1
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Patel MB, Griffin PJ, Olson SF, Dai J, Hou Y, Malik T, Das P, Zhang G, Zhao W, Witman GB, Lechtreck KF. Distribution and bulk flow analyses of the intraflagellar transport (IFT) motor kinesin-2 support an "on-demand" model for Chlamydomonas ciliary length control. Cytoskeleton (Hoboken) 2024. [PMID: 38456596 DOI: 10.1002/cm.21851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/09/2024]
Abstract
Most cells tightly control the length of their cilia. The regulation likely involves intraflagellar transport (IFT), a bidirectional motility of multi-subunit particles organized into trains that deliver building blocks into the organelle. In Chlamydomonas, the anterograde IFT motor kinesin-2 consists of the motor subunits FLA8 and FLA10 and the nonmotor subunit KAP. KAP dissociates from IFT at the ciliary tip and diffuses back to the cell body. This observation led to the diffusion-as-a-ruler model of ciliary length control, which postulates that KAP is progressively sequestered into elongating cilia because its return to the cell body will require increasingly more time, limiting motor availability at the ciliary base, train assembly, building block supply, and ciliary growth. Here, we show that Chlamydomonas FLA8 also returns to the cell body by diffusion. However, more than 95% of KAP and FLA8 are present in the cell body and, at a given time, just ~1% of the motor participates in IFT. After repeated photobleaching of both cilia, IFT of fluorescent kinesin subunits continued indicating that kinesin-2 cycles from the large cell-body pool through the cilia and back. Furthermore, growing and full-length cilia contained similar amounts of kinesin-2 subunits and the size of the motor pool at the base changed only slightly with ciliary length. These observations are incompatible with the diffusion-as-a-ruler model, but rather support an "on-demand model," in which the cargo load of the trains is regulated to assemble cilia of the desired length.
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Affiliation(s)
- Mansi B Patel
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Paul J Griffin
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Spencer F Olson
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Jin Dai
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Yuqing Hou
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Tara Malik
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Poulomi Das
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Gui Zhang
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Winston Zhao
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - George B Witman
- Department of Radiology, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Karl F Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
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2
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Rao VG, Shendge AA, D'Gama PP, Martis EAF, Mehta S, Coutinho EC, D'Souza JS. A-kinase anchoring proteins are enriched in the central pair microtubules of motile cilia in Chlamydomonas reinhardtii. FEBS Lett 2024; 598:457-476. [PMID: 38140814 DOI: 10.1002/1873-3468.14791] [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: 03/13/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 12/24/2023]
Abstract
Cilia are microtubule-based sensory organelles present in a number of eukaryotic cells. Mutations in the genes encoding ciliary proteins cause ciliopathies in humans. A-kinase anchoring proteins (AKAPs) tether ciliary signaling proteins such as protein kinase A (PKA). The dimerization and docking domain (D/D) on the RIIα subunit of PKA interacts with AKAPs. Here, we show that AKAP240 from the central-pair microtubules of Chlamydomonas reinhardtii cilia uses two C-terminal amphipathic helices to bind to its partner FAP174, an RIIα-like protein with a D/D domain at the N-terminus. Co-immunoprecipitation using anti-FAP174 antibody with an enriched central-pair microtubule fraction isolated seven interactors whose mass spectrometry analysis revealed proteins from the C2a (FAP65, FAP70, and FAP147) and C1b (CPC1, HSP70A, and FAP42) microtubule projections and FAP75, a protein whose sub-ciliary localization is unknown. Using RII D/D and FAP174 as baits, we identified two additional AKAPs (CPC1 and FAP297) in the central-pair microtubules.
