YbbR domains are widespread throughout eubacteria and are expressed as monomeric units, linked in tandem repeats or cotranslated with other domains. Though the precise role of these domains remains undefined, the location of the tetratandem YbbR domain coding ybbR gene in the Bacillus subtilis glmM operon and its previous identification as a substrate for a surfactin-type phosphopantetheinyl transferase suggests a role in cell growth, division and virulence. To further characterize the YbbR domains, structures of two of the four domains from the YbbR protein of Desulfitobacterium hafniense DCB-2, were solved by solution nuclear magnetic resonance and x-ray crystallography. The structures show the domains to have nearly identical topologies despite a minimal amino acid identity (23%). The topology, which has just a single representative in the structural database, is dominated by ?-strands, roughly following a “figure 8” pattern with some strands coiling around the domain perimeter and others crossing the center. The homologous domain in the structural database is the C-terminal domain of a stress-responsive bacterial CTC protein. Based on these models a structurally-guided amino acid alignment identifies features of the YbbR domains that are not evident from naïve amino acid alignments. A structurally conserved cisPro residue was identified in both domains, though the immediate vicinities surrounding this residue differed between the two models. The conservation and location of this cisPro plus anchoring Val residues suggests this motif may be significant to protein function.
Revised: March 21, 2011 |
Published: February 1, 2011
Citation
Barb A.W., J.R. Cort, J. Seetharaman, S. Lew, H. Lee, T. Acton, and R. Xiao, et al. 2011.Structures of Domains I and IV from YbbR are representative of a widely distributed protein family.Protein Science 20, no. 2:396-405. PNWD-SA-9037. doi:10.1002/pro.571