proteins. These complex organelles are assembled by a dynamic process called intraflagellar transport. Flagella and cilia perform diverse motility and sensitivity functions in many different organisms. Trypanosomes are flagellated protozoa, responsible for various tropical diseases such as sleeping sickness and Chagas disease. In this review, we first describe general knowledge on the flagellum: its occurrence in the living world, its molecular composition, and its mode of assembly, with special emphasis on the exciting developments that followed the discovery of intraflagellar transport. We then present recent progress regarding the characteristics of the trypanosome flagellum, highlighting the original contributions brought by this organism. The most striking phenomenon is the involvement of the flagellum in several aspects of the trypanosome cell cycle, including cell morphogenesis, basal body migration, and cytokinesis.
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Affiliation(s)
- Linda Kohl
- INSERM U565, CNRS UMR5153, and MNHN USM 0503, Muséum National d'Histoire Naturelle, 75231 Paris, France
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Hendrickson TW, Perrone CA, Griffin P, Wuichet K, Mueller J, Yang P, Porter ME, Sale WS. IC138 is a WD-repeat dynein intermediate chain required for light chain assembly and regulation of flagellar bending. Mol Biol Cell 2004; 15:5431-42. [PMID: 15469982 PMCID: PMC532023 DOI: 10.1091/mbc.e04-08-0694] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Increased phosphorylation of dynein IC IC138 correlates with decreases in flagellar microtubule sliding and phototaxis defects. To test the hypothesis that regulation of IC138 phosphorylation controls flagellar bending, we cloned the IC138 gene. IC138 encodes a novel protein with a calculated mass of 111 kDa and is predicted to form seven WD-repeats at the C terminus. IC138 maps near the BOP5 locus, and bop5-1 contains a point mutation resulting in a truncated IC138 lacking the C terminus, including the seventh WD-repeat. bop5-1 cells display wild-type flagellar beat frequency but swim slower than wild-type cells, suggesting that bop5-1 is altered in its ability to control flagellar waveform. Swimming speed is rescued in bop5-1 transformants containing the wild-type IC138, confirming that BOP5 encodes IC138. With the exception of the roadblock-related light chain, LC7b, all the other known components of the I1 complex, including the truncated IC138, are assembled in bop5-1 axonemes. Thus, the bop5-1 motility phenotype reveals a role for IC138 and LC7b in the control of flagellar bending. IC138 is hyperphosphorylated in paralyzed flagellar mutants lacking radial spoke and central pair components, further indicating a role for the radial spokes and central pair apparatus in control of IC138 phosphorylation and regulation of flagellar waveform.
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Affiliation(s)
- Triscia W Hendrickson
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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DiBella LM, Sakato M, Patel-King RS, Pazour GJ, King SM. The LC7 light chains of Chlamydomonas flagellar dyneins interact with components required for both motor assembly and regulation. Mol Biol Cell 2004; 15:4633-46. [PMID: 15304520 PMCID: PMC519155 DOI: 10.1091/mbc.e04-06-0461] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Revised: 07/09/2004] [Accepted: 07/23/2004] [Indexed: 11/11/2022] Open
Abstract
Members of the LC7/Roadblock family of light chains (LCs) have been found in both cytoplasmic and axonemal dyneins. LC7a was originally identified within Chlamydomonas outer arm dynein and associates with this motor's cargo-binding region. We describe here a novel member of this protein family, termed LC7b that is also present in the Chlamydomonas flagellum. Levels of LC7b are reduced approximately 20% in axonemes isolated from strains lacking inner arm I1 and are approximately 80% lower in the absence of the outer arms. When both dyneins are missing, LC7b levels are diminished to <10%. In oda9 axonemal extracts that completely lack outer arms, LC7b copurifies with inner arm I1, whereas in ida1 extracts that are devoid of I1 inner arms it associates with outer arm dynein. We also have observed that some LC7a is present in both isolated axonemes and purified 18S dynein from oda1, suggesting that it is also a component of both the outer arm and inner arm I1. Intriguingly, in axonemal extracts from the LC7a null mutant, oda15, which assembles approximately 30% of its outer arms, LC7b fails to copurify with either dynein, suggesting that it interacts with LC7a. Furthermore, both the outer arm gamma heavy chain and DC2 from the outer arm docking complex completely dissociate after salt extraction from oda15 axonemes. EDC cross-linking of purified dynein revealed that LC7b interacts with LC3, an outer dynein arm thioredoxin; DC2, an outer arm docking complex component; and also with the phosphoprotein IC138 from inner arm I1. These data suggest that LC7a stabilizes both the outer arms and inner arm I1 and that both LC7a and LC7b are involved in multiple intradynein interactions within both dyneins.
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Affiliation(s)
- Linda M DiBella
- Department of Biochemistry, University of Connecticut Health Center, Farmington, CT 06030-3305, USA
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