Myosin VI is a processive motor with a large step size

Rock, Ronald S.; Rice, Sarah E.; Wells, Amber L.; Purcell, Thomas J.; Spudich, James A.; Sweeney, H. Lee

doi:10.1073/pnas.191512398

Cited by 363 publications

(401 citation statements)

References 30 publications

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“…A large stroke size is probably essential to the processive stepping mechanism of dimeric myosin VI, which moves along actin with Ϸ36-nm strides, matching the pseudorepeat of the actin helix (4,5). Unlike myosin V, myosin VI has not used multiple IQ repeats to achieve a large stroke.…”

Section: Discussionmentioning

confidence: 99%

“…A new puzzle arose when the stepping behavior of dimeric myosin VI was characterized by using single molecule techniques (4,5). Myosin VI, like myosin V, walks processively along actin by using a long stride that approximately matches the Ϸ36-nm pseudorepeat of the actin filament.…”

Section: A Long Stride and A Long Strokementioning

confidence: 99%

“…Class VI myosins are highly specialized (Ϫ)-end-directed motors involved in a growing list of functions in animal cells, including endocytosis, cell migration, and maintenance of stereociliar membrane tension (2). Initial biophysical characterization (3)(4)(5) of myosin VI raised two important questions concerning the structural basis of its unique motor properties. First, how does the motor achieve reverse directionality?…”

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confidence: 99%

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The power stroke of myosin VI and the basis of reverse directionality

Bryant

Altman

Spudich

2007

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

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Myosin VI supports movement toward the (؊) end of actin filaments, despite sharing extensive sequence and structural homology with (؉)-end-directed myosins. A class-specific stretch of amino acids inserted between the converter domain and the lever arm was proposed to provide the structural basis of directionality reversal. Indeed, the unique insert mediates a 120°redirection of the lever arm in a crystal structure of the presumed poststroke conformation of myosin VI [Mé né trey J, Bahloul A, Wells AL, Yengo CM, Morris CA, Sweeney HL, Houdusse A (2005) Nature 435:779 -785]. However, this redirection alone is insufficient to account for the large (؊)-end-directed stroke of a monomeric myosin VI construct. The underlying motion of the myosin VI converter domain must therefore differ substantially from the power stroke of (؉)-end-directed myosins. To experimentally map out the motion of the converter domain and lever arm, we have generated a series of truncated myosin VI constructs and characterized the size and direction of the power stroke for each construct using dual-labeled gliding filament assays and optical trapping. Motors truncated near the end of the converter domain generate (؉)-end-directed motion, whereas longer constructs move toward the (؊) end. Our results directly demonstrate that the unique insert is required for directionality reversal, ruling out a large class of models in which the converter domain moves toward the (؊) end. We suggest that the lever arm rotates Ϸ180°between pre-and poststroke conformations.actin ͉ molecular motor ͉ pointed end ͉ swinging cross-bridge T he basic actomyosin motor has been embellished, altered, and reused many times through the evolution of diverse members of the myosin superfamily (1). Class VI myosins are highly specialized (Ϫ)-end-directed motors involved in a growing list of functions in animal cells, including endocytosis, cell migration, and maintenance of stereociliar membrane tension (2). Initial biophysical characterization (3-5) of myosin VI raised two important questions concerning the structural basis of its unique motor properties. First, how does the motor achieve reverse directionality? And second, how does dimeric myosin VI take long steps along actin, matching the stride of myosin V without the apparent benefit of a long lever arm?A Backward-Moving Myosin Myosin VI attracted attention as a candidate for a (Ϫ)-enddirected motor after the identification of a class-specific insert following the converter domain. In the swinging cross-bridge model of actomyosin function, the converter domain transmits motion from the myosin head to the C-terminal lever arm, generating a directed power stroke. Wells et al. (3) hypothesized that a structure inserted between the converter domain and the lever arm could redirect the stroke and lead to backward movement. The predicted reverse directionality of myosin VI was experimentally confirmed (3), but the precise mechanism of this remarkable adaptation remained unclear, including whether the unique insert was necess...

