Expression of a 66-kD Heat Shock Protein Associated with the Process of Cyst Formation of a True Slime Mold, Physarum polycephalum.

Cell Structure and Function

Hikoichi Sakai¹  Kimiko Murakami-Murofushi²  Hiromu Murofushi¹  Yukiko Shimada²  Michiyo Yokota²  Ichiro Yahara³  Tomoko Kasakura²  Yoshihiko Miyata³ 

[1] Department of Biophysics and Biochemistry, Faculty of Science, The University of Tokyo;Department of Biology, Faculty of Science, Ochanomizu University;Department of Cell Biology, The Tokyo Metropolitan Institute of Medical Science

关键词: cyst formation;    heat shock protein;    actin binding protein;    stress protein;    Physarum polycephalum;   

DOI  :  10.1247/csf.17.301

学科分类：分子生物学，细胞生物学和基因

来源: Japan Society for Cell Biology

【 摘 要 】

References(28)Cited-By(17)Under unfavorable conditions for growth, haploid myxoamoebae of Physarum polycephalum retracted their pseudopodia and changed their cell shape into disk-like form, after which they constructed the cell walls to form microcysts. These morphological changes of haploid cells were associated with changes in intracellular distribution of actin filaments. Staining with phalloidin showed that actin filaments were almost uniformly distributed throughout the cytoplasm of the myxoamoebae. Whenthese cells were transferred to a cyst-inducing medium, the actin structures changed into short rods or dots, after which the rods/dots disappeared in the microcysts. Anincubation of the myxoamoebaein the cyst-inducing medium caused the synthesis of several proteins, among which a 66-kD protein was most prominently induced. The morphological changes and the induction of the 66-kD protein was pronounced at elevated temperatures, e.g. 40°C. The 66-kD protein was not induced, however, when plasmodia of the same species were incubated at 40°C. W efound that the 66- kD protein was co-precipitated with polymerized actin and bound to ATP-agarose. A double staining of the disk-shaped cells with anti-66-kD protein antibody and phalloidin revealed superimposable localization of the 66-kD protein and actin filaments in the short rods or dots. Although the induction of the 66-kD protein was enhanced at high temperatures, the protein was immunologically unrelated to the common heat shock proteins, HSP70 and HSP90, those are highly conserved during evolution. These results indicate that the 66-kD protein is a novel heat shock protein which is specifically expressed during cyst formation.

【 授权许可】

Unknown