smegmatis (which was taken as a reference point to calculate fold change for all the strains) (Figure 4B).
In MSP1 glnA1 expression in low and high nitrogen conditions was up-regulated ~ 42 and ~ 15 fold respectively. The glnA1 expression in MSFP in high nitrogen was ~ 6 fold less than expression in low nitrogen while the same was only ~ 3 fold in MSP1. In case of MSP2, the expression of glnA1 gene was comparable in both low and high nitrogen conditions. In case of M. bovis, the expression of glnA1 was also ~ 36 fold up-regulated in low nitrogen conditions as compared to ~ 6.2 fold in high nitrogen conditions. Hence it was observed that in the strains, MSFP and M. bovis, where both the promoters P1 and P2 were present upstream to glnA1, the difference in the gene expression
levels PRN1371 mw in low and high nitrogen conditions were significantly higher as compared to the difference in expression levels in GSK126 mw strains having single promoter. It was concluded that deletion of any one of the two promoters decreased the stringent regulation of glnA1 gene at the transcriptional level. GS specific activity and expression in response to nitrogen limitation and excess Response selleckchem to nitrogen availability for GS enzyme was studied by measuring cellular GS activity by γ-glutamyl transferase assay . Exponential phase culture of MSFP, MSP1, MSP2, wild type M. smegmatis and M. bovis was harvested and cell pellet of 10 ml culture was further used for determining intracellular GS activity. Upon exposure to the nitrogen limiting conditions, the cellular GS activity in M. bovis, MSFP, MSP1 and MSP2 was 9.16, 12, 4.4 and 5 times higher than the high nitrogen condition respectively. Intracellular GS activity for all strains grown in high nitrogen condition was much less as compared to the activity in low nitrogen conditions (Figure 5B). Intracellular GS specific activity in MSP2 strain was 1 U/mg in low nitrogen and 0.2 U/mg in high nitrogen condition which was much less as compared to GS activity in MSFP and
MSP1 strain. The GS activity in extracellular fraction followed the same trend in all strains (Figure 5B). Western blotting of the intracellular protein fraction was done by using anti-GS antibodies (Figure 5A). Fluorometholone Acetate It was observed that in all strains the GS expression was higher in low nitrogen condition than high nitrogen condition. Although it was observed from western blotting result that the amount of GS in low nitrogen condition of MSP2 was very less but the activity of the enzyme was relatively higher than the activity of the enzyme in high nitrogen conditions of all the strains. This is in accordance with earlier findings that in high nitrogen conditions GlnE protein adenylylates the GS protein at a conserved tyrosine residue and hence, the enzyme becomes inactive.