The Cytoskeleton of Acanthamoeba

The Cytoskeleton of Acanthamoeba (Neff)

Page updated 24/8/02

One particular strain of Acanthamoeba, has been used by two major labs to study the eukaryotic actin cytoskeleton. This Acanthamoeba castellanii ATCC, isolated by Neff in a park in San Francisco California U.S. in 1959. This amoeba can be grown in huge quantities relatively cheaply, so that large amounts of proteins can be purified for biochemical characterization. Acanthamoeba is particularly actin-rich some 20% of the total protein is actin (Gordon et al, 1976). This approach has lead to the discovery of actin-binding proteins such as the very important Arp2/3 complex and members of the myosin family, but has also allowed detailed analysis of proteins before cloning. Proteins isolated from the amoeba have been crystallised (* below).

Protein	Function	Reference
Acan125	Binds Myosin I at membrane	Xu et al, 1995
Actobindin	Actin monomer sequestering	Lambooy & Korn, 1986
Actophorin *	Actin filament severing and depolymerising protein (see ADF/cofilin)	Cooper et al, 1986; * Magnus et al, 1991;* Leonard et al, 1997
Actin	Polymerises to produce microfilaments	Gordon et al, 1976
Alpha actinin	Actin bundling protein
ABP110	Binds actin in an ATP-dependent manner	Ueno & Korn, 1986
Arp2/3 complex	Actin nucleation and pointed end capping	Machesky et al, 1994
Gelation factors	Actin microfilament cross-linking proteins	Maruta & Korn, 1977a


Myosin I	Moves vesicles around cell on microfilaments	Pollard & Korn, 1973
Myosin II	Produces contraction required for cytokinesis	Maruta & Korn, 1977b
Myosin HMW
Profilin I *	Actin monomer binding and signalling protein.	* Magnus et al, 1986,88
Profilin II	Actin monomer binding and signalling protein.
Table 1 Actin binding proteins purified from Acanthamoeba castellanii

References:-

Cooper, J. A., Blum, J. D., Williams, R. C. & Pollard, T. D. (1986) Purification and Characterization of Actophorin, a New 15,000-Dalton Actin-binding Protein from Acanthamoeba castellanii. J. Biol. Chem. 261, 477-485.

Gordon, D., Eisenberg, E. & Korn, E. (1976) Characterization of cytoplasmic actin isolated from Acanthamoeba castellanii by a new method. J. Biol. Chem. 251, 4778-4786.

Korn, E. D. (1980) Biochemistry of actomyosin-dependent cell motility in Acanthamoeba castellanii. in The Eukaryotic Microbial Cell (Gooday, G. W., Llyod, D. & Trinci, A. P. J., eds) pp. 253-273, Cambridge University Press, Cambridge.

Lambooy, P. K. & Korn, E. D. (1986) Purification and characterization of actobindin, a new actin monomer binding protein from Acanthamoeba castellanii. J.Biol.Chem. 261, 17150-17155.

Leonard, S. A., Gittis, A. G., Petrulla, E. C., Pollard, T. D. & Lattman, E. E. (1997) Crystal structure of the actin-binding protein actophorin from Acanthamoeba, Nature (structural Biology). 4, 369-373.

Machesky, L. M., Atkinson, S. J., Ampe, C., Vandekerckhove, J. & Pollard, T. D. (1994) Purification of a cortical complex containing two unconventional actins from Acanthamoeba by affinity chromatography on profilin-agarose. J. Cell Biol. 127, 107-115.

Pollard, T. D. & Korn, E. D. (1973) Acanthamoeba myosin I. Isolation from Acanthamoeba castellanii of an enzyme similar to muscle myosin., J.Biol.Chem. 248, 4682-4690.

Magnus, K. A., Lattman, E. E., Kaiser, D. A. & Pollard, T. D. (1988) The crystal-structure of Acanthamoeba profilin-I at 2.4 a-degrees resolution, Biophysical Journal. 53.

Magnus, K. A., Lattman, E. E., Sato, M. & Pollard, T. D. (1986) Crystallization of Acanthamoeba profilin-I, J.Biol.Chem. 261, 3360-3361.

Maruta, H. & Korn, E. D. (1977a) Acanthamoeba myosin II. J.Biol.Chem. 252, 6501-6509.

Maruta, H. & Korn, E. D. (1977b) Purification from Acanthamoeba castellanii of proteins that induce gelation and syneresis of F-actin, J.Biol.Chem. 252, 399-402.

Pollard, T.D., K.A. Magnus, S.K. Doberstein, P. Goldschmidt-Clermont, D.A. Kaiser, L.M. Machesky, S.K.Maciver, D.L. Rimm, and D. Wachsstock. (1989). Structure-function studies of the actin filament system of Acanthamoeba. In: "Springer series in Biophysics" (U. Aebi, J. Engel, eds), Vol. 3 "Cytoskeletal and Extracellular Proteins", 2nd Intern. Symp. European Biophys. Soc., Gwatt, Switzerland, pp. 271-279, London (1989).

Ueno, T. & Korn, E. D. (1986) Isolation and partial characterization of a 110-kD dimer actin-binding protein, J.Cell Biol. 103, 621-630.

Xu, P., Zot, A. S. & Zot, H. G. (1995) Identification of Acan125 as a myosin-I-binding protein present with myosin-I on cellular membranes, J.Biol.Chem. 270, 25316-25319.