Effects of dual deletion ofglnRandmtrAon expression of nitrogen metabolism genes inStreptomyces venezuelae

Abstract

Summary GlnR activates nitrogen metabolism genes under nitrogen‐limited conditions, whereas MtrA represses these genes under nutrient‐rich conditions in Streptomyces. In this study, we compared the transcription patterns of nitrogen metabolism genes in a double deletion mutant (ΔmtrA‐glnR) lacking both mtrA and glnR and in mutants lacking either mtrA (ΔmtrA) or glnR (ΔglnR). The nitrogen metabolism genes were expressed similarly in ΔmtrA‐glnR and ΔglnR under both nitrogen‐limited and nutrient‐rich conditions, with patterns distinctly different from that of ΔmtrA, suggesting a decisive role for GlnR in the control of nitrogen metabolism genes and further suggesting that regulation of these genes by MtrA is GlnR‐dependent. MtrA and GlnR utilize the same binding sites upstream of nitrogen metabolism genes, and we showed stronger in vivo binding of MtrA to these sites under nutrient‐rich conditions and of GlnR under nitrogen‐limited conditions, consistent with the higher levels of MtrA or GlnR under those respective conditions. In addition, we showed that both mtrA and glnR are self‐regulated. Our study provides new insights into the regulation of nitrogen metabolism genes in Streptomyces.

Comparative Proteomic Analysis of Transcriptional and Regulatory Proteins Abundances in S. lividans and S. coelicolor Suggests a Link between Various Stresses and Antibiotic Production

“…This cluster includes 11 regulatory proteins ( Figure 9 ): The response regulator MtrA/SCO3013 of the TCS SCO3013/SCO3012 (MtrB, HK) which, as PhoP, regulates both N and Pi metabolism. MtrA negatively auto-regulates its own expression and that of GlnR/SCO4159 [ 180 , 181 ]. MtrA represses, in condition of N proficiency, the genes that are activated by GlnR/SCO4159 in condition of N limitation [ 181 ].…”

“…MtrA negatively auto-regulates its own expression and that of GlnR/SCO4159 [ 180 , 181 ]. MtrA represses, in condition of N proficiency, the genes that are activated by GlnR/SCO4159 in condition of N limitation [ 181 ]. MtrA has a direct, but either positive or negative, impact on the expression of PhoRP and of other genes of Pi metabolism depending on the composition of the growth medium [ 182 ].…”

“…An important outcome of this paper is that the regulatory proteins GlnRI/SCO4159/SLI_4154 (cluster G) [ 70 , 86 , 173 ] and MtrA/SCO3013/SLI_3005 (cluster H) [ 180 , 181 ], involved in the positive and negative control of nitrogen metabolism, respectively, were poorly abundant in SC compared to SL and this was correlated with the very low abundance of proteins involved in nitrogen up-take and assimilation in SC compared to SL , as reported in Lejeune et al [ 9 ]. Consequently, SC most likely suffers from severe nitrogen stress.…”

“…Consistently, proteins whose expression is under the positive control of GlnR such as the ammonium transporter AmtB/SCO5583, the glutamine synthases GSI/SCO2198/GlnA and GSII/SCO2210, as well as the regulator SCO2958/NnaR and its regulatory targets essential for nitrate and nitrite assimilation [ 70 , 86 , 173 ] were far more abundant in Pi proficiency than in Pi limitation in SL but not in SC (Figure 8 of [ 9 ]). In contrast, the regulator MtrA, which represses the expression of glnRI and that of the genes under its positive control [ 181 ], is clearly more abundant in Pi limitation than in Pi proficiency in SL but not in SC . This study thus revealed that GlnRI that positively controls the expression of genes involved in N up-take and assimilation is more abundant in Pi proficiency than in Pi limitation, whereas MtrA, which negatively controls the expression of these genes, is more abundant in Pi limitation than in Pi proficiency, in SL .…”

Characterization of a pleiotropic regulator MtrA in Streptomyces avermitilis controlling avermectin production and morphological differentiation

“…MtrA binds more strongly to nitrogen metabolism genes under nitrogen-rich conditions, while GlnR binds more strongly to these genes under nitrogen-limited conditions. Additionally, both MtrA and GlnR possess the ability to regulate their own gene expression [ 9 ].…”