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Affiliation(s)
- Venkatramanan G Rao
- School of Biological Sciences, UM-DAE Centre for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Amruta A Shendge
- School of Biological Sciences, UM-DAE Centre for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Percival P D'Gama
- School of Biological Sciences, UM-DAE Centre for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Elvis A F Martis
- Molecular Simulations Group, Department of Pharmaceutical Chemistry, Bombay College of Pharmacy, Santacruz (E), Mumbai, India
| | - Shraddha Mehta
- School of Biological Sciences, UM-DAE Centre for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Evans C Coutinho
- Molecular Simulations Group, Department of Pharmaceutical Chemistry, Bombay College of Pharmacy, Santacruz (E), Mumbai, India
- St John Institute of Pharmacy and Research, Palghar (E), Maharashtra, India
| | - Jacinta S D'Souza
- School of Biological Sciences, UM-DAE Centre for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
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3
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Larson BT. Perspectives on Principles of Cellular Behavior from the Biophysics of Protists. Integr Comp Biol 2023; 63:1405-1421. [PMID: 37496203 PMCID: PMC10755178 DOI: 10.1093/icb/icad106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 07/14/2023] [Accepted: 07/17/2023] [Indexed: 07/28/2023] Open
Abstract
Cells are the fundamental unit of biological organization. Although it may be easy to think of them as little more than the simple building blocks of complex organisms such as animals, single cells are capable of behaviors of remarkable apparent sophistication. This is abundantly clear when considering the diversity of form and function among the microbial eukaryotes, the protists. How might we navigate this diversity in the search for general principles of cellular behavior? Here, we review cases in which the intensive study of protists from the perspective of cellular biophysics has driven insight into broad biological questions of morphogenesis, navigation and motility, and decision making. We argue that applying such approaches to questions of evolutionary cell biology presents rich, emerging opportunities. Integrating and expanding biophysical studies across protist diversity, exploiting the unique characteristics of each organism, will enrich our understanding of general underlying principles.
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Affiliation(s)
- Ben T Larson
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158, USA
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4
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Han L, Rao Q, Yang R, Wang Y, Chai P, Xiong Y, Zhang K. Cryo-EM structure of an active central apparatus. Nat Struct Mol Biol 2022; 29:472-482. [PMID: 35578022 PMCID: PMC9113940 DOI: 10.1038/s41594-022-00769-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/30/2022] [Indexed: 12/13/2022]
Abstract
Accurately regulated ciliary beating in time and space is critical for diverse cellular activities, which impact the survival and development of nearly all eukaryotic species. An essential beating regulator is the conserved central apparatus (CA) of motile cilia, composed of a pair of microtubules (C1 and C2) associated with hundreds of protein subunits per repeating unit. It is largely unclear how the CA plays its regulatory roles in ciliary motility. Here, we present high-resolution structures of Chlamydomonas reinhardtii CA by cryo-electron microscopy (cryo-EM) and its dynamic conformational behavior at multiple scales. The structures show how functionally related projection proteins of CA are clustered onto a spring-shaped scaffold of armadillo-repeat proteins, facilitated by elongated rachis-like proteins. The two halves of the CA are brought together by elastic chain-like bridge proteins to achieve coordinated activities. We captured an array of kinesin-like protein (KLP1) in two different stepping states, which are actively correlated with beating wave propagation of cilia. These findings establish a structural framework for understanding the role of the CA in cilia.
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Affiliation(s)
- Long Han
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Qinhui Rao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Renbin Yang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Center for Molecular Microscopy, Frederick National Laboratory for Cancer Research, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Yue Wang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Pengxin Chai
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Kai Zhang
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
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5
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Chen J, Li Y, Li M, Shi J, Wang L, Luo S, Liu H. Chemical Flocculation-Based Green Algae Materials for Photobiological Hydrogen Production. ACS APPLIED BIO MATERIALS 2022; 5:897-903. [PMID: 35080839 DOI: 10.1021/acsabm.1c01281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Photobiological hydrogen production is among the most promising ways toward the mass production of hydrogen energy. The use of green algal aggregates to produce photobiological hydrogen has attracted much attention because it overcomes the limitations of sulfur deprivation and oxygen scavengers. However, the current preparation of green algal aggregates that are capable of hydrogen production is time-consuming and laborious, leading to a difficulty in large-scale applications. Here, we demonstrated that the chemical flocculation of green algae is able to generate aggregates for photobiological hydrogen production. We find that Chlorella pyrenoidosa can directly form aggregates in the original liquid cultures by a commercial chemical flocculant, cationic etherified starch, thereby achieving sustainable hydrogen production for 11 days under continuous light irradiation, and the average rate of photobiological production reaches 0.37 μmol H2 (mg chlorophyll·h)-1. This research provides a feasible approach for preparing a low-cost photobiological hydrogen production system helping to realize carbon neutrality.
