Molecular and biochemical characterization of a novel actin bundling protein in Acanthamoeba.
10.3347/kjp.2006.44.4.331
- Author:
Joanna It Itan ALAFAG
1
;
Eun Kyung MOON
;
Yeon Chul HONG
;
Dong Il CHUNG
;
Hyun Hee KONG
Author Information
1. Department of Parasitology, Kyungpook National University School of Medicine, Daegu 700-422, Korea. hhkong@mail.knu.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Acanthamoeba;
actin bundling protein;
EF-hand
- MeSH:
Transfection;
Sequence Analysis, DNA;
Sequence Alignment;
Microscopy, Electron, Transmission;
Microfilament Proteins/*chemistry/genetics/*metabolism;
EF Hand Motifs;
DNA, Complementary;
Culture Media;
Cloning, Molecular;
Animals;
Amino Acid Sequence;
Actins/*metabolism;
Acanthamoeba/genetics/growth & development/*metabolism
- From:The Korean Journal of Parasitology
2006;44(4):331-341
- CountryRepublic of Korea
- Language:English
-
Abstract:
Actin binding proteins play key roles in cell structure and movement particularly as regulators of the assembly, stability and localization of actin filaments in the cytoplasm. In the present study, a cDNA clone encoding an actin bundling protein named as AhABP was isolated from Acanthamoeba healyi, a causative agent of granulomatous amebic encephalitis. This clone exhibited high similarity with genes of Physarum polycephalum and Dictyostelium discoideum, which encode actin bundling proteins. Domain search analysis revealed the presence of essential conserved regions, i.e., an active actin binding site and 2 putative calcium binding EF-hands. Transfected amoeba cells demonstrated that AhABP is primarily localized in phagocytic cups, peripheral edges, pseudopods, and in cortical cytoplasm where actins are most abundant. Moreover, AhABP after the deletion of essential regions formed ellipsoidal inclusions within transfected cells. High-speed co-sedimentation assays revealed that AhABP directly interacted with actin in the presence of up to 10 micrometer of calcium. Under the electron microscope, thick parallel bundles were formed by full length AhABP, in contrast to the thin actin bundles formed by constructs with deletion sites. In the light of these results, we conclude that AhABP is a novel actin bundling protein that is importantly associated with actin filaments in the cytoplasm.
