Lawrence Berkeley National Laboratory

The crystal structure of the hypothetical protein MPN555 from Mycoplasma pneumoniae (gi pbar 1673958) has been determined to a resolution of 2.8 Angstrom using anomalous diffraction data at the Se peak wavelength. Structure determination revealed a mostly alpha-helical protein with a three-lobed shape. The three lobes or fingers delineate a central binding groove and additional grooves between lobes 1 and 3, and between lobes 2 and 3. For one of the molecules in the asymmetric unit, the central binding pocket was filled with a peptide from the uncleaved N-terminal affinity tag. The MPN555 structure has structural homology to two bacterial chaperone proteins, SurA and trigger factor from Escherichia coli. The structural data and the homology to other chaperone for MPN555.