RESUMEN
The two archaea Ignicoccus hospitalis and Nanoarchaeum equitans form a unique intimate association, the character of which is not yet fully understood. Electron microscopic investigations show that at least two modes of cell-cell interactions exist: (i) the two cells are interconnected via thin fibres; and (ii) the two cell surfaces are in direct contact with each other. In order to shed further light on the molecules involved, we isolated a protein complex, by using detergent-induced solubilization of cell envelopes, followed by a combination of chromatography steps. Analysis by MS and comparison with databases revealed that this fraction contained two dominant proteins, representing the respective major envelope proteins of the two archaea. In addition, a considerable set of membrane proteins is specifically associated with these proteins. They are now the focus of further biochemical and ultrastructural investigations.
Asunto(s)
Proteínas Arqueales/metabolismo , Nanoarchaeota/citología , Nanoarchaeota/metabolismo , Proteínas Arqueales/aislamiento & purificación , Adhesión Celular , Cromatografía en Gel , Técnicas de Cocultivo , Proteínas de la Membrana/aislamiento & purificación , Nanoarchaeota/ultraestructura , Estabilidad Proteica , SolubilidadRESUMEN
The universality of ribonuclease P (RNase P), the ribonucleoprotein essential for transfer RNA (tRNA) 5' maturation, is challenged in the archaeon Nanoarchaeum equitans. Neither extensive computational analysis of the genome nor biochemical tests in cell extracts revealed the existence of this enzyme. Here we show that the conserved placement of its tRNA gene promoters allows the synthesis of leaderless tRNAs, whose presence was verified by the observation of 5' triphosphorylated mature tRNA species. Initiation of tRNA gene transcription requires a purine, which coincides with the finding that tRNAs with a cytosine in position 1 display unusually extended 5' termini with an extra purine residue. These tRNAs were shown to be substrates for their cognate aminoacyl-tRNA synthetases. These findings demonstrate how nature can cope with the loss of the universal and supposedly ancient RNase P through genomic rearrangement at tRNA genes under the pressure of genome condensation.
Asunto(s)
Evolución Molecular , Genes Arqueales/genética , Nanoarchaeota/genética , Regiones Promotoras Genéticas/genética , ARN de Archaea/genética , ARN de Transferencia/genética , Ribonucleasa P/deficiencia , Aminoacil-ARNt Sintetasas/metabolismo , Aminoacilación , Secuencia de Bases , Eliminación de Gen , Modelos Biológicos , Datos de Secuencia Molecular , Nanoarchaeota/citología , Nanoarchaeota/enzimología , Fosforilación , ARN de Archaea/metabolismo , ARN de Transferencia/metabolismo , Ribonucleasa P/metabolismo , Especificidad por Sustrato , Transcripción Genética/genéticaRESUMEN
Nanobacteria or living nanovesicles are of great interest to the scientific community because of their dual nature: on the one hand, they appear as primal biosystems originating life; on the other hand, they can cause severe diseases. Their survival as well as their pathogenic potential is apparently linked to a self-synthesized protein-based slime, rich in calcium and phosphate (when available). Here, we provide challenging evidence for the occurrence of nanobacteria in the stratosphere, reflecting a possibly primordial provenance of the slime. An analysis of the slime's biological functions may lead to novel strategies suitable to block adhesion modalities in modern bacterial populations.