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Section: Discussionmentioning

confidence: 99%

Section: A Long Stride and A Long Strokementioning

confidence: 99%

mentioning

confidence: 99%

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The power stroke of myosin VI and the basis of reverse directionality

Bryant

Altman

Spudich

2007

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

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“…Presumably, myosin VI has an elastic region which can be elongated, and takes a diffusive search during a step to create a large displacement with a significant variability. 29,30 Studies have shown that myosin VI is involved in cell migration, spermatoge-FIGURE 2. Structures of kinesin and myosin V. Conventional kinesin and myosin V form a dimer and walk processively on their track.…”

Section: Molecular Motorsmentioning

confidence: 99%

Fluorescence Imaging with One Nanometer Accuracy: Application to Molecular Motors

2005

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We introduce the technique of FIONA, fluorescence imaging with one nanometer accuracy. This is a fluorescence technique that is able to localize the position of a single dye within ∼1 nm in the x-y plane. It is done simply by taking the point spread function of a single fluorophore excited with wide field illumination and locating the center of the fluorescent spot by a two-dimensional Gaussian fit. We motivate the development of FIONA by unraveling the walking mechanism of the molecular motors myosin V, myosin VI, and kinesin. We find that they all walk in a hand-over-hand fashion.

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“…They are also known to be involved in cell migration, cell invasiveness, plasminogen activity and drug and radiation resistance (Martens et al, 1999). Myosin VI is expressed in a variety of cell types and is thought to play a role in membrane trafficking and and endocytosis (Rock et al, 2001;Yoshimura et al, 2001). Tubulin beta 4 is downregulated in hepatoma cells than in normal liver cells (Yu et al, 2000).…”

Section: Genes Related To Cell Adhesion and Motilitymentioning

confidence: 99%

Differential gene expression profiles of gastric cancer cells established from primary tumour and malignant ascites

et al. 2002

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Advanced gastric cancer is often accompanied by metastasis to the peritoneum, resulting in a high mortality rate. Mechanisms involved in gastric cancer metastasis have not been fully clarified because metastasis involves multiple steps and requires a combination of altered expressions of many different genes. Thus, independent analysis of any single gene would be insufficient to understand all of the aspects of gastric cancer peritoneal dissemination. In this study, we performed a global analysis of the differential gene expression of a gastric cancer cell line established from a primary main tumour (SNU-1) and of other cell lines established from the metastasis to the peritoneal cavity (SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB). The application of a high-density cDNA microarray method made it possible to analyse the expression of approximately 21 168 genes. Our examinations of SNU-5, SNU-16, SNU-620, KATO-III and GT3TKB showed that 24 genes were upregulated and 17 genes down-regulated besides expression sequence tags. The analysis revealed the following altered expression such as: (a) up-regulation of CD44 (cell adhesion), keratins 7, 8, and 14 (epitherial marker), aldehyde dehydrogenase (drug metabolism), CD9 and IP3 receptor type3 (signal transduction); (b) down-regulation of IL2 receptor g, IL4-Stat (immune response), p27 (cell cycle) and integrin b4 (adhesion) in gastric cancer cells from malignant ascites. We then analysed eight gastric cancer cell lines with Northern blot and observed preferential up-regulation and down-regulation of these selected genes in cells prone to peritoneal dissemination. Reverse transcriptase -polymerase chain reaction confirmed that several genes selected by DNA microarray were also overexpressed in clinical samples of malignant ascites. It is therefore considered that these genes may be related to the peritoneal dissemination of gastric cancers. The results of this global gene expression analysis of gastric cancer cells with peritoneal dissemination, promise to provide a new insight into the study of human gastric cancer peritoneal dissemination.

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Myosin VI is a processive motor with a large step size

Cited by 363 publications

References 30 publications

The power stroke of myosin VI and the basis of reverse directionality

The power stroke of myosin VI and the basis of reverse directionality

Fluorescence Imaging with One Nanometer Accuracy: Application to Molecular Motors

Differential gene expression profiles of gastric cancer cells established from primary tumour and malignant ascites

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