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Axonemal radial spokes: 3D structure, function and assembly.

Pigino G, Ishikawa T - Bioarchitecture (2012)

Bottom Line: Despite numerous biochemical, physiological and structural studies, the mechanism of the function of the radial spoke remains unclear.Detailed knowledge of the 3D structure of the RS protein complex is needed in order to understand how RS regulates dynein activity.Here we review the most important findings on the structure of the RS, including results of our recent cryo-electron tomographic analysis of the RS protein complex.

View Article: PubMed Central - PubMed

ABSTRACT
The radial spoke (RS) is a complex of at least 23 proteins that works as a mechanochemical transducer between the central-pair apparatus and the peripheral microtubule doublets in eukaryotic flagella and motile cilia. The RS contributes to the regulation of the activity of dynein motors, and thus to flagellar motility. Despite numerous biochemical, physiological and structural studies, the mechanism of the function of the radial spoke remains unclear. Detailed knowledge of the 3D structure of the RS protein complex is needed in order to understand how RS regulates dynein activity. Here we review the most important findings on the structure of the RS, including results of our recent cryo-electron tomographic analysis of the RS protein complex.

No MeSH data available.


Related in: MedlinePlus

Figure 2. 3D structure of WT RSs in C. reinhardtii. (A–C) Surface renderings of tomographic reconstruction after 3D subtomogram averaging. (A) Longitudinal view showing the B‐ microtubule (foreground), radial spoke 1 (RS1)(purple), radial spoke 2 (RS2)(red), the RS3 stump (RS3S)(orange) (arrow), the IDAs (blue), the intermediate and light chains of IDAs (yellow), the DRC (green). The proximal end of the axoneme points toward the left. Arrowheads indicate densities specific to RS2. The boundaries between the head, neck, stalk, and base domains are shown. (B) Side view seen from the proximal end showing RS1, IDA a or d (a/d), ODA, and the microtubule doublet. A, A‐microtubule; B, B‐microtubule. The dashed line indicates the dynein a/d tail connecting to the RS1 base. The red lines show the position of section planes through the original density map used to generate subfigures (shown in D, 3–5). (C) Top view showing the two RS heads. The proximal end points to the left as in A. The pale red area identifies one of the symmetrical subdomains composing the RS head. Two such subdomains build one RS head. The red ellipse indicates the 2-fold rotational symmetry between these subdomains. The two RS heads are also symmetrical, also following a 2-fold rotational symmetry, denoted by a blue ellipse. (D) Sections through the density map of the model shown in A–C. (1) Same orientation as in A; (2) Same orientation as in B; (3–5) Same orientation as in C. The proximal end is pointing toward the left in all sections, except for section 2, where the proximal end is oriented toward the reader. Bar, 50 nm. (Modified from ©Pigino et al., 2011. Originally published in JCB. doi: 10.1083/jcb.201106125)
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Figure 2: Figure 2. 3D structure of WT RSs in C. reinhardtii. (A–C) Surface renderings of tomographic reconstruction after 3D subtomogram averaging. (A) Longitudinal view showing the B‐ microtubule (foreground), radial spoke 1 (RS1)(purple), radial spoke 2 (RS2)(red), the RS3 stump (RS3S)(orange) (arrow), the IDAs (blue), the intermediate and light chains of IDAs (yellow), the DRC (green). The proximal end of the axoneme points toward the left. Arrowheads indicate densities specific to RS2. The boundaries between the head, neck, stalk, and base domains are shown. (B) Side view seen from the proximal end showing RS1, IDA a or d (a/d), ODA, and the microtubule doublet. A, A‐microtubule; B, B‐microtubule. The dashed line indicates the dynein a/d tail connecting to the RS1 base. The red lines show the position of section planes through the original density map used to generate subfigures (shown in D, 3–5). (C) Top view showing the two RS heads. The proximal end points to the left as in A. The pale red area identifies one of the symmetrical subdomains composing the RS head. Two such subdomains build one RS head. The red ellipse indicates the 2-fold rotational symmetry between these subdomains. The two RS heads are also symmetrical, also following a 2-fold rotational symmetry, denoted by a blue ellipse. (D) Sections through the density map of the model shown in A–C. (1) Same orientation as in A; (2) Same orientation as in B; (3–5) Same orientation as in C. The proximal end is pointing toward the left in all sections, except for section 2, where the proximal end is oriented toward the reader. Bar, 50 nm. (Modified from ©Pigino et al., 2011. Originally published in JCB. doi: 10.1083/jcb.201106125)

Mentions: Strikingly, we have also revealed that the 96 nm repeat in Chlamydomonas contains a fraction of RS3 within the doublet repeat (Figs. 2Aand3A).2 However, the functional difference between triplet and doublet repeats remains to be elucidated.


