The universal stress protein UspA is a small cytoplasmic bacterial protein whose expression is enhanced several-fold when cellular viability is challenged with heat shock, nutrient starvation, stress agents which arrest cell growth, or DNA-damaging agents. UspA enhances the rate of cell survival during prolonged exposure to such conditions, suggesting that it asserts a general "stress endurance" activity. In general, these proteins form dimers and have domains for nucleotide binding activity. The crystal structure of Haemophilus influenzae UspA reveals an asymmetric dimer with a tertiary alpha/beta fold similar to that of the Methanococcus jannaschii MJ0577 protein, but unlike MJ0577, it lacks ATP-binding activity.
Jiyao W et al.(2023). "The conserved domain database in 2023.",