| Research Abstract |
We found ObgE (previously known as YhbZ) in Escherichia coli, is homologue of Obg in B. subtillis. It carries conserved GTPase activity. We have shown that ObgE is essential for E. coli growth because ObgE is required for successful chromosome partition^1. How ObgE works is still unclear.
By proteome analysis of an obgE mutant using the RFHR 2-D PAGE method, we have found that the position of three spots of 30S ribosomal proteins, S6, S18 and S21 were changed on the sample grown under the non-permissive condition of the obgE mutant. In the wild type cell, S6 and S18 are modified post-translationally by RimK and RimI proteins with the addition of Glutamic acid residues to the C-terminals, and the acetylation of Alanine residue to the N-terminals, respectively. Under ObgE defective conditions, the spot of S6 protein shifted to the acidic side of the gel, which implies that more Glutamic acid residues were added to the C-terminals of the S6 protein than usual. Also a new spot of non-acetylated S18 protein appeared, which was confirmed by MALDI-TOFMS analysis, and the signal of the S21 spot was weakened. Furthermore, we found that the maturation of 16S RNA from pre-16S RNA was also inhibited under the ObgE defective conditions.
Since all three ribosomal proteins (S6, S18 and S21) are known to bind to the central region of 16S RNA, this data suggests that the assembly of the 30S ribosome is affected by obgE defective conditions.
1) Kobayashi, G., Moriya S., and Wada, C. (2001) Mol Microbiol., 41, 1037-1052.
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