Transcriptomic analyses unravel differential expression of genes involved in the N-glycosylation pathway of Phaeodactylum tricornutum ecotypes

ABSTRACT

Most of the biologics are glycoproteins. It is well-established that N-glycans harboured by proteins are involved in the protein half-life, bioactivity and immunogenicity. Currently, most of the biologics are produced in mammalian cells. However, microalgae emerged as a cheaper alternative biofactory. Among them, the diatom Phaeodactylum tricornutum benefits from numerous advantages and has been successfully used to produce biologics such as SARS-COV2 RBD and functional monoclonal antibodies (mAbs). These mAbs have been demonstrated to be glycosylated with oligomannosides that are similar to the mammalian ones and that result from processing steps occurring in the ER and the early Golgi apparatus. Surprisingly, these oligomannosides represent the major N-glycans population even if the diatom possesses glycoenzymes potentially involved in the biosynthesis of complex-type N-glycans in the Golgi apparatus. Therefore, it is essential to characterize the regulation of the P. tricornutum protein N-glycosylation pathway as well as the expression level of genes involved in the N-glycosylation of proteins. In the present work, we performed RNA-Seq analyses on different ecotypes of P. tricornutum and decode the differential expression of genes involved in the protein N-glycosylation pathway.