Open AccessExpression of Conventional and Unconventional Actins in Chlamydomonas reinhardtii upon Deflagellation and Sexual Adhesion
Author(s) -
Masafumi Hirono,
Satomi Uryu,
Akio Ohara,
Takako Kato-Minoura,
Ritsu Kamiya
Publication year - 2003
Publication title -
eukaryotic cell
Language(s) - English
Resource type - Journals
eISSN - 1535-9778
pISSN - 1535-9786
DOI - 10.1128/ec.2.3.486-493.2003
Subject(s) - nap , biology , chlamydomonas reinhardtii , microbiology and biotechnology , actin , chlamydomonas , wild type , mutant , flagellum , gene , genetics , neuroscience
Chlamydomonas has two actin genes, one coding for a conventional actin and the other coding for a highly divergent actin. The divergent actin NAP (for "novel actin-like protein") is expressed only negligibly in wild-type cells but abundantly in a null mutant of conventional actin, the ida5 mutant. The presence of the dormant NAP gene suggests that NAP may also have its own function in wild-type cells under some conditions. However, no specific functions have been suggested. In this study, we examined the expression of actin and NAP in wild-type and ida5 cells under conditions where actin function has been shown to be important. We found that deflagellation induces the expression of NAP as well as that of actin in wild-type cells. The expressed NAP becomes localized to the regrown flagella, apparently without being associated with dynein. Mating of gametes also increased the expression of actin in wild-type cells and that of NAP in ida5 cells, resulting in accumulation of these proteins in flagella (in both wild-type and ida5 cells) and the fertilization tubule (only in wild-type cells). However, it did not induce significant NAP expression in wild-type cells. These and other observations suggest that the expression of actin and NAP mRNAs is controlled by two discrete mechanisms and that NAP plays a role in flagellar formation in wild-type cells.