波尔菲迪乌姆紫球藻（Porphyridium purpureum）藻红蛋白基因（phycoerythrin gene）及格拉西拉里奥普斯莱曼尼藻（Gracilariopsis lemaneiformis）肌动蛋白基因（actin gene）核心启动子区域的鉴定及其活性验证

Abstract

PE243 and Actin373 promoters were superior to CaMV 35S promoter. • Two efficient promoter elements can be used for genetic manipulation in both Porphyridium purpureum and Gracilariopsis lemaneiformis . • Droplet-entrapping microfluidic cell-sorter(DREM cell)was applicable for screening of positive Porphyridium purpureum cells. • Porphyridium purpureum may be utilized as a preliminary platform for evaluating the functionality of genetic transformation elements designed for Gracilariopsis lemaneiformis . This study identified the core promoter regions of the phycoerythrin (PE) gene from Porphyridium purpureum and the actin (Actin) gene from Gracilariopsis lemaneiformis through deletion analysis, and evaluated their activity in promoting protein expression in both prokaryotic and eukaryotic systems. Initially, the 2000 bp upstream sequence of the PE gene and the 2030 bp upstream sequence of the Actin gene were cloned as full-length promoter sequences. Following bioinformatic prediction of their cis-regulatory elements, 5′-end deletion fragments with varying lengths were isolated. Promoter test vectors, utilizing green or blue fluorescent protein genes as reporters, were constructed and transformed into Escherichia coli , P. purpureum , and G. lemaneiformis, respectively to validate promoter activity. The results demonstrated that the PE243 and Actin373 promoter fragments exhibited high activity in both prokaryotic and eukaryotic systems. These fragments showed stronger and more sustained driving capability than the commonly used CaMV 35S promoter in both P. purpureum and G. lemaneiformis , characterized by their short sequence length and high efficiency. Furthermore, this study validated the feasibility of using P. purpureum as a test platform for genetic transformation elements of G. lemaneiformis , and also confirmed DREM cell sorting as a novel method for screening targeted P. purpureum . The two efficient short-sequence promoter elements