dictyNews
Electronic Edition
Volume 40, number 18
Jul 31, 2014

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=========
Abstracts
=========

Cross-species Functional Complementation of Cellulose Synthase 
during the development of Cellular Slime Molds

Hidekazu Kuwayama, Takeru Tohyama, Hideko Urushihara
Faculty of Life and Environmental Sciences, University of 
Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan

Development, Growth & Differentiation, in press

Cellulose is a major and important component of the extracellular 
matrix during the development of Dictyostelium discoideum. Upon 
starvation, solitary amoebae of D. discoideum gather and form 
fruiting bodies in which cells differentiate into stalk cells 
and spores. The stalk tubes and walls of spores and stalk cells 
are made of cellulose. In the genus Acytostelium, however, all 
cells are destined to become spores and the stalks comprise only 
a cellulose tube, suggesting species-specific regulation of 
cellulose synthesis. In this study, we cloned a putative cellulose 
synthase gene (cesA) of Acytostelium subglobosum and performed 
comparative analyses with the D. discoideum cellulose synthase 
gene (dcsA). Although the deduced amino acid sequences were 
highly conserved between cesA and dcsA, the numbers of 
transmembrane spans preceding the catalytic domain were 
dissimilar; 2 and 3, respectively. Since ectopic expression 
of cesA in dcsA-null cells failed to restore the developmental 
defects of the mutant, we constructed a series of chimerical 
genes for complementation analyses and found that the catalytic 
domain of cesA was functional in D. discoideum cells if the 
preceding transmembrane region was swapped with dcsA. The 
non-functional products that contained the cesA-derived 
transmembrane region were localized to lysosomes. These results 
indicate that the transmembrane region of cellulose synthase is 
essential for proper accumulation of cellulose during the 
development of D. discoideum and that its differential 
localization in A. subglobosum may be related to the 
characteristic morphogenesis in this species.

Submitted by Hidekazu Kuwayama [hidekuwayama@biol.tsukuba.ac.jp]
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[End dictyNews, volume 40, number 18]