A Novel Tctex2-related Light Chain Is Required for Stability of Inner Dynein Arm I1 and Motor Function in the Chlamydomonas Flagellum

DiBella, Linda M.; Smith, Elizabeth F.; Patel‐King, Ramila S.; Wakabayashi, K.; King, Stephen M.

doi:10.1074/jbc.m313540200

Cited by 45 publications

(54 citation statements)

References 60 publications

(79 reference statements)

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“…Key conclusions from this study include that IC138 is a WD-repeat protein and that in vivo the WD-repeat structure is important for assembly of the roadblock-like light chain, LC7b, a newly identified component of the I1 complex (DiBella et al, 2004b). The basis for these conclusions is that the IC138 gene rescues the bop5-1 motility defects; that the bop5-1 allele contains a mutation that results in the deletion of the seventh WD-repeat of IC138; and although the truncated IC138 and the other I1 proteins assemble in bop5-1 axonemes, LC7b fails to assemble in the complex.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the truncated IC138 assembles in axonemes from bop5-1, and based on a combination of Western blots and protein stains, most of the other known I1 subunits also assemble and can be salt extracted as a relatively stable and intact 18S I1 complex (see Results). The one exception is that LC7b (DiBella et al, 2004b) fails to assemble in the I1 complex in bop5-1 axonemes, suggesting that IC138 plays a role in anchoring this dynein light chain.The failure of LC7b assembly in the I1 complex of bop5-1 axonemes is one of the most revealing outcomes of this study. LC7b is a newly identified member of the roadblock class of dynein light chains (DiBella et al, 2004b).…”

mentioning

confidence: 99%

“…The one exception is that LC7b (DiBella et al, 2004b) fails to assemble in the I1 complex in bop5-1 axonemes, suggesting that IC138 plays a role in anchoring this dynein light chain.…”

mentioning

confidence: 99%

“…Furthermore, based on silver stained gels, bop5-1 axonemes also contain 1␤ Dhc (our unpublished data) and IC97 ( Figure 6B). The dynein light chains LC7a and LC7b are located in the outer dynein arm as well as the inner dynein arm I1 complex (Piperno and Luck, 1979;Pfister et al, 1982;Harrison et al, 1998;DiBella et al, 2004b). Therefore, to determine whether LC7a and LC7b are present in the I1 complex it was necessary to perform the Western blot on axonemes from the double mutant bop5-1oda7, which contains the truncated IC138 and is missing the outer arm dynein.…”

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confidence: 99%

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IC138 Is a WD-Repeat Dynein Intermediate Chain Required for Light Chain Assembly and Regulation of Flagellar Bending

Hendrickson

Perrone

Griffin

et al. 2004

MBoC

147

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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. INTRODUCTIONOur goal is to determine the mechanisms that regulate ciliary and eukaryotic flagellar bending. Based on informative mutations in Chlamydomonas, and effective in vitro functional studies, a surprisingly complex array of different dynein motors is required for generation and control of normal ciliary and flagellar bending (Mitchell, 1994;Gibbons, 1995;Porter, 1996;Porter and Sale, 2000;DiBella and King, 2001;Kamiya, 2002). For example, the outer arm dyneins are homogeneous structures responsible for control of beat frequency and power required for movement (Satir et al., 1993;Brokaw, 1994;DiBella and King, 2001;Kamiya, 2002). The inner arm dyneins, however, are more complex, composed of at least seven different dynein subspecies precisely organized in a 96-nm repeat pattern along each doublet microtubule of the axoneme (Porter, 1996;Porter and Sale, 2000). Diverse data indicate the inner arm dyneins control the size and shape of the flagellar bend (Brokaw and Kamiya, 1987;Brokaw, 1994;Kamiya, 2002). The mechanism for control of flagellar waveform involves additional structures (e.g., radial spokes, central pair apparatus, and the dynein regulatory complex) and control of dynein phosphorylation (Porter and Sale, 2000;DiBella and King, 2001;Kamiya, 2002;Smith and Yang, 2004).The present study is focused on a single inner arm dynein, the I1 complex, also called the f-dynein (Goodenough et al., 1987;Piperno et al., 1990;Kagami and Kamiya, 1992;Porter et al., 1992). The I1 complex is a tripartite structure, or triad, located near the base of the S1 radial spoke, at the proximal end of the axonemal 96-nm repeat (Goodenough and Heuser, 1985;Piperno et al., 1990;Mastronar...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

“…The one exception is that LC7b (DiBella et al, 2004b) fails to assemble in the I1 complex in bop5-1 axonemes, suggesting that IC138 plays a role in anchoring this dynein light chain.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

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IC138 Is a WD-Repeat Dynein Intermediate Chain Required for Light Chain Assembly and Regulation of Flagellar Bending

