Characterization of Entamoeba histolytica alpha-actinin2.
We have cloned and characterized a second alpha-actinin isoform in Entamoeba histolytica. This protein, alpha-actinin2, has a N-terminal actin-binding domain, a C-terminal calcium-binding domain and an intervening rod domain containing two spectrin repeats. The protein binds and cross-links actin filaments in a calcium-dependent manner. Therefore alpha-actinin2 is a genuine alpha-actinin except for the shorter rod domain compared to the rod domain of isoforms of higher organisms. A alpha-actinin-like protein has previous been implicated in the adherence to the host cell and infection. It is therefore possible that alpha-actinin2 is involved in mechanism of infection, and in particular in reorganisation of the parasite's cytoskeleton that follows on adherence. E. histolytica alpha-actinin2 represents one of the first members of the spectrin superfamily where well defined spectrin repeats are found. The isolation and characterization of this second alpha-actinin isoform is valuable not only into the study of E. histolytica infection mechanisms, but also for understanding the evolution processes of the spectrin superfamily.
Virel
Ana
A
Biochemistry, Umeå University, SE-901 87 Umeå, Sweden.
Addario
Barbara
B
Backman
Lars
L
D000185:Actinin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000199:Actins / Q000378:metabolism / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002118:Calcium / Q000378:metabolism; D003001:Cloning, Molecular; D004748:Entamoeba histolytica / Q000235:genetics* / Q000378:metabolism*; D047468:Immunoprecipitation; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary
D000199:Actins; D020033:Protein Isoforms; D000185:Actinin; D002118:Calcium