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Samant RS, Batista S, Larance M, Ozer B, Milton CI, Bludau I, Wu E, Biggins L, Andrews S, Hervieu A, Johnston HE, Al-Lazikhani B, Lamond AI, Clarke PA, Workman P. Native Size-Exclusion Chromatography-Based Mass Spectrometry Reveals New Components of the Early Heat Shock Protein 90 Inhibition Response Among Limited Global Changes. Mol Cell Proteomics 2023; 22:100485. [PMID: 36549590 PMCID: PMC9898794 DOI: 10.1016/j.mcpro.2022.100485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 11/16/2022] [Accepted: 12/07/2022] [Indexed: 12/24/2022] Open
Abstract
The molecular chaperone heat shock protein 90 (HSP90) works in concert with co-chaperones to stabilize its client proteins, which include multiple drivers of oncogenesis and malignant progression. Pharmacologic inhibitors of HSP90 have been observed to exert a wide range of effects on the proteome, including depletion of client proteins, induction of heat shock proteins, dissociation of co-chaperones from HSP90, disruption of client protein signaling networks, and recruitment of the protein ubiquitylation and degradation machinery-suggesting widespread remodeling of cellular protein complexes. However, proteomics studies to date have focused on inhibitor-induced changes in total protein levels, often overlooking protein complex alterations. Here, we use size-exclusion chromatography in combination with mass spectrometry (SEC-MS) to characterize the early changes in native protein complexes following treatment with the HSP90 inhibitor tanespimycin (17-AAG) for 8 h in the HT29 colon adenocarcinoma cell line. After confirming the signature cellular response to HSP90 inhibition (e.g., induction of heat shock proteins, decreased total levels of client proteins), we were surprised to find only modest perturbations to the global distribution of protein elution profiles in inhibitor-treated HT29 cells at this relatively early time-point. Similarly, co-chaperones that co-eluted with HSP90 displayed no clear difference between control and treated conditions. However, two distinct analysis strategies identified multiple inhibitor-induced changes, including known and unknown components of the HSP90-dependent proteome. We validate two of these-the actin-binding protein Anillin and the mitochondrial isocitrate dehydrogenase 3 complex-as novel HSP90 inhibitor-modulated proteins. We present this dataset as a resource for the HSP90, proteostasis, and cancer communities (https://www.bioinformatics.babraham.ac.uk/shiny/HSP90/SEC-MS/), laying the groundwork for future mechanistic and therapeutic studies related to HSP90 pharmacology. Data are available via ProteomeXchange with identifier PXD033459.
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Affiliation(s)
- Rahul S Samant
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom; Signalling Programme, The Babraham Institute, Cambridge, United Kingdom.
| | - Silvia Batista
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom
| | - Mark Larance
- Centre for Gene Regulation & Expression, University of Dundee, Dundee, United Kingdom
| | - Bugra Ozer
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom
| | - Christopher I Milton
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom
| | - Isabell Bludau
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Estelle Wu
- Signalling Programme, The Babraham Institute, Cambridge, United Kingdom
| | - Laura Biggins
- Bioinformatics Group, The Babraham Institute, Cambridge, United Kingdom
| | - Simon Andrews
- Bioinformatics Group, The Babraham Institute, Cambridge, United Kingdom
| | - Alexia Hervieu
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom
| | - Harvey E Johnston
- Signalling Programme, The Babraham Institute, Cambridge, United Kingdom
| | - Bissan Al-Lazikhani
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom; Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Angus I Lamond
- Centre for Gene Regulation & Expression, University of Dundee, Dundee, United Kingdom
| | - Paul A Clarke
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom
| | - Paul Workman
- Centre for Cancer Drug Discovery, The Institute of Cancer Research, London, United Kingdom.
