Genome-wide identification and analysis of HECT E3 ubiquitin ligase gene family in Saccharina japonica and a comparative analysis with five other algae

Abstract

Abstract Homologous to E6-associated protein Carboxyl Terminus (HECT) is one important family of E3 ubiquitin ligase superfamily involved in the ubiquitin-proteasome pathway. This gene family plays widely roles in the regulation of growth, development and signaling pathways in different organisms, as a specific key molecule in ubiquitin signal transduction. Large number of studies have focused on the identification and characterization of HECT E3 ligase in plants and animals, but studies in Ochrophyta, a phylogenetic lineage that is distantly related to terrestrial plants and animals, are very scarce. This study comprehensively analyzed the HECT E3 ligase gene family in algae Saccharina japonica with significant economic and ecological value. Eighteen HECT E3 ligase members were identified in S. japonica genome, and the physicochemical parameters, phylogenetic relationships, structural mechanisms, functional annotations, and gene expression of these E3 ligases were analyzed and characterized. Additionally, the HECT E3 genes were also identified from other five algae genomes. A total of 90 HECT E3 from the six algae species were used to elucidate the evolutionary relatedness of the HECT gene family in algae. The resulted phylogenetic tree revealed that the HECT family was mainly divided into six branches. Protein structure analysis revealed the conservation of the HECT domain in the entire gene family, showing the substrate binding and structure-function relationships. A large number of regulatory elements involved in stress, hormone regulation, light response, growth and development were identified in the promoter region of SjHECT E3 genes. Expression analysis indicated that members in different SjHECT gene subfamilies might play specific roles in the growth and heat stress response of S. japonica. Overall, the identification and analysis of the HECT E3 gene family in S. japonica laid the foundation for further study on the function and regulatory pathways of HECT in Ochrophyta species.