AUTHOR=Qiu Hulin , Chang Xiaoyu , Luo Yan , Shen Fengfei , Yin Aiguo , Miao Tingting , Li Ying , Xiao Yunyi , Hai Jinping , Xu Bo 

TITLE=Regulation of Nir gene in Lactobacillus plantarum WU14 mediated by GlnR

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.983485

DOI=10.3389/fmicb.2022.983485

ISSN=1664-302X

ABSTRACT=<p>Nitrogen (N) is an essential element in the biosynthesis of key cellular components, such as proteins and nucleic acids, in all living organisms. Nitrite, as a form of nitrogen utilization, is the main nutrient for microbial growth. However, nitrite is a potential carcinogen that combines with secondary amines, which are breakdown products of proteins, to produce N-nitroso compounds that are strongly carcinogenic. Nitrite reductase (<italic>Nir</italic>) produced by microorganisms can reduce nitrite. Binding of <italic>GlnR</italic> to the promoter of nitrogen metabolism gene can regulate the expression of <italic>Nir</italic> operon. In this study, nitrite-resistant <italic>Lactobacillus plantarum</italic> WU14 was isolated from Pickles and its protease <italic>Nir</italic> was analyzed. <italic>GlnR</italic>-mediated regulation of <italic>L. plantarum</italic> WU14 <italic>Nir</italic> gene was investigated in this study. New <italic>GlnR</italic> and <italic>Nir</italic> genes were obtained from <italic>L. plantarum</italic> WU14. The regulation effect of <italic>GlnR</italic> on <italic>Nir</italic> gene was examined by gel block test, yeast two-hybrid system, bacterial single hybrid system and qRT-RCR. Detailed analysis showed that <italic>GlnR</italic> ound to the <italic>Nir</italic> promoter region and interacted with <italic>Nir</italic> at low nitrite concentrations, positively regulating the expression of <italic>NIR</italic>. However, the transcription levels of <italic>GlnR</italic> and <italic>Nir</italic> decreased gradually with increasing nitrite concentration. The results of this study improve our understanding of the function of the <italic>Nir</italic> operon regulatory system and serve as the ground for further study of the signal transduction pathway in lactic acid bacteria.</p>