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2
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The physiological cargo adaptor of kinesin-2 functions as an evolutionary conserved lockpick. Proc Natl Acad Sci U S A 2022; 119:e2109378119. [PMID: 35947619 PMCID: PMC9388150 DOI: 10.1073/pnas.2109378119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Specific recognition of cellular cargo and efficient transport to its correct intracellular destination is an infrastructural challenge faced by most eukaryotic cells. This remarkable deed is accomplished by processive motor proteins that are subject to robust regulatory mechanisms. The first level of regulation entails the ability of the motor to suppress its own activity. This autoinhibition is eventually relieved by specific cargo binding. To better understand the role of the cargo during motor activation, we dissected the activation mechanism of the ciliary homodimeric kinesin-2 from Caenorhabditis elegans by its physiological cargo. In functional reconstitution assays, we identified two cargo adaptor proteins that together are necessary and sufficient to allosterically activate the autoinhibited motor. Surprisingly, the orthologous adaptor proteins from the unicellular green algae Chlamydomonas reinhardtii also fully activated the kinesin-2 from worm, even though C. reinhardtii itself lacks a homodimeric kinesin-2 motor. The latter suggested that a motor activation mechanism similar to the C. elegans model existed already well before metazoans evolved, and prompted us to scrutinize predicted homodimeric kinesin-2 orthologs in other evolutionarily distant eukaryotes. We show that the ciliate Tetrahymena thermophila not only possesses a homodimeric kinesin-2 but that it also shares the same allosteric activation mechanism that we delineated in the C. elegans model. Our results point to a much more fundamental role of homodimeric kinesin-2 in intraflagellar transport (IFT) than previously thought and warrant further scrutiny of distantly related organisms toward a comprehensive picture of the IFT process and its evolution.
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Aiken J, Holzbaur ELF. Cytoskeletal regulation guides neuronal trafficking to effectively supply the synapse. Curr Biol 2021; 31:R633-R650. [PMID: 34033795 DOI: 10.1016/j.cub.2021.02.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The development and proper function of the brain requires the formation of highly complex neuronal circuitry. These circuits are shaped from synaptic connections between neurons and must be maintained over a lifetime. The formation and continued maintenance of synapses requires accurate trafficking of presynaptic and postsynaptic components along the axon and dendrite, respectively, necessitating deliberate and specialized delivery strategies to replenish essential synaptic components. Maintenance of synaptic transmission also requires readily accessible energy stores, produced in part by localized mitochondria, that are tightly regulated with activity level. In this review, we focus on recent developments in our understanding of the cytoskeletal environment of axons and dendrites, examining how local regulation of cytoskeletal dynamics and organelle trafficking promotes synapse-specific delivery and plasticity. These new insights shed light on the complex and coordinated role that cytoskeletal elements play in establishing and maintaining neuronal circuitry.
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Affiliation(s)
- Jayne Aiken
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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4
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Zhao YQ, Mu DL, Wang D, Han YL, Hou CC, Zhu JQ. Analysis of the function of KIF3A and KIF3B in the spermatogenesis in Boleophthalmus pectinirostris. FISH PHYSIOLOGY AND BIOCHEMISTRY 2018; 44:769-788. [PMID: 29511984 DOI: 10.1007/s10695-017-0461-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 12/18/2017] [Indexed: 06/08/2023]
Abstract
Spermatogenesis represents one of the most complicated morphological transformation procedures. During this process, the assembly and maintenance of the flagella and intracellular transport of membrane-bound organelles required KIF3A and KIF3B. Our main goal was to test KIF3A and KIF3B location during spermatogenesis of Boleophthalmus pectinirostris. We cloned complete cDNA of KIF3A/3B from the testis of B. pectinirostris by PCR and rapid amplification of cDNA ends (RACE). The predicted secondary and tertiary structures of B. pectinirostris KIF3A/3B contained three domains: (a) the head region, (b) the stalk region, and (c) the tail region. Real-time quantitative PCR (qPCR) results revealed that KIF3A and KIF3B mRNA were presented in all the tissues examined, with the highest expression seen in the testis. In situ hybridization (ISH) showed that KIF3A and KIF3B were distributed in the periphery of the nuclear in the spermatocyte and the early spermatid. In the late spermatid and mature sperm, the KIF3A and KIF3B mRNA were gradually gathered to one side where the flagella formed. Immunofluorescence (IF) showed that KIF3A, tubulin, and mitochondria were co-localized in different stages during spermiogenesis in B. pectinirostris. The temporal and spatial expression dynamics of KIF3A/3B indicate that KIF3A and KIF3B might be involved in flagellar assembly and maintenance at the mRNA and protein levels. Moreover, these proteins may transport the mitochondria resulting in flagellum formation in B. pectinirostris.
