The sup-pf-2 mutations of Chlamydomonas alter the activity of the outer dynein arms by modification of the gamma-dynein heavy chain.

Rupp, Gerald; O’Toole, Eileen; Gardner, Lynne C.; Mitchell, Beth F.; Porter, Mary E.

doi:10.1083/jcb.135.6.1853

Cited by 80 publications

(65 citation statements)

References 62 publications

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“…As discussed above, Chlamydomonas pf mutants, which lack the spokes and/or CP, are motile if they also carry a suppressor mutation (Brokaw et al, 1982;Huang et al, 1982;Porter et al, 1992). Some of the suppressor mutations lead to defects in the regulatory chains of both inner and outer dyneins (Porter et al, 1992;Porter et al, 1994;Rupp et al, 1996). Other mutations cause the absence of regulatory proteins and/or dynein subsets (Piperno et al, 1994;Piperno, 1995;Rupp et al, 1996).…”

Section: Dynein I1 and The Role Of The Cp-spoke Axismentioning

confidence: 99%

Flagellar and ciliary beating: the proven and the possible

Lindemann

Lesich

2010

Journal of Cell Science

258

215

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SummaryThe working mechanism of the eukaryotic flagellar axoneme remains one of nature's most enduring puzzles. The basic mechanical operation of the axoneme is now a story that is fairly complete; however, the mechanism for coordinating the action of the dynein motor proteins to produce beating is still controversial. Although a full grasp of the dynein switching mechanism remains elusive, recent experimental reports provide new insights that might finally disclose the secrets of the beating mechanism: the special role of the inner dynein arms, especially dynein I1 and the dynein regulatory complex, the importance of the dynein microtubule-binding affinity at the stalk, and the role of bending in the selection of the active dynein group have all been implicated by major new evidence. This Commentary considers this new evidence in the context of various hypotheses of how axonemal dynein coordination might work.

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Section: Dynein I1 and The Role Of The Cp-spoke Axismentioning

confidence: 99%

Flagellar and ciliary beating: the proven and the possible

Lindemann

Lesich

2010

Journal of Cell Science

258

215

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“…Additional support is provided by the analysis of suppressor mutations that restore motility to both radial spoke and central apparatus defective mutants without restoring the missing structures (49). These mutations occur in genes encoding heavy chains of outer dynein arms (49)(50)(51). One mutation, sup-pf-2, is in the gene encoding the ␥ heavy chain subunit (51) and results in the asymmetric assembly of the outer dynein arms on subsets of doublet microtubules.…”

Section: In High Calcium the Central Apparatus Is Randomly Oriented Inmentioning

confidence: 99%

“…These mutations occur in genes encoding heavy chains of outer dynein arms (49)(50)(51). One mutation, sup-pf-2, is in the gene encoding the ␥ heavy chain subunit (51) and results in the asymmetric assembly of the outer dynein arms on subsets of doublet microtubules. Although the sup-pf-2 mutation restores motility to mutants lacking the radial spokes or central apparatus, flagella of these double mutants beat with a predominantly symmetric waveform (49,52,53).…”

Section: In High Calcium the Central Apparatus Is Randomly Oriented Inmentioning

confidence: 99%

Asymmetry of the central apparatus defines the location of active microtubule sliding in Chlamydomonas flagella

Wargo

Smith

2002

Proc. Natl. Acad. Sci. U.S.A.

114

118

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Regulation of ciliary and flagellar motility requires spatial control of dynein-driven microtubule sliding. However, the mechanism for regulating the location and symmetry of dynein activity is not understood. One hypothesis is that the asymmetrically organized central apparatus, through interactions with the radial spokes, transmits a signal to regulate dynein-driven microtubule sliding between subsets of doublet microtubules. Based on this model, we hypothesized that the orientation of the central apparatus defines positions of active microtubule sliding required to control bending in the axoneme. To test this, we induced microtubule sliding in axonemes isolated from wild-type and mutant Chlamydomonas cells, and then used electron microscopy to determine the orientation of the central apparatus. Transverse sections of wild-type axonemes revealed that the C1 microtubule is predominantly oriented toward the position of active microtubule sliding. In contrast, the central apparatus is randomly oriented in axonemes isolated from radial spoke deficient mutants. For outer arm dynein mutants, the C1 microtubule is oriented toward the position of active microtubule sliding in low calcium buffer, but is randomly oriented in high calcium buffer. These results provide evidence that the central apparatus defines the position of active microtubule sliding, and may regulate the size and shape of axonemal bends through interactions with the radial spokes. In addition, our results indicate that in high calcium conditions required to generate symmetric waveforms, the outer dynein arms are potential targets of the central pair-radial spoke control system.

