Non-surgical periodontal treatment with Er:YAG laser may be an alternative treatment for reduction and control of the proliferation of microorganisms in persistent periodontitis.

No abstract

The evolutionarily conserved factor eIF5A is the only protein known to undergo hypusination, a unique posttranslational modi¢cation triggered by deoxyhypusine synthase (Dys1). Although eIF5A is essential for cell viability, the function of this putative translation initiation factor is still obscure. To identify eIF5A-binding proteins that could clarify its function, we screened a two-hybrid library and identi¢ed two eIF-5A partners in S. cerevisiae: Dys1 and the protein encoded by the gene YJR070C, named Lia1 (Ligand of eIF5A). The interactions were con¢rmed by GST pulldown. Mapping binding sites for these proteins revealed that both eIF5A domains can bind to Dys1, whereas the C-terminal domain is su⁄cient to bind Lia1. We demonstrate for the ¢rst time in vivo that the N-terminal K K-helix of Dys1 can modulate enzyme activity by inhibiting eIF5A interaction. We suggest that this inhibition be abrogated in the cell when hypusinated and functional eIF5A is required. ß

The eukaryotic translation initiation factor 2 (eIF2) binds the methionyl-initiator tRNA in a GTP-dependent mode. This complex associates with the 40 S ribosomal particle, which then, with the aid of other factors, binds to the 5' end of the mRNA and migrates to the first AUG codon, where eIF5 promotes GTP hydrolysis, followed by the formation of the 80 S ribosome. Here we provide a comparative sequence analysis of the beta subunit of eIF2 and its archaeal counterpart (aIF2beta). aIF2beta differs from eIF2beta in not possessing an N-terminal extension implicated in binding RNA, eIF5 and eIF2B. The remaining sequences are highly conserved, and are shared with eIF5. Previously isolated mutations in the yeast eIF2beta, which allow initiation of translation at UUG codons due to the uncovering of an intrinsic GTPase activity in eIF2, involve residues that are conserved in aIF2beta, but not in eIF5. We show that the sequence of eIF2beta homologous to aIF2beta is sufficient for binding eIF2gamma, the only subunit with which it interacts, and comprises, at the most, 78 residues. eIF5 does not interact with eIF2gamma, despite its similarity with eIF2beta, probably because of a gap in homology in this region. These observations have implications for the evolution of the mechanism of translation initiation.