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Affiliation(s)
- Yong-Qiang Zhao
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China
| | - Dan-Li Mu
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China
| | - Di Wang
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China
| | - Ying-Li Han
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China
| | - Cong-Cong Hou
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China.
| | - Jun-Quan Zhu
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, People's Republic of China.
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5
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Intraflagellar transport velocity is governed by the number of active KIF17 and KIF3AB motors and their motility properties under load. Proc Natl Acad Sci U S A 2017; 114:E6830-E6838. [PMID: 28761002 DOI: 10.1073/pnas.1708157114] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Homodimeric KIF17 and heterotrimeric KIF3AB are processive, kinesin-2 family motors that act jointly to carry out anterograde intraflagellar transport (IFT), ferrying cargo along microtubules (MTs) toward the tips of cilia. How IFT trains attain speeds that exceed the unloaded rate of the slower, KIF3AB motor remains unknown. By characterizing the motility properties of kinesin-2 motors as a function of load we find that the increase in KIF3AB velocity, elicited by forward loads from KIF17 motors, cannot alone account for the speed of IFT trains in vivo. Instead, higher IFT velocities arise from an increased likelihood that KIF3AB motors dissociate from the MT, resulting in transport by KIF17 motors alone, unencumbered by opposition from KIF3AB. The rate of transport is therefore set by an equilibrium between a faster state, where only KIF17 motors move the train, and a slower state, where at least one KIF3AB motor on the train remains active in transport. The more frequently the faster state is accessed, the higher the overall velocity of the IFT train. We conclude that IFT velocity is governed by (i) the absolute numbers of each motor type on a given train, (ii) how prone KIF3AB is to dissociation from MTs relative to KIF17, and (iii) how prone both motors are to dissociation relative to binding MTs.
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6
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Zhao YQ, Yang HY, Zhang DD, Han YL, Hou CC, Zhu JQ. Dynamic transcription and expression patterns of KIF3A and KIF3B genes during spermiogenesis in the shrimp, Palaemon carincauda. Anim Reprod Sci 2017; 184:59-77. [PMID: 28689636 DOI: 10.1016/j.anireprosci.2017.06.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 05/29/2017] [Accepted: 06/22/2017] [Indexed: 01/20/2023]
Abstract
Spermiogenesis is a highly ordered and complex process in the male germ cell differentiation. The microtubule-based motor proteins KIF3A and KIF3B are required for the progression of the stages of spermiogenesis. In this study, the main goal was to determine whether KIF3A and KIF3B have a key role in spermiogenesis in Palaemon carincauda. The complete cDNA of KIF3A/3B from the testis of P. carincauda was cloned by using PCR and rapid amplification of cDNA ends (RACE). The predicted secondary and tertiary structures of KIF3A/3B contained three domains which were the: a) head region, b) stalk region, and c) tail region. Real-time quantitative PCR (qPCR) results revealed that KIF3A and KIF3B mRNAs were obtained for all the tissues examined, with the greatest gene expression in the testis. In situ hybridization indicated the KIF3A and KIF3B mRNAs were distributed in the periphery of the nuclear in the early spermatid of spermiogenesis. In the middle and late spermatid stages, KIF3A and KIF3B mRNAs were gradually upregulated and assembled to one side where acrosome biogenesis begins. In the mature sperm, KIF3A and KIF3B mRNAs were distributed in the acrosome cap and spike. Immunofluorescence studies indicated that KIF3A, tubulin, mitochondria, and Golgi were co-localized in different stages during spermiogenesis in P. carincauda. The temporal and spatial gene expression dynamics of KIF3A/3B indicate that KIF3A and KIF3B proteins may be involved in acrosome formation and nucleus shaping. Moreover, these proteins can transport the mitochondria and Golgi that facilitate acrosome formation in P. carincauda.
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Affiliation(s)
- Yong-Qiang Zhao
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China
| | - Hai-Yan Yang
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China
| | - Dan-Dan Zhang
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China
| | - Ying-Li Han
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China
| | - Cong-Cong Hou
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China
| | - Jun-Quan Zhu
- Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, Zhejiang 315211, People's Republic of China.
