Enzymatic activity and filament assembly of <i>Acanthamoeba</i> myosin II are regulated by adjacent domains at the end of the tail

Atkinson, Mark A.; Appella, Ettore; Corigliano-Murphy, M. Angela; Korn, Edward D.

doi:10.1016/0014-5793(88)80132-7

Cited by 10 publications

(8 citation statements)

References 26 publications

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“…This suggests, but does not prove, that filaments are required for the actin-activated Mg2+-ATPase activity of myosin I1 to be expressed. This hypothesis is further strengthened by observations by Kiehart and Pollard [56] that monoclonal antibodies to the carboxyl-terminal region of the tail depolymerize myosin II filaments and inactivate their actin-activated Mg2+-ATPase activity and our demonstration [57] that polyclonal antibodies raised against a synthetic peptide with the sequence of the helical region immediately preceding the non-helical tailpiece have similar properties.…”

Section: Mechanism Of Myosin II Regulation By Phosphorylationsupporting

confidence: 66%

“…The major question we have addressed with respect to myosin 11 is how phosphorylation of 3 (or 4) serines at the very tip of the tail can inhibit the actinactivated Mg2+-ATPase activity that resides in the globular head [53] (see Fig. 4).…”

Section: Mechanism Of Myosin II Regulation By Phosphorylationmentioning

confidence: 99%

“…We next made use of the fact that limited chymotrypsin digestion of myosin I1 selectively removes the carboxyl-terminal 66 amino acids [53] with no other effects on the heavy chains or on either pair of light chains [49] (Fig. 4).…”

Section: Mechanism Of Myosin II Regulation By Phosphorylationmentioning

confidence: 99%

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Structure‐function studies on Acanthamoeba myosins IA, IB, and II

Korn

Atkinson

Brzeska

et al. 1988

J of Cellular Biochemistry

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Myosins IA and IB are globular proteins with only a single, short (for myosins) heavy chain (140,000 and 125,000 daltons for IA and IB, respectively) and are unable to form bipolar filaments. The amino acid sequence of IB heavy chain shows 55% similarity to muscle myosins in the N-terminal 670 residues, which contain the active sites, and a unique 500-residue C-terminus highly enriched in proline, glycine, and alanine. The C-terminal region contains a second actin-binding site which allows myosins IA and IB to cross-link actin filaments and support contractile activity. Myosins IA and IB are regulated solely by phosphorylation of one serine on the heavy chain positioned between the catalytic site and the actin-binding site that activates ATPase. Myosin II is a more conventional myosin in composition (two heavy chains and two pairs of light chains), heavy chain sequence (globular head 45% identical to muscle myosins and a coiled-coil helical tail), and structure (bipolar filaments). The tail of myosin II is much shorter than that of other conventional myosins, and it contains a 25 amino acid sequence in which helical structure is predicted to be weak or absent. The position of this sequence corresponds to the position of a bend in the monomer. Myosin II heavy chains also have a 29-residue nonhelical tailpiece which contains three regulatory, phosphorylatable serines. Phosphorylation at the tip of the tail regulates ATPase activity in the globular head apparently through an effect on filament structure.

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Section: Mechanism Of Myosin II Regulation By Phosphorylationsupporting

confidence: 66%

Section: Mechanism Of Myosin II Regulation By Phosphorylationmentioning

confidence: 99%

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Structure‐function studies on Acanthamoeba myosins IA, IB, and II

Korn

Atkinson

Brzeska

et al. 1988

J of Cellular Biochemistry

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“…Previous work had shown that phosphorylation of two or more of these serines (residues 1489, 1494, 1499, and 1504) correlates with, and was assumed to be responsible for, inactivation of AMII's actin-activated MgATPase activity (5,6). Also, it had been concluded that only filamentous AMII has actin-activated MgATPase activity (7,8), and it was inferred that the ATPase activity is regulated by a change in the conformation of the bipolar minifilaments (9)(10)(11). However, detailed studies by the Pollard laboratory found no significant differences in either the polymerization properties or electron microscopic images of minifilaments of phosphorylated and dephosphorylated myosins (12)(13)(14)(15)(16).…”

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confidence: 99%

Regulation of the filament structure and assembly ofAcanthamoebamyosin II by phosphorylation of serines in the heavy-chain nonhelical tailpiece

