Structure of a UPF0150-family protein fromThermus thermophilusHB8

Abstract

TTHA0281 is a hypothetical protein from Thermus thermophilus HB8 that belongs to an uncharacterized protein family, UPF0150, in the Pfam database and to COG1598 in the National Center for Biotechnology Information Database of Clusters of Orthologous Groups. The X-ray crystal structure of the protein was determined by a multiple-wavelength anomalous dispersion technique and was refined at 1.9 A resolution to a final R factor of 18.5%. The TTHA0281 monomer adopts an alpha-beta-beta-beta-alpha fold and forms a homotetramer. Based on the properties and functions of structural homologues of the TTHA0281 monomer, the TTHA0281 protein is speculated to be involved in RNA metabolism, including RNA binding and cleavage.

Crystal structure of uncharacterized protein TTHA1756 from Thermus thermophilus HB8: Structural variety in UPF0150 family proteins

“…We searched for structural homologs of TTHA1756 using the DALI server 18. Representative hits with a root mean square deviation (RMSD) of less than 3 Å for more than 40 paired C α atoms were TTHA1013 hypothetical protein19 (PDB code: 1WV8, Z‐score = 5.1, RMSD = 2.9 Å), TTHA0281 hypothetical protein7 (PDB code: 2DSY, Z‐score = 4.4, RMSD = 2.5 Å), dsRBD20 (PDB code: 1DI2, Z‐score = 3.9, RMSD = 2.8 Å), and the integrase fragment21 (PDB code: 2BB8, Z‐score = 3.0, RMSD = 1.8 Å). Based on its structural similarity, TTHA1756 constitutes a member of the dsRBD‐like fold family in the Structural Classification of Proteins database 22.…”

“…On the other hand, TTHA0281, a member of the UPF0150 family,3 forms a tetramer with a back‐to‐back association of two dimers, that is, AB and CD [Fig. 1(F)] 7. The dimer assembly of TTHA0281 is totally different from that of TTHA1756 [Fig.…”

“…The dimer assembly of TTHA0281 is totally different from that of TTHA1756 [Fig. 1(F)], and is mediated by the N‐terminal α0 helices 7. When the TTHA0281 monomer is superimposed on the TTHA1756 dimer [Fig.…”

“…We previously reported the crystal structure of TTHA0281. 7 In this study, we have solved the crystal structure of the TTHA1756 protein, another UPF0150 family protein from T. thermophilus HB8. Compared with structural homologs, we found that the UPF0150 protein family has two types of quaternary structure with a doublestranded RNA-binding domain (dsRBD) as a common fold, and a less-conserved region among the family proteins probably contributes to the structural variety.…”

“…1(A)]. We previously reported the crystal structure of TTHA0281 7. In this study, we have solved the crystal structure of the TTHA1756 protein, another UPF0150 family protein from T. thermophilus HB8.…”