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7
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Scholey JM. Kinesin-2: a family of heterotrimeric and homodimeric motors with diverse intracellular transport functions. Annu Rev Cell Dev Biol 2013; 29:443-69. [PMID: 23750925 DOI: 10.1146/annurev-cellbio-101512-122335] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Kinesin-2 was first purified as a heterotrimeric, anterograde, microtubule-based motor consisting of two distinct kinesin-related subunits and a novel associated protein (KAP) that is currently best known for its role in intraflagellar transport and ciliogenesis. Subsequent work, however, has revealed diversity in the oligomeric state of different kinesin-2 motors owing to the combinatorial heterodimerization of its subunits and the coexistence of both heterotrimeric and homodimeric kinesin-2 motors in some cells. Although the functional significance of the homo- versus heteromeric organization of kinesin-2 motor subunits and the role of KAP remain uncertain, functional studies suggest that cooperation between different types of kinesin-2 motors or between kinesin-2 and a member of a different motor family can generate diverse patterns of anterograde intracellular transport. Moreover, despite being restricted to ciliated eukaryotes, kinesin-2 motors are now known to drive diverse transport events outside cilia. Here, I review the organization, assembly, phylogeny, biological functions, and motility mechanism of this diverse family of intracellular transport motors.
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Affiliation(s)
- Jonathan M Scholey
- Department of Molecular and Cell Biology, University of California, Davis, California 95616;
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8
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Dang R, Zhu JQ, Tan FQ, Wang W, Zhou H, Yang WX. Molecular characterization of a KIF3B-like kinesin gene in the testis of Octopus tankahkeei (Cephalopoda, Octopus). Mol Biol Rep 2011; 39:5589-98. [PMID: 22183304 DOI: 10.1007/s11033-011-1363-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Accepted: 12/12/2011] [Indexed: 01/03/2023]
Abstract
KIF3B is known for maintaining and assembling cilia and flagellum. To date, the function of KIF3B and its relationship with KIF3A during spermiogenesis in the cephalopod Octopus tankahkeei remains unknown. In the present study, we characterized a gene encoding a homologue of rat KIF3B in the O. tankahkeei testis and examined its temporal and spatial expression pattern during spermiogenesis. The cDNA of KIF3B was obtained with degenerate and RACE PCR and the distribution pattern of ot-kif3b were observed with RT-PCR. The morphological development during spermiogenesis was illustrated by histological and transmission electron microscopy and mRNA expression of ot-kif3b was observed by in situ hybridization. The 2,365 nucleotides cDNA consisted of a 102 bp 5' untranslated region (UTR), a 2,208 bp open reading frame (ORF) encoding a protein of 736 amino acids, and a 55 bp 3' UTR. Multiple alignments revealed that the putative Ot-KIF3B shared 68, 68, 69, 68, and 67% identity with that of Homo sapiens, Mus musculus, Gallus gallus, Danio rerio, and Xenopus laevis, respectively, along with high identities with Ot-KIF3A in fundamental structures. Ot-kif3b transcripts appeared gradually in early spermatids, increased in intermediate spermatids and maximized in drastically remodeled and final spermatids. The kif3b gene is identified and its expression pattern is demonstrated for the first time in O. tankahkeei. Compared to ot-kif3a reported by our laboratory before, our data suggested that the putative heterodimeric motor proteins Ot-KIF3A/B may be involved in intraspermatic transport and might contribute to structural changes during spermiogenesis.
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Affiliation(s)
- Ran Dang
- Faculty of Life Science and Bioengineering, Ningbo University, 315211, Zhejiang, People's Republic of China
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9
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Abstract
Long-distance transport in eukaryotic cells is driven by molecular motors that move along microtubule tracks. Molecular motors of the kinesin superfamily contain a kinesin motor domain attached to family-specific sequences for cargo binding, regulation, and oligomerization. The biochemical and biophysical properties of the kinesin motor domain have been widely studied, yet little is known about how kinesin motors work in the complex cellular environment. We discuss recent studies on the three major families involved in intracellular transport (kinesin-1, kinesin-2, and kinesin-3) that have begun to bridge the gap in knowledge between the in vitro and in vivo behaviors of kinesin motors. These studies have increased our understanding of how kinesin subunits assemble to produce a functional motor, how kinesin motors are affected by biochemical cues and obstacles present on cellular microtubules, and how multiple motors on a cargo surface can work collectively for increased force production and travel distance.