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Affiliation(s)
- Jie Chen
- School of Chemical Science and Engineering, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai 200092, China
| | - Yujie Li
- School of Chemical Science and Engineering, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai 200092, China.,Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Mingrui Li
- School of Chemical Science and Engineering, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai 200092, China
| | - Jiye Shi
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Lihua Wang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
| | - Shihua Luo
- Department of Traumatology, Rui Jin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Huajie Liu
- School of Chemical Science and Engineering, Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Shanghai Research Institute for Intelligent Autonomous Systems, Tongji University, Shanghai 200092, China
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6
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Global asymptotic stability of the active disassembly model of flagellar length control. J Math Biol 2021; 84:8. [PMID: 34970717 PMCID: PMC8802998 DOI: 10.1007/s00285-021-01709-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 09/10/2021] [Accepted: 12/10/2021] [Indexed: 01/01/2023]
Abstract
Organelle size control is a fundamental question in biology that demonstrates the fascinating ability of cells to maintain homeostasis within their highly variable environments. Theoretical models describing cellular dynamics have the potential to help elucidate the principles underlying size control. Here, we perform a detailed study of the active disassembly model proposed in Fai et al. (elife 8:e42599, 2019). We construct a hybrid system which is shown to be well-behaved throughout the domain. We rule out the possibility of oscillations arising in the model and prove global asymptotic stability in the case of two flagella by the construction of a suitable Lyapunov function. Finally, we generalize the model to the case of arbitrary flagellar number in order to study olfactory sensory neurons, which have up to twenty cilia per cell. We show that our theoretical results may be extended to this case and explore the implications of this universal mechanism of size control.
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7
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Bauer D, Ishikawa H, Wemmer KA, Hendel NL, Kondev J, Marshall WF. Analysis of biological noise in the flagellar length control system. iScience 2021; 24:102354. [PMID: 33898946 PMCID: PMC8059064 DOI: 10.1016/j.isci.2021.102354] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/16/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023] Open
Abstract
Any proposed mechanism for organelle size control should be able to account not only for average size but also for the variation in size. We analyzed cell-to-cell variation and within-cell variation of length for the two flagella in Chlamydomonas, finding that cell-to-cell variation is dominated by cell size, whereas within-cell variation results from dynamic fluctuations. Fluctuation analysis suggests tubulin assembly is not directly coupled with intraflagellar transport (IFT) and that the observed length fluctuations reflect tubulin assembly and disassembly events involving large numbers of tubulin dimers. Length variation is increased in long-flagella mutants, an effect consistent with theoretical models for flagellar length regulation. Cells with unequal flagellar lengths show impaired swimming but improved gliding, raising the possibility that cells have evolved mechanisms to tune biological noise in flagellar length. Analysis of noise at the level of organelle size provides a way to probe the mechanisms determining cell geometry.
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Affiliation(s)
- David Bauer
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Hiroaki Ishikawa
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Kimberly A. Wemmer
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Nathan L. Hendel
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
| | - Jane Kondev
- Department of Physics, Brandeis University, Abelson-Bass-Yalem Building, 97-301, Waltham, MA, USA
| | - Wallace F. Marshall
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
- Center for Cellular Construction, University of California, San Francisco, 600 16th St., San Francisco, CA, USA
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8
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Fai TG, Mohapatra L, Kar P, Kondev J, Amir A. Length regulation of multiple flagella that self-assemble from a shared pool of components. eLife 2019; 8:e42599. [PMID: 31596235 PMCID: PMC6863624 DOI: 10.7554/elife.42599] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 10/08/2019] [Indexed: 11/24/2022] Open
Abstract
The single-celled green algae Chlamydomonas reinhardtii with its two flagella-microtubule-based structures of equal and constant lengths-is the canonical model organism for studying size control of organelles. Experiments have identified motor-driven transport of tubulin to the flagella tips as a key component of their length control. Here we consider a class of models whose key assumption is that proteins responsible for the intraflagellar transport (IFT) of tubulin are present in limiting amounts. We show that the limiting-pool assumption is insufficient to describe the results of severing experiments, in which a flagellum is regenerated after it has been severed. Next, we consider an extension of the limiting-pool model that incorporates proteins that depolymerize microtubules. We show that this 'active disassembly' model of flagellar length control explains in quantitative detail the results of severing experiments and use it to make predictions that can be tested in experiments.
