Acanthamoeba Myosins and Kinesin

Korn, E D.

Abstract

Structure-function studies have shown that at least 2 of the 3 regulatory, phosphorylatable serines can be proteolytically removed from the non-helical tailpiece of the Acanthamoeba myosin II heavy chain with essentially no effect on filament formation or phosphorylation-regulatable actin-activated ATPase activity. The positions of the ATP binding site, phosphorylation site and two different actin-binding sites have been localized in Acanthamoeba myosin IA and IB. The phosphorylated amino acid in IA was shown to be threonine while it is serine in IB. The sequence around the PThr has been determined. A third Acanthamoeba myosin I isoform has been purified and characterized. Myosin 1 has been shown to be reversibly bound (Kd approximately 0.05 muM) to the plasma membrane of Acanthamoeba through saturable sites that appear to be independent of actin and from which the myosin can be dissociated at high ionic strength. Studies with Dictyostelium suggest an important role for myosin I at the leading edge of motile cells, a region that is devoid of myosin II but is enriched with actin filaments.

Funding Agency

• Agency: National Institute of Health (NIH)
• Institute: National Heart, Lung, and Blood Institute (NHLBI)
• Type: Intramural Research (Z01)
• Project #: 1Z01HL000506-14
• Application #: 3919992
• Support Year: 14
• Fiscal Year: 1988

Institution

• Name: U.S. National Heart Lung and Blood Inst
• Country: United States

Publications

Baek, Kyuwon; Liu, Xiong; Ferron, Francois et al. (2008) Modulation of actin structure and function by phosphorylation of Tyr-53 and profilin binding. Proc Natl Acad Sci U S A 105:11748-53

Hwang, Kae-Jung; Mahmoodian, Fatemeh; Ferretti, James A et al. (2007) Intramolecular interaction in the tail of Acanthamoeba myosin IC between the SH3 domain and a putative pleckstrin homology domain. Proc Natl Acad Sci U S A 104:784-9

Szczepanowska, Joanna; Korn, Edward D; Brzeska, Hanna (2006) Activation of myosin in HeLa cells causes redistribution of focal adhesions and F-actin from cell center to cell periphery. Cell Motil Cytoskeleton 63:356-74

Liu, Xiong; Shu, Shi; Hong, Myoung-Soon S et al. (2006) Phosphorylation of actin Tyr-53 inhibits filament nucleation and elongation and destabilizes filaments. Proc Natl Acad Sci U S A 103:13694-9

Shu, Shi; Mahadeo, Dana C; Liu, Xiong et al. (2006) S-adenosylhomocysteine hydrolase is localized at the front of chemotaxing cells, suggesting a role for transmethylation during migration. Proc Natl Acad Sci U S A 103:19788-93

Shu, Shi; Liu, Xiong; Korn, Edward D (2005) Blebbistatin and blebbistatin-inactivated myosin II inhibit myosin II-independent processes in Dictyostelium. Proc Natl Acad Sci U S A 102:1472-7

Liu, Xiong; Shu, Shi; Kovacs, Mihaly et al. (2005) Biological, biochemical, and kinetic effects of mutations of the cardiomyopathy loop of Dictyostelium myosin II: importance of ALA400. J Biol Chem 280:26974-83

Ishikawa, Takashi; Cheng, Naiqian; Liu, Xiong et al. (2004) Subdomain organization of the Acanthamoeba myosin IC tail from cryo-electron microscopy. Proc Natl Acad Sci U S A 101:12189-94

Korn, Edward D (2004) The discovery of unconventional myosins: serendipity or luck? J Biol Chem 279:8517-25

Brzeska, Hanna; Szczepanowska, Joanna; Matsumura, Fumio et al. (2004) Rac-induced increase of phosphorylation of myosin regulatory light chain in HeLa cells. Cell Motil Cytoskeleton 58:186-99