AUTHOR=Sun Yang , Wang Lijun , Pan Xuewei , Osire Tolbert , Fang Haitian , Zhang Huiling , Yang Shang-Tian , Yang Taowei , Rao Zhiming 

TITLE=Improved Prodigiosin Production by Relieving CpxR Temperature-Sensitive Inhibition

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2020.00344

DOI=10.3389/fbioe.2020.00344

ISSN=2296-4185

ABSTRACT=<p>Prodigiosin (PG) is a typical secondary metabolite mainly produced by <italic>Serratia marcescens</italic>. CpxR protein is an OmpR family transcriptional regulator in Gram-negative bacteria. Firstly, it was found that insertion mutation of <italic>cpxR</italic> in <italic>S. marcescens</italic> JNB 5-1 by a transposon Tn5G increased the production of PG. Results from the electrophoretic mobility shift assay (EMSA) indicated that CpxR could bind to the promoter of the <italic>pig</italic> gene cluster and repress the transcription levels of genes involved in PG biosynthesis in <italic>S. marcescens</italic> JNB 5-1. In the Δ<italic>cpxR</italic> mutant strain, the transcription levels of the <italic>pig</italic> gene cluster and the genes involved in the pathways of PG precursors, such as proline, pyruvate, serine, methionine, and S-adenosyl methionine, were significantly increased, hence promoting the production of PG. Subsequently, a fusion segment composed of the genes <italic>proC, serC</italic>, and <italic>metH</italic>, responsible for proline, serine, and methionine, was inserted into the <italic>cpxR</italic> gene in <italic>S. marcescens</italic> JNB 5-1. On fermentation by the resultant engineered <italic>S. marcescens</italic>, the highest PG titer reached 5.83 g/L and increased by 41.9%, relative to the parental strain. In this study, we revealed the role of CpxR in PG biosynthesis and provided an alternative strategy for the engineering of <italic>S. marcescens</italic> to enhance PG production.</p>