universal stress protein (USP) and similar proteins
The universal stress protein (USP) is a small cytoplasmic bacterial protein whose expression is enhanced when the cell is exposed to stress agents. USP enhances the rate of cell survival during prolonged exposure to such conditions, and may provide a general "stress endurance" activity. The crystal structure of Haemophilus influenzae Usp reveals an alpha/beta fold similar to that of the Methanococcus jannaschii MJ0577 protein, which binds ATP, although USP lacks ATP-binding activity.