AUTHOR=Li Xiefei , Fan Xiankang , Shi Zihang , Xu Jue , Cao Yingying , Zhang Tao , Pan Daodong 

TITLE=AI-2E Family Transporter Protein in Lactobacillus acidophilus Exhibits AI-2 Exporter Activity and Relate With Intestinal Juice Resistance of the Strain

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.908145

DOI=10.3389/fmicb.2022.908145

ISSN=1664-302X

ABSTRACT=<p>The function of the autoinducer-2 exporters (AI-2E) family transporter protein of <italic>Lactobacillus acidophilus</italic> is still unclear. The phylogenetic analysis was used to analyze the relationship between the AI-2E protein of the <italic>L. acidophilus</italic> CICC 6074 strain and other AI-2E family members. <italic>Escherichia coli</italic> KNabc strain was used to verify whether the protein has Na<sup>+</sup> (Li<sup>+</sup>)/H<sup>+</sup> antiporter activity. The AI-2E protein overexpression strain was constructed by using the pMG36e expression vector, and the overexpression efficiency was determined by real-time quantitative PCR. The vitality and AI-2 activity of <italic>L. acidophilus</italic> CICC 6074 strains were determined. The results showed that the AI-2E protein of <italic>Lactobacillus</italic> formed a single branch on the phylogenetic tree and was closer to the AI-2E family members whose function was AI-2 exporter group I. The expression of AI-2E protein in the <italic>E. coli</italic> KNabc strain did not recover the resistance of the bacteria to the saline environment. Overexpression of AI-2E protein in <italic>L. acidophilus</italic> CICC 6074 could promote the AI-2 secretion of <italic>L. acidophilus</italic> CICC 6074 strain and enhance their survival ability in intestinal juice.</p>