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Affiliation(s)
- Thomas G Fai
- Department of MathematicsBrandeis UniversityWalthamUnited States
| | | | - Prathitha Kar
- Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeUnited States
| | - Jane Kondev
- Department of PhysicsBrandeis UniversityWalthamUnited States
| | - Ariel Amir
- Paulson School of Engineering and Applied SciencesHarvard UniversityCambridgeUnited States
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9
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Bottier M, Thomas KA, Dutcher SK, Bayly PV. How Does Cilium Length Affect Beating? Biophys J 2019; 116:1292-1304. [PMID: 30878201 PMCID: PMC6451027 DOI: 10.1016/j.bpj.2019.02.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 01/23/2019] [Accepted: 02/13/2019] [Indexed: 12/21/2022] Open
Abstract
The effects of cilium length on the dynamics of cilia motion were investigated by high-speed video microscopy of uniciliated mutants of the swimming alga, Chlamydomonas reinhardtii. Cells with short cilia were obtained by deciliating cells via pH shock and allowing cilia to reassemble for limited times. The frequency of cilia beating was estimated from the motion of the cell body and of the cilium. Key features of the ciliary waveform were quantified from polynomial curves fitted to the cilium in each image frame. Most notably, periodic beating did not emerge until the cilium reached a critical length between 2 and 4 μm. Surprisingly, in cells that exhibited periodic beating, the frequency of beating was similar for all lengths with only a slight decrease in frequency as length increased from 4 μm to the normal length of 10-12 μm. The waveform average curvature (rad/μm) was also conserved as the cilium grew. The mechanical metrics of ciliary propulsion (force, torque, and power) all increased in proportion to length. The mechanical efficiency of beating appeared to be maximal at the normal wild-type length of 10-12 μm. These quantitative features of ciliary behavior illuminate the biophysics of cilia motion and, in future studies, may help distinguish competing hypotheses of the underlying mechanism of oscillation.
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Affiliation(s)
- Mathieu Bottier
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri; Department of Genetics, Washington University in St. Louis, St. Louis, Missouri
| | - Kyle A Thomas
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri
| | - Susan K Dutcher
- Department of Genetics, Washington University in St. Louis, St. Louis, Missouri
| | - Philip V Bayly
- Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, Missouri.
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10
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Sequeira MP, Sinha S, Motiwalla MJ, Rao VG, D'Souza JS. Defects in the ratio of the dynein isoform, DHC11 in the long-flagella mutants of Chlamydomonas reinhardtii. Biochem Biophys Res Commun 2017; 482:610-614. [PMID: 27865833 DOI: 10.1016/j.bbrc.2016.11.081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2016] [Accepted: 11/14/2016] [Indexed: 11/16/2022]
Abstract
The long-flagella mutants (lf1, lf2, lf3 and lf4) of Chlamydomonas reinhardtii are defective in proteins that are required for the assembly of normal flagella, their phenotype being long flagella. In a previous study, we biophysically characterized these mutants for their waveform patterns, swimming speeds, beat frequencies and correlated these parameters with their flagellar lengths. We found an anomaly in this correlation and set out to explore the underlying molecular significance, if any. The diverse inner dynein isoforms are the flagellar motors that convert the chemical energy of ATP into the mechanical energy of motility; we probed the presence of one of these isoforms (DHC11, which might help in bend initiation) in the lf mutants and compared it with the wild-type. Our studies show that the ratio of DHC11 is defective in the long-flagella mutants of Chlamydomonas reinhardtii.
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Affiliation(s)
- Marilyn P Sequeira
- UM-DAE Center for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Sapna Sinha
- UM-DAE Center for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Mustafa J Motiwalla
- UM-DAE Center for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Venkatramanan G Rao
- UM-DAE Center for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India
| | - Jacinta S D'Souza
- UM-DAE Center for Excellence in Basic Sciences, Kalina Campus, Santacruz (E), Mumbai, India.
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11
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Rao VG, Sarafdar RB, Chowdhury TS, Sivadas P, Yang P, Dongre PM, D'Souza JS. Myc-binding protein orthologue interacts with AKAP240 in the central pair apparatus of the Chlamydomonas flagella. BMC Cell Biol 2016; 17:24. [PMID: 27287193 PMCID: PMC4901443 DOI: 10.1186/s12860-016-0103-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 06/02/2016] [Indexed: 12/20/2022] Open
Abstract
