title: Structure and Function of AmtR in Mycobacterium smegmatis: Implications for Post-Transcriptional Regulation of Urea Metabolism through a Small Antisense RNA

authors: Petridis, Michael

subjects: Science & Technology

abstract: Soil-dwelling bacteria of the phylum actinomycetes generally harbor either GlnR or AmtR as a global regulator of nitrogen metabolism. Mycobacterium smegmatis harbors both of these canonical regulators; GlnR regulates the expression of key genes involved in nitrogen metabolism, while the function and signal transduction pathway of AmtR in M. smegmatis remains largely unknown. Here, we report the structure and function of the M. smegmatis AmtR and describe the role of AmtR in the regulation of nitrogen metabolism in response to nitrogen availability. To determine the function of AmtR in M. smegmatis, we performed genome-wide expression profiling comparing the wild-type versus an ΔamtR mutant and identified significant changes in the expression of 11 genes, including an operon involved in urea degradation. An AmtR consensus-binding motif (CTGTC-N4-GACAG) was identified in the promoter region of this operon, and ligand-independent, high-affinity AmtR binding was validated by both electrophoretic mobility shift assays and surface plasmon resonance measurements. We confirmed the transcription of a cis-encoded small RNA complementary to the gene encoding AmtR under nitrogen excess, and we propose a post-transcriptional regulatory mechanism for AmtR. The three-dimensional X-ray structure of AmtR at 2.0 Å revealed an overall TetR-like dimeric structure, and the alignment of the M. smegmatis AmtR and Corynebacterium glutamicum AmtR regulatory domains showed poor structural conservation, providing a potential explanation for the lack of M.smegmatisAmtRinteractionwith the adenylylated PII protein. Taken together, our data suggest an AmtR (repressor)/GlnR (activator) competitive binding mechanism for transcriptional regulation of urea metabolism that is controlled by a cis-encoded small antisense RNA.

text: Structure and Function of AmtR in Mycobacterium smegmatis: Implications for Post-Transcriptional Regulation of Urea Metabolism through a Small Antisense RNA Soil-dwelling bacteria of the phylum actinomycetes generally harbor either GlnR or AmtR as a global regulator of nitrogen metabolism. Mycobacterium smegmatis harbors both of these canonical regulators; GlnR regulates the expression of key genes involved in nitrogen metabolism, while the function and signal transduction pathway of AmtR in M. smegmatis remains largely unknown. Here, we report the structure and function of the M. smegmatis AmtR and describe the role of AmtR in the regulation of nitrogen metabolism in response to nitrogen availability. To determine the function of AmtR in M. smegmatis, we performed genome-wide expression profiling comparing the wild-type versus an ΔamtR mutant and identified significant changes in the expression of 11 genes, including an operon involved in urea degradation. An AmtR consensus-binding motif (CTGTC-N4-GACAG) was identified in the promoter region of this operon, and ligand-independent, high-affinity AmtR binding was validated by both electrophoretic mobility shift assays and surface plasmon resonance measurements. We confirmed the transcription of a cis-encoded small RNA complementary to the gene encoding AmtR under nitrogen excess, and we propose a post-transcriptional regulatory mechanism for AmtR. The three-dimensional X-ray structure of AmtR at 2.0 Å revealed an overall TetR-like dimeric structure, and the alignment of the M. smegmatis AmtR and Corynebacterium glutamicum AmtR regulatory domains showed poor structural conservation, providing a potential explanation for the lack of M.smegmatisAmtRinteractionwith the adenylylated PII protein. Taken together, our data suggest an AmtR (repressor)/GlnR (activator) competitive binding mechanism for transcriptional regulation of urea metabolism that is controlled by a cis-encoded small antisense RNA.

year: 2016-10-23

title: The rise of the fake reference

authors: Gibbons, Stephanie

abstract: This presentation discusses the risk of fake reference.

text: The rise of the fake reference This presentation discusses the risk of fake reference.

year: 2020

title: Interface of gender and culture

authors: Tamasese, Kiwi

subjects: Maori

abstract: I greet you in the soothing waters of the Pacific. The birth waters of Hawai’i to the North, island of the dream time, and Aotearoa, to the south. Papua New Guinea to the West and Marquesas to the East.  These islands are the gathering places of the world’s largest Continent, the Pacific. We of this continent know that her birth waters are our connection.  We also know that she is woman identified. It is no surprise therefore that from Hawai’i to the north to Aotearoa in the south the positioning of women in each of these societies bears a different story to that of the women of the continent of Europe.  This reality lived out in Hawai’i means women shared with men the ultimate leadership of peoples.  This location of women power is named Kuhinanui. Many remarkable women of Hawai’i occupied this position.  From times of peace throughout to the first clash with imposed new culture, women of Hawai’i led, bled, struggled, defied and kept the kukui of self belief burning. Genealogically Hawai’i is connected to her other sisters throughout the Pacific.  The story of Kuhinanui Liliuokalani is poignant.

text: Interface of gender and culture I greet you in the soothing waters of the Pacific. The birth waters of Hawai’i to the North, island of the dream time, and Aotearoa, to the south. Papua New Guinea to the West and Marquesas to the East.  These islands are the gathering places of the world’s largest Continent, the Pacific. We of this continent know that her birth waters are our connection.  We also know that she is woman identified. It is no surprise therefore that from Hawai’i to the north to Aotearoa in the south the positioning of women in each of these societies bears a different story to that of the women of the continent of Europe.  This reality lived out in Hawai’i means women shared with men the ultimate leadership of peoples.  This location of women power is named Kuhinanui. Many remarkable women of Hawai’i occupied this position.  From times of peace throughout to the first clash with imposed new culture, women of Hawai’i led, bled, struggled, defied and kept the kukui of self belief burning. Genealogically Hawai’i is connected to her other sisters throughout the Pacific.  The story of Kuhinanui Liliuokalani is poignant.

year: 1993