Identification and functional characterization of a potential l-Homoserine exporter in Corynebacterium glutamicum

Exporter protein systems play a crucial role in the efficient production of valuable chemicals. However, the lack of active exporters significantly limits the application of industrial bio-based production, making the identification and utilization of novel exporters highly important. In this study, we discovered a novel l-Homoserine exporter, Cg0701, in Corynebacterium glutamicum through homology analysis. First, tolerance assays revealed that the cg0701 overexpression strain (CgH-2) exhibited a 10.45% increase in cell growth compared to the control when cultivated with 30 g/L-Homoserine. Additionally, export assays demonstrated that the l-Homoserine export capacity of CgH-2 increased by approximately 30%. Furthermore, genomic overexpression of cg0701 in an l-Homoserine-producing chassis also enhanced both tolerance and export activity. As a result, the recombinant strain CgH-11 produced 10.79 g/L-Homoserine in shake flask cultures and 48.72 g/L in a 5 L fermenter, representing improvements of 19.89% and 24.44%, respectively. In summary, our results indicate that Cg0701 is a novel l-Homoserine exporter in C. glutamicum, enriching our understanding of amino acid export systems and providing a valuable target for the construction of l-Homoserine microbial cell factories.