Role ofBurkholderia pseudomalleiSigma N2 in Amino Acids Utilization and in Regulation of Catalase E Expression at the Transcriptional Level

Abstract

Burkholderia pseudomallei is the causative agent of melioidosis. The complete genome sequences of this pathogen have been revealed, which explain some pathogenic mechanisms. In various hostile conditions, for example, during nitrogen and amino acid starvation, bacteria can utilize alternative sigma factors such as RpoS and RpoN to modulate genes expression for their adaptation and survival. In this study, we demonstrate that mutagenesis of rpoN2, which lies on chromosome 2 of B. pseudomallei and encodes a homologue of the sigma factor RpoN, did not alter nitrogen and amino acid utilization of the bacterium. However, introduction of B. pseudomallei rpoN2 into E. coli strain deficient for rpoN restored the ability to utilize amino acids. Moreover, comparative partial proteomic analysis of the B. pseudomallei wild type and its rpoN2 isogenic mutant was performed to elucidate its amino acids utilization property which was comparable to its function found in the complementation assay. By contrast, the rpoN2 mutant exhibited decreased katE expression at the transcriptional and translational levels. Our finding indicates that B. pseudomallei RpoN2 is involved in a specific function in the regulation of catalase E expression.

Effect of temperature on Burkholderia pseudomallei growth, proteomic changes, motility and resistance to stress environments

“…katG and katE expression in B . pseudomallei has also been reported to be regulated by rpoS and oxyR 38 , whereas katE expression is regulated by rpoN2 39 in response to several stress conditions, such as nutritional starvation and oxidative stress. Further studies are required to investigate the effect of temperature on the expression and roles of these regulators.…”

Burkholderia pseudomalleiAdaptation for Survival in Stressful Conditions

“…Members of the σ 70 family are responsible for the expression of all essential genes, while members of the σ 54 family are mostly involved in nitrogen metabolism-associated genes. B. pseudomallei contains several σ factors, including RpoC ( σ C) [ 57 ], RpoN ( σ N) [ 58 ], RpoE ( σ E) [ 30 ], and RpoS ( σ S) [ 34 ]. RpoE and RpoS are members of the σ 70 family which play an important role in response to extracellular stress [ 55 ].…”

RpoN1 and RpoN2 play different regulatory roles in virulence traits, flagellar biosynthesis, and basal metabolism in Xanthomonas campestris

“…However, BCAAs are the primary precursors for the synthesis of BCFAs (Zhu et al , 2005). RpoN also affects amino acid utilization and carbohydrate metabolism (Stevens et al , 2010; Diep et al , 2015; Hayrapetyan et al , 2015). Therefore, we speculate that rpoN1 directly regulates the biosynthesis of amino acids and basal metabolism to affect BCFA and DSF synthesis.…”

“…RpoN also affects the growth, virulence, motility, and biofilm formation of bacteria (Hao et al , 2013; Hayrapetyan et al , 2015; Ray et al , 2015). In addition, RpoN can affect the assembly of bacterial flagella (Yang et al , 2009; Schulz et al , 2012), quorum sensing (QS) (Cai et al , 2015), amino acid utilization, the regulation of catalase expression at the transcriptional level (Diep et al , 2015), and carbohydrate metabolism (Stevens et al , 2010; Hayrapetyan et al , 2015).…”

“…Analysis of the complete genome sequences of several microorganisms has shown that the rpoN gene (encoding the σ 54 factor) is widely distributed among bacteria (Studholme et al , 2000; Studholme and Buck, 2000a, 2000b; Dombrecht et al , 2002; Studholme and Dixon, 2003). A few organisms have two copies of rpoN , such as Ralstonia solanacearum (Ray et al , 2015), Burkholderia pseudomallei (Diep et al , 2015), Bradyrhizobium japonicum (Kullik et al , 1991), and X. campestris (Yang et al , 2009). In B. japonicum , these copies are highly similar and functionally interchangeable (Kullik et al , 1991).…”