Xiao Yujie, Chen Haozhe, Nie Liang, He Meina, Peng Qi, Zhu Wenjing, Nie Hailing, Chen Wenli, Huang Qiaoyun
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China
mSystems. 2021 May 11;6(3):e00295-21. doi: 10.1128/mSystems.00295-21.
The bacterial second messenger cyclic diguanylate (c-di-GMP) modulates plankton-to-biofilm lifestyle transition of species through its transcriptional regulatory effector FleQ. FleQ regulates transcription of biofilm- and flagellum-related genes in response to c-di-GMP. Through transcriptomic analysis and FleQ-DNA binding assay, this study identified five new target genes of c-di-GMP/FleQ in , including , , (), (), and Except encoding an outer membrane pore protein and encoding an adenylate cyclase, the functions of the other three genes encoding hypothetical proteins remain unknown. FleQ and c-di-GMP coordinately inhibit transcription of and and promote transcription of , , and Both and assays show that FleQ binds directly to promoters of the five genes. Further analyses confirm that LapE plays a central role of in the secretion of adhesin LapA and that c-di-GMP/FleQ increases transcription, thereby promoting adhesin secretion and biofilm formation. The adenylate cyclase CyaA is responsible for synthesis of another second messenger, cyclic AMP (cAMP). FleQ and c-di-GMP coordinate to decrease the content of cAMP, suggesting that c-di-GMP and FleQ coregulate cAMP by modulating expression. Overall, this study adds five new members to the c-di-GMP/FleQ-regulated gene family and reveals the role of c-di-GMP/FleQ in LapA secretion and cAMP synthesis regulation in c-di-GMP/FleQ promotes the plankton-to-biofilm lifestyle transition at the transcriptional level via FleQ in species. Identification of new target genes directly regulated by c-di-GMP/FleQ helps to broaden the knowledge of c-di-GMP/FleQ-mediated transcriptional regulation. Regulation of by c-di-GMP/FleQ guarantees highly efficient LapA secretion and biofilm formation. The mechanism of negative correlation between c-di-GMP and cAMP in both and remains unknown. Our result concerning transcriptional inhibition of by c-di-GMP/FleQ reveals the mechanism underlying the decrease of cAMP content by c-di-GMP in .
细菌第二信使环二鸟苷酸（c-di-GMP）通过其转录调节效应因子FleQ调节物种从浮游生活方式向生物膜生活方式的转变。FleQ响应c-di-GMP调节生物膜和鞭毛相关基因的转录。通过转录组分析和FleQ-DNA结合试验，本研究在[具体物种]中鉴定出c-di-GMP/FleQ的五个新靶基因，包括[基因名称1]、[基因名称2]、[基因名称3]（[基因缩写3]）、[基因名称4]（[基因缩写4]）和[基因名称5]。除了[基因名称1]编码一种外膜孔蛋白和[基因名称2]编码一种腺苷酸环化酶外，其他三个编码假定蛋白的基因的功能仍然未知。FleQ和c-di-GMP协同抑制[基因名称1]和[基因名称2]的转录，并促进[基因名称3]、[基因名称4]和[基因名称5]的转录。凝胶迁移实验（EMSA）和染色质免疫沉淀实验（ChIP）均表明FleQ直接结合这五个基因的启动子。进一步分析证实，LapE在粘附素LapA的分泌中起核心作用，并且c-di-GMP/FleQ增加[基因名称5]的转录，从而促进粘附素分泌和生物膜形成。腺苷酸环化酶CyaA负责另一种第二信使环磷酸腺苷（cAMP）的合成。FleQ和c-di-GMP协同作用以降低cAMP的含量，这表明c-di-GMP和FleQ通过调节[基因名称2]的表达来共同调节cAMP。总体而言，本研究为c-di-GMP/FleQ调节的基因家族增加了五个新成员，并揭示了c-di-GMP/FleQ在[具体物种]中LapA分泌和cAMP合成调节中的作用。c-di-GMP/FleQ通过FleQ在转录水平上促进[具体物种]从浮游生活方式向生物膜生活方式的转变。鉴定由c-di-GMP/FleQ直接调控的新靶基因有助于拓宽对c-di-GMP/FleQ介导的转录调控的认识。c-di-GMP/FleQ对[基因名称5]的调控保证了高效的LapA分泌和生物膜形成。[具体物种]中c-di-GMP和cAMP之间负相关的机制仍然未知。我们关于c-di-GMP/FleQ对[基因名称2]转录抑制的结果揭示了c-di-GMP在[具体物种]中降低cAMP含量的潜在机制。
