Objective Characteristics and roles played in response to abiotic stresses of the heat shock transcription factor HSF in Cordyceps cateniannulata were studied.

Method Based on the transcriptome database, CcHSF759 was cloned using the local BLAST method. Bioinformatics analyses including sequence characterization, phylogenetic analysis, domain prediction, and tertiary structure modeling were conducted on the cloned gene with the expressions under various imposed stresses detected by RT-qPCR.

Result The successfully cloned CcHSF759 had a CDS of 1005 bp and encoded 334 amino acids with a molecular weight of 36.52 kDa and an isoelectric point of 6.05. Phylogenetically, it closely related to C. javanica, Beauveria asiatica, and B. bassiana. The protein contained typical N-terminal HSF, middle coiled-coil domains, and two low-complexity regions at the C-terminus. Its tertiary structure was composed mainly of random coils and α-helices. Under high or low temperature, high osmotic pressure, cell wall interference, and oxidative stress, CcHSF759, as well as CcHSP78, CcHSP90, and CcHSP100, exhibited differential stress-specific expressions. CcHSF759 and CcHSP90 were consistently inversely correlated to the treatments of high temperature, hyperosmotic condition, and interference to cell wall integrity. Whereas other HSP members displayed variations in their reaction to the abiotic stresses.

Conclusion CcHSF759 might participate in the transcriptional response and displayed expressions to abiotic stresses different from other HSP proteins in C. cateniannulata. Further study to decipher the regulatory functions and molecular mechanism associated with the heat shock transcription factors is in order.