Hendrickson

Perrone

Griffin

et al. 2004

MBoC

147

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“…In cytoplasm, Tctex1 interacts with a variety of proteins in addition to dynein (e.g., Doc-2 [Nagano et al, 1998], rhodopThis article was published online ahead of print in MBC in Press (http://www.molbiolcell.org/cgi/doi/10.1091/mbc.E05-08 -0732) on September 29, 2005. sin [Tai et al, 1999], polio virus receptor [Mueller et al, 2002], mitochondrial voltage-dependent anion channel [Schwarzer et al, 2002], neuronal voltage-gated Ca 2ϩ channels [Lai et al, 2005], Fyn kinase [Kai et al, 1997;Mou et al, 1998], and the Herpes capsid protein VP26 [Douglas et al, 2004]) and has been proposed to act as an adaptor to attach specific cargoes to this motor (Tai et al, 1999). In Chlamydomonas, one Tctex2 homologue (termed LC2) is required for assembly of functional outer arms (Patel-King et al, 1997;Pazour et al, 1999), whereas a related protein imparts stability to inner arm I1 and is necessary for wild-type motor activity (DiBella et al, 2004b). Intriguingly, Tctex1 null alleles in Drosophila are viable, although these mutants are male sterile.…”

Section: Introductionmentioning

confidence: 99%

Differential Light Chain Assembly Influences Outer Arm Dynein Motor Function

DiBella

Gorbatyuk

Sakato

et al. 2005

MBoC

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Tctex1 and Tctex2 were originally described as potential distorters/sterility factors in the non-Mendelian transmission of t-haplotypes in mice. These proteins have since been identified as subunits of cytoplasmic and/or axonemal dyneins. Within the Chlamydomonas flagellum, Tctex1 is a subunit of inner arm I1. We have now identified a second Tctex1-related protein (here termed LC9) in Chlamydomonas. LC9 copurifies with outer arm dynein in sucrose density gradients and is missing only in those strains completely lacking this motor. Zero-length cross-linking of purified outer arm dynein indicates that LC9 interacts directly with both the IC1 and IC2 intermediate chains. Immunoblot analysis revealed that LC2, LC6, and LC9 are missing in an IC2 mutant strain (oda6-r88) that can assemble outer arms but exhibits significantly reduced flagellar beat frequency. This defect is unlikely to be due to lack of LC6, because an LC6 null mutant (oda13) exhibits only a minor swimming abnormality. Using an LC2 null mutant (oda12-1), we find that although some outer arm dynein components assemble in the absence of LC2, they are nonfunctional. In contrast, dyneins from oda6-r88, which also lack LC2, retain some activity. Furthermore, we observed a synthetic assembly defect in an oda6-r88 oda12-1 double mutant. These data suggest that LC2, LC6, and LC9 have different roles in outer arm assembly and are required for wild-type motor function in the Chlamydomonas flagellum.

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Dynein light chain family in Tetrahymena thermophila

Wilkes

Rajagopalan

Chan

et al. 2006

Cell Motil. Cytoskeleton

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Dyneins are large protein complexes that produce directed movement on microtubules. In situ, dyneins comprise combinations of heavy, intermediate, light-intermediate, and light chains. The light chains regulate the locations and activities of dyneins but their functions are not completely understood. We have searched the recently sequenced Tetrahymena thermophila macronuclear genome to describe the entire family of dynein light chains expressed in this organism. We identified fourteen genes encoding putative dynein light chains and seven genes encoding light chain-like proteins. RNA-directed PCR revealed that all 21 genes were expressed. Quantitative real time reverse transcription PCR showed that many of these genes were upregulated after deciliation, indicating that these proteins are present in cilia. Using the nomenclature developed in Chlamydomonas, Tetrahymena expresses two isoforms each of LC2, LC4, LC7, and Tctex1, three isoforms of p28, and six LC8/LC8-like isoforms. Tetrahymena also expresses two LC3-like genes. No Tetrahymena orthologue was found for Chlamydomonas LC5 or LC6. This study provides a complete description of the different genes and isoforms of the dynein light chains that are expressed in Tetrahymena, a model organism in which the targeted manipulation of genes is straightforward.

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A Novel Tctex2-related Light Chain Is Required for Stability of Inner Dynein Arm I1 and Motor Function in the Chlamydomonas Flagellum

Cited by 45 publications

References 60 publications

IC138 Is a WD-Repeat Dynein Intermediate Chain Required for Light Chain Assembly and Regulation of Flagellar Bending

IC138 Is a WD-Repeat Dynein Intermediate Chain Required for Light Chain Assembly and Regulation of Flagellar Bending

Differential Light Chain Assembly Influences Outer Arm Dynein Motor Function

Dynein light chain family in Tetrahymena thermophila

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