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“…The bypass mutations are thought to identify components in the signal transduction pathway between the central pair/ radial spoke structures and the dynein arms. Characterization of the bypass mutations has identified defects in genes encoding components of the outer dynein arms (Huang et al, 1982;Porter et al, 1994;Rupp et al, 1996), the inner dynein arms Myster et al, 1997), and the dynein regulatory complex (Huang et al, 1982;Piperno et al, 1992). These and other studies suggest that the central pair microtubules regulate dynein arm activity through a signal transduction cascade that involves the radial spokes and the dynein regulatory complex.…”

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confidence: 91%

“…Complementation tests were performed by constructing stable diploid cell lines using the complementing arg2 and arg7 markers (Ebersold, 1967). Assessment of motility phenotypes and measurements of swimming velocity were performed as previously described (Rupp et al, 1996). …”

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confidence: 99%

TheChlamydomonas PF6Locus Encodes a Large Alanine/Proline-Rich Polypeptide That Is Required for Assembly of a Central Pair Projection and Regulates Flagellar Motility

Rupp

O’Toole

Porter

2001

MBoC

113

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Efficient motility of the eukaryotic flagellum requires precise temporal and spatial control of its constituent dynein motors. The central pair and its associated structures have been implicated as important members of a signal transduction cascade that ultimately regulates dynein arm activity. To identify central pair components involved in this process, we characterized a Chlamydomonas motility mutant (pf6-2) obtained by insertional mutagenesis. pf6-2 flagella twitch ineffectively and lack the 1a projection on the C1 microtubule of the central pair. Transformation with constructs containing a full-length, wild-type copy of the PF6 gene rescues the functional, structural, and biochemical defects associated with the pf6 mutation. Sequence analysis indicates that the PF6 gene encodes a large polypeptide that contains numerous alanine-rich, proline-rich, and basic domains and has limited homology to an expressed sequence tag derived from a human testis cDNA library. Biochemical analysis of an epitope-tagged PF6 construct demonstrates that the PF6 polypeptide is an axonemal component that cosediments at 12.6S with several other polypeptides. The PF6 protein appears to be an essential component required for assembly of some of these polypeptides into the C1-1a projection. INTRODUCTIONCilia and flagella are highly conserved structures found on diverse cell types, ranging from single-cell protozoa to multicellular tissues in humans, where they function to propel cells through a fluid environment or to transport fluid across a cell surface. Motile cilia are also found in the embryonic node (Sulik et al., 1994; Bellomo et al., 1996), where their motility appears to be critical for establishing the morphogenetic gradient that determines the left-right body axis in mammals (Nonaka et al., 1998). Defects in the assembly or activity of cilia and flagella result in a variety of abnormalities, including defects in left-right axis asymmetry, infertility, and respiratory disease (Afzelius et al., 1975; Afzelius, 1995;Supp et al., 1999). Most motile cilia and flagella contain an axoneme that consists of nine outer doublet microtubules surrounding two central singlet microtubules. The outer doublets contain binding sites for the inner and outer dynein arms, the molecular motors that power axoneme motility (reviewed by Porter, 1996;King, 2000). The dynein arms on one outer doublet interact transiently with the adjacent doublet to generate the force for interdoublet microtubule sliding. Other structures within the axoneme constrain and coordinate the activity of the multiple dynein motors and thereby convert microtubule sliding into flagellar bending.Both structural and genetic evidence indicate that the central pair microtubules and radial spokes play an important role in coordinating dynein activity. The two central pair microtubules are structurally asymmetric, and in several organisms, this apparatus has been shown to undergo clockwise rotation at a rate of approximately one turn per beat (reviewed by Omoto et al., 1999). Thes...

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The sup-pf-2 mutations of Chlamydomonas alter the activity of the outer dynein arms by modification of the gamma-dynein heavy chain.

Cited by 80 publications

References 62 publications

Flagellar and ciliary beating: the proven and the possible

Flagellar and ciliary beating: the proven and the possible

Asymmetry of the central apparatus defines the location of active microtubule sliding in Chlamydomonas flagella

TheChlamydomonas PF6Locus Encodes a Large Alanine/Proline-Rich Polypeptide That Is Required for Assembly of a Central Pair Projection and Regulates Flagellar Motility

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