Decreased expression of LRA4, a key gene involved in rhamnose metabolism, caused up-regulated expression of the genes in this pathway and autophagy in Pichia pastoris

摘要

In a previous study, we developed Pichia pastoris GS115m, an engineered strain with decreased expression of one key gene, LRA4 , in rhamnose metabolism. P. pastoris GS115m/ LacB was subsequently constructed via introducing a β-galactosidase gene, LacB , under the control of rhamnose-inducible P _( LRA3 ) into P. pastoris GS115m. P. pastoris GS115m/ LacB greatly improved recombinant protein production relative to the parental strain ( P . pastoris GS115/ LacB ). In the present study, transcriptomes of P . pastoris GS115m/ LacB and P . pastoris GS115/ LacB grown in YPR medium were analyzed. P . pastoris GS115m/ LacB was found to suffer from the mild carbon source starvation. To attenuate the starvation stress, P . pastoris GS115m/ LacB attempted to enhance rhamnose metabolism by elevating the transcription levels of rhamnose-utilization genes LRA1 - 3 and RhaR . The transcription level of LacB under the control of P _( LRA3 ) thereby increased, resulting in the improved production of recombinant protein in P . pastoris GS115m/ LacB . It was also revealed that P . pastoris GS115m/ LacB cells coped with carbon starvation mostly via autophagy.