In order to identify and reveal the
proteins related to encystment of the ciliate Euplotes encysticus, we analyzed variation in the abundance of the
proteins isolated from the resting
cyst comparing with
proteins in the vegetative cell. 2-D electrophoresis, MALDI-TOF MS techniques and Bioinformatics were used for
proteome separation, quantification and identification. The comparative proteomics studies revealed 26
proteins with changes on the expression in the resting
cysts, including 12 specific
proteins and 14 differential
proteins. 12 specific
proteins and 10 out of the 14 differential
proteins were selected and identified by MALDI-TOF MS. The identified specific
proteins with known functions included type II cytoskeletal 1,
keratin, Nop16 domain containing
protein,
protein arginine n-methyltransferase, epsilon-
trimethyllysine hydroxylase and
calpain-like
protein. The identified differential
proteins with known functions included
Lysozyme C,
keratinocyte growth factor,
lysozyme homolog AT-2,
formate acetyltransferase, alpha S1
casein and
cold-shock protein. We discussed the functions of these
proteins as well as their contribution in the process of encystment. These identified
proteins covered a wide range of molecular functions, including gene regulation,
RNA regulation,
proteins degradation and oxidation resistance, stress response, material transport and cytoskeleton organization. Therefore, differential expression of these
proteins was essential for cell morphological and physiological changes during encystment. This suggested that the peculiar
proteins and differential
proteins might play important roles in the process of the vegetative cells transforming into the resting
cysts. These observations may be novel findings that bring new insights into the detailed mechanisms of dormancy.