Background Flagella and cilia are fine thread-like organelles protruding from cells that harbour them. The typical ‘9 + 2’ cilia confer motility on these cells. Although the mechanistic details of motility remain elusive, the dynein-driven motility is regulated by various kinases and phosphatases. A-kinase anchoring proteins (AKAPs) are scaffolds that bind to a variety of such proteins. Usually, they are known to possess a dedicated domain that in vitro interacts with the regulatory subunits (RI and RII) present in the cAMP-dependent protein kinase (PKA) holoenzyme. These subunits conventionally harbour contiguous stretches of a.a. residues that reveal the presence of the Dimerization Docking (D/D) domain, Catalytic interface domain and cAMP-Binding domain. The Chlamydomonas reinhardtii flagella harbour two AKAPs; viz., the radial spoke AKAP97 or RSP3 and the central pair AKAP240. Both these were identified on the basis of their RII-binding property. Interestingly, AKAP97 binds in vivo to two RII-like proteins (RSP7 and RSP11) that contain only the D/D domain. Results We found a Chlamydomonas Flagellar Associated Protein (FAP174) orthologous to MYCBP-1, a protein that binds to organellar AKAPs and Myc onco-protein. An in silico analysis shows that the N-terminus of FAP174 is similar to those RII domain-containing proteins that have binding affinities to AKAPs. Binding of FAP174 was tested with the AKAP97/RSP3 using in vitro pull down assays; however, this binding was rather poor with AKAP97/RSP3. Antibodies were generated against FAP174 and the cellular localization was studied using Western blotting and immunoflourescence in wild type and various flagella mutants. We show that FAP174 localises to the central pair of the axoneme. Using overlay assays we show that FAP174 binds AKAP240 previously identified in the C2 portion of the central pair apparatus. Conclusion It appears that the flagella of Chlamydomonas reinhardtii contain proteins that bind to AKAPs and except for the D/D domain, lack the conventional a.a. stretches of PKA regulatory subunits (RSP7 and RSP11). We add FAP174 to this growing list. Electronic supplementary material The online version of this article (doi:10.1186/s12860-016-0103-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Venkatramanan G Rao
- UM-DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (E), Mumbai, 400098, India
| | - Ruhi B Sarafdar
- UM-DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (E), Mumbai, 400098, India
| | - Twinkle S Chowdhury
- UM-DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (E), Mumbai, 400098, India
| | - Priyanka Sivadas
- Wehr Life Sciences, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201-1881, USA
| | - Pinfen Yang
- Wehr Life Sciences, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201-1881, USA
| | - Prabhakar M Dongre
- Department of Biophysics, University of Mumbai, Kalina campus, Santacruz (E), Mumbai, 400098, India
| | - Jacinta S D'Souza
- UM-DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (E), Mumbai, 400098, India.
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12
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Characterization of salt stress-induced palmelloids in the green alga, Chlamydomonas reinhardtii. ALGAL RES 2016. [DOI: 10.1016/j.algal.2016.03.035] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Sirisha VL, Sinha M, D'Souza JS. Menadione-induced caspase-dependent programmed cell death in the green chlorophyte Chlamydomonas reinhardtii. JOURNAL OF PHYCOLOGY 2014; 50:587-601. [PMID: 26988330 DOI: 10.1111/jpy.12188] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 02/17/2014] [Indexed: 05/19/2023]
Abstract
Menadione, a quinone that undergoes redox cycles leading to the formation of superoxide radicals, induces programmed cell death (PCD) in animals and plants. In this study, we investigated whether the unicellular green alga Chlamydomonas reinhardtii P.A.Dangeard is capable of executing PCD upon exposure to menadione stress. We report here, the morphological, molecular, and biochemical changes after menadione exposure of C. reinhardtii cells. The effect of menadione on cell death has been shown to be dose-dependent; 5-100 μM menadione causes 20%-46% cell death, respectively. It appears that growth is inhibited with the concomitant degradation of the photosynthetic pigments and by a decrease in the photosynthetic capacity. Being an oxidative stress, we found an H2 O2 burst within 15 min of menadione exposure, followed by an increase in antioxidant enzyme (superoxide dismutase [SOD], catalase [CAT], and ascorbate peroxidase [APX]) activities. In parallel, RT-PCR was performed for transcript analyses of Mn-SOD, CAT, and APX. Our results clearly revealed that expression of these genes were up-regulated upon menadione exposure. Furthermore, classical hallmarks of PCD such as alteration of mitochondrial membrane potential, significant increase in caspase-3-like DEVDase activity, cleavage of poly (ADP) ribose polymerase (PARP)-1-like enzyme, and DNA fragmentation as detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and oligosomal DNA fragmentation were observed. Moreover, antibodies against a mammalian active caspase-3 shared epitopes with a caspase-3-like protein of ~17 kDa; its pattern of expression and activity correlated with the onset of cell death. To the best of our knowledge, this is the first report on menadione-induced PCD through a mitochondrian-caspase protease pathway in an algal species.
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Affiliation(s)
- V L Sirisha
- Department of Biology, UM-DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (E), Mumbai, 400 098, India
| | - Mahuya Sinha
- Department of Biology, UM-DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (E), Mumbai, 400 098, India
| | - Jacinta S D'Souza
- Department of Biology, UM-DAE Centre for Excellence in Basic Sciences, Kalina campus, Santacruz (E), Mumbai, 400 098, India
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