Protein domain family PF06855 (DUF1250) is a family of small domains of unknown function found only in bacteria, and mostly in the order Bacillales and Lactobacillales. Here we describe the solution NMR or X-ray crystal structures of three representatives of this domain family, MW0776 and MW1311 from Staphyloccocus aureus and yozE from Bacillus subtilis. All three proteins adopt a four-helix motif similar to sterile alpha motif (SAM) domains. Phylogenetic analysis classifies MW1311 and yozE as functionally equivalent proteins of the UPF0346 family of unknown function, but excludes MW0776, which likely has a different biological function. Our structural characterization of the three domains supports this separation of function. The structures of MW0776, MW1311, and yozE constitute the first structural representatives from this protein domain family.
Bibliographical noteFunding Information:
Schwarnof for access to beamline X4A at Brookhaven National Laboratory. The NESG expression vectors SR391-21.2, ZR218-21.1, and ZR215-21.1 have been deposited in the PSI Materials Repository (http://psimr.asu.edu/). This research was supported by the Protein Structure Initiative of the US National Institutes of Health, grants U54 GM074958 and U54 GM094597.
- SAM domain
- Solution NMR
- Structural genomics
- X-ray crystal structure