Liu

Hong

Shu

et al. 2012

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

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Acanthamoeba myosin II (AMII) has two heavy chains ending in a 27-residue nonhelical tailpiece and two pairs of light chains. In a companion article, we show that five, and only five, serine residues can be phosphorylated both in vitro and in vivo: Ser639 in surface loop 2 of the motor domain and serines 1489, 1494, 1499, and 1504 in the nonhelical tailpiece of the heavy chains. In that paper, we show that phosphorylation of Ser639 down-regulates the actin-activated MgATPase activity of AMII and that phosphorylation of the serines in the nonhelical tailpiece has no effect on enzymatic activity. Here we show that bipolar tetrameric, hexameric, and octameric minifilaments of AMII with the nonhelical tailpiece serines either phosphorylated or mutated to glutamate have longer bare zones and more tightly clustered heads than minifilaments of unphosphorylated AMII, irrespective of the phosphorylation state of Ser639. Although antiparallel dimers of phosphorylated and unphosphorylated myosins are indistinguishable, phosphorylation inhibits dimerization and filament assembly. Therefore, the different structures of tetramers, hexamers, and octamers of phosphorylated and unphosphorylated AMII must be caused by differences in the longitudinal stagger of phosphorylated and unphosphorylated bipolar dimers and tetramers. Thus, although the actin-activated MgATPase activity of AMII is regulated by phosphorylation of Ser639 in loop 2 of the motor domain, the structure of AMII minifilaments is regulated by phosphorylation of one or more of four serines in the nonhelical tailpiece of the heavy chain.A s summarized in the accompanying paper (1), Acanthamoeba myosin II (AMII) is a typical class II myosin with two heavy chains and two pairs of light chains (2, 3). The coiled-coil helical tails of the heavy chains terminate with a 27-residue nonhelical tailpiece, 1483PSSRGGSTRGASARGASVRAGSARAEE1509, which has a pattern of four contiguous repeats of XXSXR (4). Previous work had shown that phosphorylation of two or more of these serines (residues 1489, 1494, 1499, and 1504) correlates with, and was assumed to be responsible for, inactivation of AMII's actin-activated MgATPase activity (5, 6). Also, it had been concluded that only filamentous AMII has actin-activated MgATPase activity (7, 8), and it was inferred that the ATPase activity is regulated by a change in the conformation of the bipolar minifilaments (9-11). However, detailed studies by the Pollard laboratory found no significant differences in either the polymerization properties or electron microscopic images of minifilaments of phosphorylated and dephosphorylated myosins (12-16).The earlier studies were carried out with purified endogenous myosin. To avoid possible complications in enzymatic and structural studies caused by the partial phosphorylation of purified endogenous myosin and incomplete dephosphorylation by phosphatase, we initiated studies on the enzymatic activity and structure of expressed recombinant wild-type, truncated, and mutant myosins before and after phos...

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“…Furthermore, because the actin-activated ATPase activity of copolymers of dephosphorylated and phosphorylated AMII was less than the activity of equivalent mixtures of homopolymers, it was suggested that regulation of ATPase activity occurred at the filament level (16,17). From these and other (18)(19)(20) data, it was inferred that only filamentous AMII has phosphorylation-regulated actin-activated ATPase activity and that the activity of each molecule in a filament is a function not of its own level of phosphorylation but of the phosphorylation level of the filament as a whole. Thus, regulation of the actin-activated ATPase of AMII would involve a conformational change in the myosin filament.…”

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confidence: 99%

Regulation of the actin-activated MgATPase activity ofAcanthamoebamyosin II by phosphorylation of serine 639 in motor domain loop 2

Liu¹,

Lee²,

Cai³

et al. 2012

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

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It had been proposed previously that only filamentous forms of Acanthamoeba myosin II have actin-activated MgATPase activity and that this activity is inhibited by phosphorylation of up to four serine residues in a repeating sequence in the C-terminal nonhelical tailpiece of the two heavy chains. We have reinvestigated these issues using recombinant WT and mutant myosins. Contrary to the earlier proposal, we show that two nonfilamentous forms of Acanthamoeba myosin II, heavy meromyosin and myosin subfragment 1, have actin-activated MgATPase that is down-regulated by phosphorylation. By mass spectroscopy, we identified five serines in the heavy chains that can be phosphorylated by a partially purified kinase preparation in vitro and also are phosphorylated in endogenous myosin isolated from the amoebae: four serines in the nonhelical tailpiece and Ser639 in loop 2 of the motor domain. S639A mutants of both subfragment 1 and full-length myosin had actin-activated MgATPase that was not inhibited by phosphorylation of the serines in the nonhelical tailpiece or their mutation to glutamic acid or aspartic acid. Conversely, S639D mutants of both subfragment 1 and full-length myosin were inactive, irrespective of the phosphorylation state of the serines in the nonhelical tailpiece. To our knowledge, this is the first example of regulation of the actin-activated MgATPase activity of any myosin by modification of surface loop 2.

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Enzymatic activity and filament assembly of Acanthamoeba myosin II are regulated by adjacent domains at the end of the tail

Cited by 10 publications

References 26 publications

Structure‐function studies on Acanthamoeba myosins IA, IB, and II

Structure‐function studies on Acanthamoeba myosins IA, IB, and II

Regulation of the filament structure and assembly ofAcanthamoebamyosin II by phosphorylation of serines in the heavy-chain nonhelical tailpiece

Regulation of the actin-activated MgATPase activity ofAcanthamoebamyosin II by phosphorylation of serine 639 in motor domain loop 2

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