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Affiliation(s)
- Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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10
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Molecular characterization of a KIF3A-like kinesin gene in the testis of the Chinese fire-bellied newt Cynops orientalis. Mol Biol Rep 2011; 39:4207-14. [PMID: 21773941 DOI: 10.1007/s11033-011-1206-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 07/11/2011] [Indexed: 10/18/2022]
Abstract
KIF3A, the subunit within the kinesin-2 superfamily, is a typically N-terminal motor protein, which is involved in membranous organelle and intraflagellar transport. During spermatogenesis, KIF3A plays a critical role in the formation of flagella and cilia. KIF3A is also related to the left-right asymmetry, the signal pathway, DNA damage and tumorigenesis. We used RT-PCR and in situ hybridization to clone the kif3a gene, and we identified its function in the testis of the Chinese fire-bellied newt Cynops orientalis (termed as co-kif3a). The full-length sequence of co-kif3a was 2193 bp, containing a 56 bp 5'UTR, 2073 bp ORF encoding a protein of 691 amino acids and a 64 bp 3'UTR. The secondary structure analysis showed that co-KIF3A had three motor domains, representing the N-terminal motor domain (1-400 aa), α-helix domain (400-600 aa) and C-terminal tail domain (600-691 aa). The amino acid sequence of co-KIF3A shared an identity of 55.9%, 90.9%, 89.9%, 91.3% and 85.7% with its counterparts in Aedes aegypti, Mus musculus, Xenopus tropicalis, Homo sapiens and Danio rerio, respectively. The calculated molecular weight of the putative co-KIF3A was 79 kDa and its estimated isoelectric point was 6.8. RT-PCR result showed that co-kif3a was expressed in several examined tissues, with a high level in the testis and low levels in liver, muscle and ovum. Kif3a was weakly expressed in the heart and spleen, and barely detected in the intestine. In situ hybridization analysis demonstrated that in early spermatid co-kif3a was expressed around the nuclear membrane. When the tail began to emerge in the middle spermatid, mRNA transcript was abundantly concentrated in the flagellum. The mRNA signal was still very strong along all the flagellum in late spermatid. In mature spermatid, the message was weak. Therefore, co-KIF3A probably plays a functional role in the spermiogenesis of C. orientalis.
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Doodhi H, Ghosal D, Krishnamurthy M, Jana SC, Shamala D, Bhaduri A, Sowdhamini R, Ray K. KAP, the accessory subunit of kinesin-2, binds the predicted coiled-coil stalk of the motor subunits. Biochemistry 2009; 48:2248-60. [PMID: 19161286 DOI: 10.1021/bi8018338] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Kinesin-2 is an anterograde motor involved in intraflagellar transport and certain other intracellular transport processes. It consists of two different motor subunits and an accessory protein KAP (kinesin accessory protein). The motor subunits were shown to bind each other through the coiled-coil stalk domains, while KAP was proposed to bind the tail domains of the motor subunits. Although several genetic studies established that KAP plays an important role in kinesin-2 functions, its exact role remains unclear. Here, we report the results of a systematic analysis of the KAP binding sites by using recombinant Drosophila kinesin-2 subunits as well as the endogenous proteins. These show that at least one of the coiled-coil stalks is sufficient to bind the N-terminal region of DmKAP. The soluble complex involving the recombinant kinesin-2 fragments is reconstituted in vitro at high salt concentrations, suggesting that the interaction is primarily nonionic. Furthermore, independent distant homology modeling indicated that DmKAP may bind along the coiled-coil stalks through a combination of predominantly hydrophobic interactions and hydrogen bonds. These observations led us to propose that KAP would stabilize the motor subunit heterodimer and help assemble a greater kinesin-2 complex in vivo.
