Dataset Information

Axonemal dynein light chain-1 locates at the microtubule-binding domain of the ? heavy chain.

ABSTRACT: The outer arm dynein (OAD) complex is the main propulsive force generator for ciliary/flagellar beating. In Chlamydomonas and Tetrahymena, the OAD complex comprises three heavy chains (?, ?, and ? HCs) and >10 smaller subunits. Dynein light chain-1 (LC1) is an essential component of OAD. It is known to associate with the Chlamydomonas ? head domain, but its precise localization within the ? head and regulatory mechanism of the OAD complex remain unclear. Here Ni-NTA-nanogold labeling electron microscopy localized LC1 to the stalk tip of the ? head. Single-particle analysis detected an additional structure, most likely corresponding to LC1, near the microtubule-binding domain (MTBD), located at the stalk tip. Pull-down assays confirmed that LC1 bound specifically to the ? MTBD region. Together with observations that LC1 decreased the affinity of the ? MTBD for microtubules, we present a new model in which LC1 regulates OAD activity by modulating ? MTBD's affinity for the doublet microtubule.

SUBMITTER: Ichikawa M

PROVIDER: S-EPMC4642857 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Axonemal dynein light chain-1 locates at the microtubule-binding domain of the γ heavy chain.

Ichikawa Muneyoshi M Saito Kei K Yanagisawa Haru-Aki HA Yagi Toshiki T Kamiya Ritsu R Yamaguchi Shin S Yajima Junichiro J Kushida Yasuharu Y Nakano Kentaro K Numata Osamu O Toyoshima Yoko Y YY

Molecular biology of the cell 20150923 23

The outer arm dynein (OAD) complex is the main propulsive force generator for ciliary/flagellar beating. In Chlamydomonas and Tetrahymena, the OAD complex comprises three heavy chains (α, β, and γ HCs) and >10 smaller subunits. Dynein light chain-1 (LC1) is an essential component of OAD. It is known to associate with the Chlamydomonas γ head domain, but its precise localization within the γ head and regulatory mechanism of the OAD complex remain unclear. Here Ni-NTA-nanogold labeling electron mi ...[more]

PMID: 26399296

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Project description:This study compares the role of electrostatics in the binding process between microtubules and two dynein microtubule-binding domains (MTBDs): cytoplasmic and axonemal. These two dyneins are distinctively different in terms of their functionalities: cytoplasmic dynein is processive, while axonemal dynein is involved in beating. In both cases, the binding requires frequent association/disassociation between the microtubule and MTBD, and involves highly negatively charged microtubules, including non-structured C-terminal domains (E-hooks), and an MTBD interface that is positively charged. This indicates that electrostatics play an important role in the association process. Here, we show that the cytoplasmic MTBD binds electrostatically tighter to microtubules than to the axonemal MTBD, but the axonemal MTBD experiences interactions with microtubule E-hooks at longer distances compared with the cytoplasmic MTBD. This allows the axonemal MTBD to be weakly bound to the microtubule, while at the same time acting onto the microtubule via the flexible E-hooks, even at MTBD⁻microtubule distances of 45 Å. In part, this is due to the charge distribution of MTBDs: in the cytoplasmic MTBD, the positive charges are concentrated at the binding interface with the microtubule, while in the axonemal MTBD, they are more distributed over the entire structure, allowing E-hooks to interact at longer distances. The dissimilarities of electrostatics in the cases of axonemal and cytoplasmic MTBDs were found not to result in a difference in conformational dynamics on MTBDs, while causing differences in the conformational states of E-hooks. The E-hooks' conformations in the presence of the axonemal MTBD were less restricted than in the presence of the cytoplasmic MTBD. In parallel with the differences, the common effect was found that the structural fluctuations of MTBDs decrease as either the number of contacts with E-hooks increases or the distance to the microtubule decreases.

Dataset Information

Axonemal dynein light chain-1 locates at the microtubule-binding domain of the ? heavy chain.

Publications

Axonemal dynein light chain-1 locates at the microtubule-binding domain of the γ heavy chain.

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