Isolation of a non-genomic origin fluoroquinolone responsive regulatory element using a combinatorial bioengineering approach

Complete identity and expression of StfZ, the cis-antisense RNA to the mRNA of the cell division gene ftsZ, in Escherichia coli

Bacteria regulate FtsZ protein levels through transcriptional and translational mechanisms for proper cell division. A cis-antisense RNA, StfZ, produced from the ftsA-ftsZ intergenic region, was proposed to regulate FtsZ level in Escherichia coli. However, its structural identity remained unknown. In this study, we determined the complete sequence of StfZ and identified the isoforms and its promoters. We find that under native physiological conditions, StfZ is expressed at a 1:6 ratio of StfZ:ftsZ mRNA at all growth phases from three promoters as three isoforms of 366, 474, and 552 nt RNAs. Overexpression of StfZ reduces FtsZ protein level, increases cell length, and blocks cell division without affecting the ftsZ mRNA stability. We did not find differential expression of StfZ under the stress conditions of heat shock, cold shock, or oxidative stress, or at any growth phase. These data indicated that the cis-encoded StfZ antisense RNA to ftsZ mRNA may be involved in the fine tuning of ftsZ mRNA levels available for translation as per the growth-phase-specific requirement at all phases of growth and cell division.

Electrostatic Surface Potential of Macrophages Correlates with Their Functional Phenotype

Macrophages exist in various functional phenotypes, which could be identified by specific surface molecules. Previous studies have shown that modulation of surface charges could alter the phagocytic function of macrophages. In this study, we show that activation of both human peripheral blood monocyte and THP-1-derived macrophages with lipopolysaccharide (LPS) or IL-1β resulted in a significant decrease in the zeta potential compared to freshly isolated monocytes and unstimulated macrophages. Interestingly, interaction with bacteria significantly increased the zeta potential of such cells irrespective of activation conditions. Similarly, IFNγ-treated pro-inflammatory macrophages showed lesser negative zeta potential compared to untreated control. A moderate reduction was also seen in IL-4-treated anti-inflammatory subtype. Additionally, in an LPS-induced systemic inflammation model, bone marrow cells isolated after 2 h of LPS injection showed significant reduction in zeta potential compared to naïve cells. Furthermore, electrostatic potential measurement of surface proteins associated with pro-inflammatory and anti-inflammatory macrophages, using in silico modeling under physiological and protonation conditions, showed that the average electrostatic potential of pro-inflammatory type surface proteins was less negative than anti-inflammatory subtype. These data suggest that the expression of different protein molecules on macrophages under different environments may contribute to the zeta potential and that this quick and low-cost technique could be used in monitoring macrophage functional phenotypes.