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Affiliation(s)
- Harinath Doodhi
- Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India
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12
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The reciprocal coordination and mechanics of molecular motors in living cells. Proc Natl Acad Sci U S A 2009; 106:3190-5. [PMID: 19221028 DOI: 10.1073/pnas.0809849106] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Molecular motors in living cells are involved in whole-cell locomotion, contractility, developmental shape changes, and organelle movement and positioning. Whether motors of different directionality are functionally coordinated in cells or operate in a semirandom "tug of war" is unclear. We show here that anterograde and retrograde microtubule-based motors in the flagella of Chlamydomonas are regulated such that only motors of a common directionality are engaged at any single time. A laser trap was used to position microspheres on the plasma membrane of immobilized paralyzed Chlamydomonas flagella. The anterograde and retrograde movements of the microsphere were measured with nanometer resolution as microtubule-based motors engaged the transmembrane protein FMG-1. An average of 10 motors acted to move the microsphere in either direction. Reversal of direction during a transport event was uncommon, and quiescent periods separated every transport event, suggesting the coordinated and exclusive action of only a single motor type. After a jump to 32 degrees C, temperature-sensitive mutants of kinesin-2 (fla10) showed exclusively retrograde transport events, driven by 7 motors on average. These data suggest that molecular motors in living cells can be reciprocally coordinated to engage simultaneously in large numbers and for exclusive transport in a single direction, even when a mixed population of motors is present. This offers a unique model for studying the mechanics, regulation, and directional coordination of molecular motors in a living intracellular environment.
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13
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Gu C, Zhou W, Puthenveedu MA, Xu M, Jan YN, Jan LY. The Microtubule Plus-End Tracking Protein EB1 Is Required for Kv1 Voltage-Gated K+ Channel Axonal Targeting. Neuron 2006; 52:803-16. [PMID: 17145502 DOI: 10.1016/j.neuron.2006.10.022] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2005] [Revised: 12/29/2005] [Accepted: 10/20/2006] [Indexed: 01/25/2023]
Abstract
Axonal Kv1 channels regulate action potential propagation-an evolutionarily conserved function important for the control of motor behavior as evidenced from the linkage of human Kv1 channel mutations to myokymia/episodic ataxia type 1 (EA1) and the Shaker mutant phenotype in Drosophila. To search for the machinery that mediates axonal targeting of Kv1 channels composed of both alpha and beta subunits, we first demonstrate that Kvbeta2 is responsible for targeting Kv1 channels to the axon. Next, we show that Kvbeta2 axonal targeting depends on its ability to associate with the microtubule (MT) plus-end tracking protein (+TIP) EB1. Not only do Kvbeta2 and EB1 move in unison down the axon, Brefeldin A-sensitive Kv1-containing vesicles can also be found at microtubule ends near the cell membrane. In addition, we found that Kvbeta2 associates with KIF3/kinesin II as well. Indeed, Kv1 channels rely on both KIF3/kinesin II and EB1 for their axonal targeting.
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Affiliation(s)
- Chen Gu
- Howard Hughes Medical Institute, Departments of Physiology and Biochemistry, University of California, San Francisco, San Francisco, California 94143, USA.
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14
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Abstract
Kinesin-2 is a major microtubule-based motor in most cell types. Its in vitro motile properties have been analyzed extensively and been found to differ considerably from kinesin-1. Although recombinant kinesin-2 heterodimers exhibit processive movement, the processivity of the native kinesin-2 holoenzyme has never been evaluated. Kinesin-2 can interact with dynactin, a 'processivity factor' for cytoplasmic dynein, which may alter its motile properties. In this study, we analyze the in vitro motility of single native kinesin-2 molecules and determine the effects of dynactin on motor processivity. We find that individual native kinesin-2 molecules travel processively. Dynactin has no effect on velocity but significantly increases the run length of kinesin-2 movements. These results show that the interaction with dynactin has important functional consequences on the activity of the kinesin-2 motor.
