RESUMO
In many bacteria, the stabilities and functions of small regulatory RNAs (sRNAs) that act by base pairing with target RNAs most often are dependent on Hfq or ProQ/FinO-domain proteins, two classes of RNA chaperone proteins. However, while all bacteria appear to have sRNAs, many have neither Hfq nor ProQ/FinO-domain proteins raising the question of whether another factor might act as an sRNA chaperone in these organisms. Several recent studies have reported that KH domain proteins, such as KhpA and KhpB, bind sRNAs. Here we describe what is known about the distribution, structures, RNA-binding properties, and physiologic roles of KhpA and KhpB and discuss evidence for and against these proteins serving as sRNAs chaperones.
Assuntos
Proteínas de Bactérias/metabolismo , Chaperonas Moleculares/metabolismo , RNA Bacteriano/metabolismo , Pequeno RNA não Traduzido/metabolismo , Proteínas de Ligação a RNA/metabolismo , Proteínas de Bactérias/genética , Fator Proteico 1 do Hospedeiro/genética , Fator Proteico 1 do Hospedeiro/metabolismo , Modelos Moleculares , Chaperonas Moleculares/genética , Domínios Proteicos , RNA Bacteriano/genética , Pequeno RNA não Traduzido/genética , Proteínas de Ligação a RNA/genéticaRESUMO
Periodontitis (PD) is a chronic inflammatory disease of periodontal tissues caused by pathogenic microorganisms and characterized by disruption of the tooth-supporting structures. Conventional drug administration pathways in periodontal disease treatment have many drawbacks such as poor biodistribution, low selectivity of the therapeutic effect, burst release of the drug, and damage to healthy cells. To overcome this limitation, controlled drug delivery systems have been developed as a potential method to address oral infectious disease ailments. The use of drug delivery devices proves to be an excellent auxiliary method in improving the quality and effectiveness in periodontitis treatment, which includes inaccessible periodontal pockets. This review explores the current state of knowledge regarding the applications of various polymer-based delivery systems such as hydrogels, liposomes, micro-, and nanoparticles in the treatment of chronic periodontal disease. Furthermore, to present a more comprehensive understanding of the difficulties concerning the treatment of PD, a brief description of the mechanism and development of the disease is outlined.
RESUMO
The regulation of gene expression by small RNAs in Escherichia coli depends on RNA binding proteins Hfq and ProQ, which bind mostly distinct RNA pools. To understand how ProQ discriminates between RNA substrates, we compared its binding to six different RNA molecules. Full-length ProQ bound all six RNAs similarly, while the isolated N-terminal FinO domain (NTD) of ProQ specifically recognized RNAs with Rho-independent terminators. Analysis of malM 3'-UTR mutants showed that tight RNA binding by the ProQ NTD required a terminator hairpin of at least 2 bp preceding an 3' oligoU tail of at least four uridine residues. Substitution of an A-rich sequence on the 5' side of the terminator to uridines strengthened the binding of several ProQ-specific RNAs to the Hfq protein, but not to the ProQ NTD. Substitution of the motif in the malM-3' and cspE-3' RNAs also conferred the ability to bind Hfq in E. coli cells, as measured using a three-hybrid assay. In summary, these data suggest that the ProQ NTD specifically recognizes 3' intrinsic terminators of RNA substrates, and that the discrimination between RNA ligands by E. coli ProQ and Hfq depends both on positive determinants for binding to ProQ and negative determinants against binding to Hfq.
