The universal stress protein UspA Swiss:P28242 [1] is a small cytoplasmic bacterial protein whose expression is enhanced when the cell is exposed to stress agents. UspA 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 UspA [3] reveals an alpha/beta fold similar to that of the Methanococcus jannaschii MJ0577 protein, which binds ATP [2], though UspA lacks ATP-binding activity.

1: Expression and role of the universal stress protein, UspA, of Escherichia coli during growth arrest. Nystrom T, Neidhardt FC; Mol Microbiol 1994;11:537-544. PMID:8152377

2: Structure-based assignment of the biochemical function of a hypothetical protein: a test case of structural genomics. Zarembinski TI, Hung LW, Mueller-Dieckmann HJ, Kim KK, Yokota H, Kim R, Kim SH; Proc Natl Acad Sci U S A 1998;95:15189-15193. PMID:9860944

3: Structure of the universal stress protein of Haemophilus influenzae. Sousa MC, McKay DB; Structure (Camb) 2001;9:1135-1141. PMID:11738040