The secreted catalase PaCATB modulates lifespan of Podospora anserina under oxidative stress

One of the most studied aging theories is the `free radical theory' which established a connection between Reactive Oxygen Species (ROS) and aging. ROS can be derived from various endo- and exogenous sources. Accumulation of ROS mediated damages contribute to biological aging. Aerobic organisms contain catalases for enzymatic decomposition of hydrogen peroxide, a common ROS. In the fungal aging model P. anserina one of the five predicted catalases is secreted (PaCATB).

To unravel the function of PaCATB in respect to aging, we constructed and analysed P. anserina strains with an altered PaCATB abundance. Under standard growth conditions, the deletion strain ΔPaCatB and the over-expressing strain PaCatB_OEx exhibit a wild-type like phenotype and lifespan. However, when cultivated on media containing hydrogen peroxide to apply exogenous oxidative stress, the ΔPaCatB strain shows a reduced resistance against this stressor while PaCatB_OEx is found to have an increased hydrogen peroxide tolerance. In addition, when grown under oxidative stress conditions, lifespan was reduced in the ΔPaCatB strain and prolonged in the PaCatB_OEx strain. Overall, our results indicate that PaCATB plays a major role for maintaining viability and lifespan during oxidative stress. This ability appears to be relevant under natural conditions, when P. anserina strains grow together with other microorganisms which themselves might secrete hydrogen peroxide in order to survive competitive growth conditions.