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Affiliation(s)
- Matthew A Berezuk
- Department of Biology, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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Pan X, Ou G, Civelekoglu-Scholey G, Blacque OE, Endres NF, Tao L, Mogilner A, Leroux MR, Vale RD, Scholey JM. Mechanism of transport of IFT particles in C. elegans cilia by the concerted action of kinesin-II and OSM-3 motors. ACTA ACUST UNITED AC 2006; 174:1035-45. [PMID: 17000880 PMCID: PMC2064394 DOI: 10.1083/jcb.200606003] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The assembly and function of cilia on Caenorhabditis elegans neurons depends on the action of two kinesin-2 motors, heterotrimeric kinesin-II and homodimeric OSM-3–kinesin, which cooperate to move the same intraflagellar transport (IFT) particles along microtubule (MT) doublets. Using competitive in vitro MT gliding assays, we show that purified kinesin-II and OSM-3 cooperate to generate movement similar to that seen along the cilium in the absence of any additional regulatory factors. Quantitative modeling suggests that this could reflect an alternating action mechanism, in which the motors take turns to move along MTs, or a mechanical competition, in which the motors function in a concerted fashion to move along MTs with the slow motor exerting drag on the fast motor and vice versa. In vivo transport assays performed in Bardet-Biedl syndrome (BBS) protein and IFT motor mutants favor a mechanical competition model for motor coordination in which the IFT motors exert a BBS protein–dependent tension on IFT particles, which controls the IFT pathway that builds the cilium foundation.
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Affiliation(s)
- Xiaoyu Pan
- Section of Molecular and Cellular Biology, Center for Genetics and Development, University of California, Davis, Davis, CA 95616, USA
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Imai H, Narita A, Schroer TA, Maéda Y. Two-dimensional averaged images of the dynactin complex revealed by single particle analysis. J Mol Biol 2006; 359:833-9. [PMID: 16697405 DOI: 10.1016/j.jmb.2006.03.071] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2006] [Revised: 03/28/2006] [Accepted: 03/31/2006] [Indexed: 11/20/2022]
Abstract
The dynactin complex interacts with dynein and numerous other proteins to provide for a wide range of subcellular transport functions. A detailed understanding of the structure and subunit organization of dynactin should yield new insights into its function. In the present study, we used single particle analysis to obtain a two-dimensional averaged image of dynactin isolated from chick embryo brains and visualized by negative stain electron microscopy (EM). Each individual image, consisting of the shoulder/sidearm and the rod, closely resembled the previously published quick-freeze deep-etch rotary-shadow electron micrographs. However, the averaged image revealed novel structural features that may have functional significance. The bulky shoulder complex has a triangular shape and is 13 nm wide and 8 nm high. The rod, with an overall length of 40 nm, consists of clearly defined lobes that are apparently grouped into three parts, the pointed-end complex, the middle segment, and the extra lobes at the barbed end. The pointed-end complex reveals the characteristic protrusions and clefts that were previously observed only in the isolated pointed-end complex. In the middle segment, the seven lobes are fitted to the helical symmetry of F-actin. A narrow but prominent gap separates the previously unidentified extra three lobes at the barbed end from the middle segment. The averaged image we obtained contrasts dramatically with the simple Arp1 polymer that was previously reported by single particle analysis of bovine brain dynactin. These apparent structural differences are probably due to the greater stability and integrity of the chick embryo brain dynactin preparation. We propose a new structural model for dynactin, based on our observations.
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Affiliation(s)
- Hiroshi Imai
- ERATO Actin Filament Dynamics Project, Japan Science and Technology Agency c/o RIKEN, Sayo, Hyogo 679-5148, Japan
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Abstract
Cargoes are transported intracellularly along cytoskeletal tracks composed of actin or tubulin. Their movement involves the action of molecular motor proteins that generate directed movement along microtubules or actin filaments. The three classes of molecular motors--kinesins, dyneins and myosins--are involved in a multiplicity of biological movements such as mitosis, positioning of organelles, intracellular transports and also vesicular sorting through membrane tubulation and fission and delivery to their target compartment. Intracellular pathogens use this molecular machinery to reach their site of replication, to leave their host or to control the dynamics of membrane exchanges with their replication compartment.
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Affiliation(s)
- Thomas Henry
- Centre d'Immunologie de Marseille-Luminy, CNRS-INSERM-Université Méditerranée, Parc Scientifique de Luminy, Case 906-13288 Marseille Cedex 9, France
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