Calcium-Calmodulin-Involved Heat Shock Response of Neoporphyra haitanensis
Hongyan Zheng, Yan Xu, Dehua Ji, Kai Xu, Changsheng Chen, Wenlei Wang, Chaotian Xie
Abstract
Increasing global temperatures have seriously affected the sustainable development of Neoporphyra haitanensis cultivation. Although several pathways are reported to be involved in the response of N. haitanensis to heat stress, it is unknown which ones are activated by signal transduction. Previously, we detected a large influx of calcium ions (Ca 2+ ) in N. haitanensis under heat stress. In this study, we further investigated the specificity of Ca 2+ signaling and how is it transduced. Transmission electron microscopy and Fv/Fm analyses showed that the Ca 2+ signal derived from extracellular Ca 2+ formed at the early stage of the response to heat stress, and the signal was recognized and decoded by N. haitanensis calmodulin ( NhCaM ). In yeast two-hybrid assays, DnaJ, a voltage-dependent anion channel, and a bromodomain-containing protein interacted with PhCaM1 in vivo . The transcript levels of the genes encoding these proteins increased significantly in response to heat stress, but decreased upon inhibition of NhCaM1, indicating that these interacting factors were positively related to NhCaM1. Additionally, a comparative transcriptome analysis indicated that Ca 2+ signal transduction is involved in phosphatidylinositol, photosystem processes, and energy metabolism in N. haitanensis under heat stress. Our results suggest that Ca 2+ -CaM plays important roles in signal transduction in response to heat stress in N. haitanensis .