Axonemal radial spokes: 3D structure, function and assembly.

Pigino G, Ishikawa T - Bioarchitecture (2012)

Figure 2. 3D structure of WT RSs in C. reinhardtii. (A–C) Surface renderings of tomographic reconstruction after 3D subtomogram averaging. (A) Longitudinal view showing the B‐ microtubule (foreground), radial spoke 1 (RS1)(purple), radial spoke 2 (RS2)(red), the RS3 stump (RS3S)(orange) (arrow), the IDAs (blue), the intermediate and light chains of IDAs (yellow), the DRC (green). The proximal end of the axoneme points toward the left. Arrowheads indicate densities specific to RS2. The boundaries between the head, neck, stalk, and base domains are shown. (B) Side view seen from the proximal end showing RS1, IDA a or d (a/d), ODA, and the microtubule doublet. A, A‐microtubule; B, B‐microtubule. The dashed line indicates the dynein a/d tail connecting to the RS1 base. The red lines show the position of section planes through the original density map used to generate subfigures (shown in D, 3–5). (C) Top view showing the two RS heads. The proximal end points to the left as in A. The pale red area identifies one of the symmetrical subdomains composing the RS head. Two such subdomains build one RS head. The red ellipse indicates the 2-fold rotational symmetry between these subdomains. The two RS heads are also symmetrical, also following a 2-fold rotational symmetry, denoted by a blue ellipse. (D) Sections through the density map of the model shown in A–C. (1) Same orientation as in A; (2) Same orientation as in B; (3–5) Same orientation as in C. The proximal end is pointing toward the left in all sections, except for section 2, where the proximal end is oriented toward the reader. Bar, 50 nm. (Modified from ©Pigino et al., 2011. Originally published in JCB. doi: 10.1083/jcb.201106125)
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Figure 2: Figure 2. 3D structure of WT RSs in C. reinhardtii. (A–C) Surface renderings of tomographic reconstruction after 3D subtomogram averaging. (A) Longitudinal view showing the B‐ microtubule (foreground), radial spoke 1 (RS1)(purple), radial spoke 2 (RS2)(red), the RS3 stump (RS3S)(orange) (arrow), the IDAs (blue), the intermediate and light chains of IDAs (yellow), the DRC (green). The proximal end of the axoneme points toward the left. Arrowheads indicate densities specific to RS2. The boundaries between the head, neck, stalk, and base domains are shown. (B) Side view seen from the proximal end showing RS1, IDA a or d (a/d), ODA, and the microtubule doublet. A, A‐microtubule; B, B‐microtubule. The dashed line indicates the dynein a/d tail connecting to the RS1 base. The red lines show the position of section planes through the original density map used to generate subfigures (shown in D, 3–5). (C) Top view showing the two RS heads. The proximal end points to the left as in A. The pale red area identifies one of the symmetrical subdomains composing the RS head. Two such subdomains build one RS head. The red ellipse indicates the 2-fold rotational symmetry between these subdomains. The two RS heads are also symmetrical, also following a 2-fold rotational symmetry, denoted by a blue ellipse. (D) Sections through the density map of the model shown in A–C. (1) Same orientation as in A; (2) Same orientation as in B; (3–5) Same orientation as in C. The proximal end is pointing toward the left in all sections, except for section 2, where the proximal end is oriented toward the reader. Bar, 50 nm. (Modified from ©Pigino et al., 2011. Originally published in JCB. doi: 10.1083/jcb.201106125)
Mentions: Strikingly, we have also revealed that the 96 nm repeat in Chlamydomonas contains a fraction of RS3 within the doublet repeat (Figs. 2Aand3A).2 However, the functional difference between triplet and doublet repeats remains to be elucidated.

Bottom Line: Despite numerous biochemical, physiological and structural studies, the mechanism of the function of the radial spoke remains unclear.Detailed knowledge of the 3D structure of the RS protein complex is needed in order to understand how RS regulates dynein activity.Here we review the most important findings on the structure of the RS, including results of our recent cryo-electron tomographic analysis of the RS protein complex.

View Article: PubMed Central - PubMed

ABSTRACT
The radial spoke (RS) is a complex of at least 23 proteins that works as a mechanochemical transducer between the central-pair apparatus and the peripheral microtubule doublets in eukaryotic flagella and motile cilia. The RS contributes to the regulation of the activity of dynein motors, and thus to flagellar motility. Despite numerous biochemical, physiological and structural studies, the mechanism of the function of the radial spoke remains unclear. Detailed knowledge of the 3D structure of the RS protein complex is needed in order to understand how RS regulates dynein activity. Here we review the most important findings on the structure of the RS, including results of our recent cryo-electron tomographic analysis of the RS protein complex.

No MeSH data available.


Related in: MedlinePlus