Víctor V Barrios-Rafael, Carlos L Ahumada-Manuel, Scherezada Orgaz-Ramírez, Jessica Nava-Galeana, Josefina Guzmán, Soledad Moreno, Víctor H Bustamante, Cinthia Núñez
{"title":"c-di-GMP效应物FleQ通过抑制黄氏固氮菌中algD的转录来控制海藻酸盐的产生。","authors":"Víctor V Barrios-Rafael, Carlos L Ahumada-Manuel, Scherezada Orgaz-Ramírez, Jessica Nava-Galeana, Josefina Guzmán, Soledad Moreno, Víctor H Bustamante, Cinthia Núñez","doi":"10.1099/mic.0.001556","DOIUrl":null,"url":null,"abstract":"<p><p>Production of the exopolysaccharide alginate by <i>Azotobacter vinelandii</i>, member of the <i>Pseudomonadaceae</i> family, is positively controlled by the second messenger c-di-GMP. This effect was solely attributed to the role of c-di-GMP in activating the alginate polymerase complex. In this study, the role of c-di-GMP in <i>algD</i> transcription, which encodes the key enzyme for alginate synthesis, was investigated. <i>algD</i> transcription correlated with artificially high or low levels of c-di-GMP. Moreover, FleQ, one of the best-characterized c-di-GMP effectors, was found to exert a negative effect on alginate production and <i>algD</i> transcription, as both increased in a Δ<i>fleQ</i> mutant relative to the wild-type strain or the Δ<i>fleQ</i>/<i>fleQ</i>+ complemented strain. Electrophoretic mobility shift assays (EMSAs) confirmed that FleQ directly binds to the regulatory region of <i>algD</i>, which was consistent with the presence of two FleQ binding sites in the vicinity of the <i>algD</i> RpoS-dependent promoter. In <i>A. vinelandii</i>, c-di-GMP is essential for the expression of alginate C-5 epimerases (AlgE1-6), which are necessary for structuring the envelope of differentiated cells, known as cysts. However, FleQ was not involved in this regulation. Collectively, our results support a model in which <i>algD</i> transcription is under the positive control of c-di-GMP, while FleQ may only partially mediate this effect. In contrast, our study revealed a FleQ-independent regulatory mechanism for the control of <i>A. vinelandii</i> encystment.</p>","PeriodicalId":49819,"journal":{"name":"Microbiology-Sgm","volume":"171 4","pages":""},"PeriodicalIF":2.6000,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12022260/pdf/","citationCount":"0","resultStr":"{\"title\":\"The c-di-GMP effector FleQ controls alginate production by repressing transcription of <i>algD</i> in <i>Azotobacter vinelandii</i>.\",\"authors\":\"Víctor V Barrios-Rafael, Carlos L Ahumada-Manuel, Scherezada Orgaz-Ramírez, Jessica Nava-Galeana, Josefina Guzmán, Soledad Moreno, Víctor H Bustamante, Cinthia Núñez\",\"doi\":\"10.1099/mic.0.001556\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Production of the exopolysaccharide alginate by <i>Azotobacter vinelandii</i>, member of the <i>Pseudomonadaceae</i> family, is positively controlled by the second messenger c-di-GMP. This effect was solely attributed to the role of c-di-GMP in activating the alginate polymerase complex. In this study, the role of c-di-GMP in <i>algD</i> transcription, which encodes the key enzyme for alginate synthesis, was investigated. <i>algD</i> transcription correlated with artificially high or low levels of c-di-GMP. Moreover, FleQ, one of the best-characterized c-di-GMP effectors, was found to exert a negative effect on alginate production and <i>algD</i> transcription, as both increased in a Δ<i>fleQ</i> mutant relative to the wild-type strain or the Δ<i>fleQ</i>/<i>fleQ</i>+ complemented strain. Electrophoretic mobility shift assays (EMSAs) confirmed that FleQ directly binds to the regulatory region of <i>algD</i>, which was consistent with the presence of two FleQ binding sites in the vicinity of the <i>algD</i> RpoS-dependent promoter. In <i>A. vinelandii</i>, c-di-GMP is essential for the expression of alginate C-5 epimerases (AlgE1-6), which are necessary for structuring the envelope of differentiated cells, known as cysts. However, FleQ was not involved in this regulation. Collectively, our results support a model in which <i>algD</i> transcription is under the positive control of c-di-GMP, while FleQ may only partially mediate this effect. 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The c-di-GMP effector FleQ controls alginate production by repressing transcription of algD in Azotobacter vinelandii.
Production of the exopolysaccharide alginate by Azotobacter vinelandii, member of the Pseudomonadaceae family, is positively controlled by the second messenger c-di-GMP. This effect was solely attributed to the role of c-di-GMP in activating the alginate polymerase complex. In this study, the role of c-di-GMP in algD transcription, which encodes the key enzyme for alginate synthesis, was investigated. algD transcription correlated with artificially high or low levels of c-di-GMP. Moreover, FleQ, one of the best-characterized c-di-GMP effectors, was found to exert a negative effect on alginate production and algD transcription, as both increased in a ΔfleQ mutant relative to the wild-type strain or the ΔfleQ/fleQ+ complemented strain. Electrophoretic mobility shift assays (EMSAs) confirmed that FleQ directly binds to the regulatory region of algD, which was consistent with the presence of two FleQ binding sites in the vicinity of the algD RpoS-dependent promoter. In A. vinelandii, c-di-GMP is essential for the expression of alginate C-5 epimerases (AlgE1-6), which are necessary for structuring the envelope of differentiated cells, known as cysts. However, FleQ was not involved in this regulation. Collectively, our results support a model in which algD transcription is under the positive control of c-di-GMP, while FleQ may only partially mediate this effect. In contrast, our study revealed a FleQ-independent regulatory mechanism for the control of A. vinelandii encystment.
期刊介绍:
We publish high-quality original research on bacteria, fungi, protists, archaea, algae, parasites and other microscopic life forms.
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