Intracellular localization of sirtuin and cell length analysis of Lactobacillus paracasei suggest possible role of sirtuin in cell division and cell shape regulation.

Sirtuin has been associated in prolonging lifespan of different model organisms. It has been shown to have an enzymatic activity of NAD+ -dependent protein deacetylation targeting acetylated proteins. To determine targets and possible roles of sirtuin (LpSirA) in the Lactobacillus paracasei BL23, deletion (ΔsirA), sirtuin overexpressor (highsirA) and GFP fusion (highsirA-Venus) strains were generated, and microscopic localization and cell length analysis were done. Microscopic analysis revealed localization of LpSirA at cell division plates, at cell poles and all throughout the cell length in a spiral manner. Cell length analysis revealed that 46.9% of the ΔsirA cells were observed to be shorter (<2 μm), whereas 12.6% of the highsirA cells were observed to be longer (>4 μm) in comparison with the wild-type with only 17.1% short cells and 5.3% long cells. Our results suggest that sirtuin may have an essential role in cell division and cell shape regulation.