Social Interactions and Biofilm Formation in Bacillus subtilis

Međustanična je komunikacija (engl. quorum sensing, QS) oblik kooperativnog socijalnog ponašanja bakterija što se oslanja na prepoznavanje izvanstaničnih signalnih molekula. Signalna se molekula veže na receptor i inducira promjenu transkripcije gena, odgovornih za stvaranje biofilma, proizvodnju izvanstaničnih enzima i druge kooperativne značajke populacije. Svrha je ovoga rada bila dati pregled objavljenih znanstvenih radova koji se bave kooperativnim socijalnim ponašanjem bakterije Bacillus subtilis, a naročito doprinosom komunikacijskog sustava ComQXPA. Sustav QS obuhvaća četiri komponente koje su u međusobnoj interakciji: izoprenil transferazu ComQ što procesira i modificira signal, peptid ComX koji ima ulogu signala, receptor ComP i transkripcijski regulator ComA. Fosforilirani ComA kontrolira transkripciju brojnih gena, uključujući i one odgovorne za proizvodnju surfaktina te izvanstaničnog matriksa, važnog za nastajanje biofilma. Sustav ComQXPA QS ima visok stupanj genetičkog polimorfizma, što je vidljivo iz činjenice da se sojevi Bacillus subtilis mogu podijeliti u četiri skupine. Sojevi jedne skupine (ferotipa) mogu razmjenjivati signale i informacije, dok to nije moguće između različitih ferotipova. Nedavno smo pokazali da je ovaj fenomen djelomično posljedica ekološke raznolikosti sojeva, ali su moguće i alternativne hipoteze, koje daju prednost socijalnoj evoluciji. Između ostalog, sustav ComQXPA kontrolira i proizvodnju izvanstaničnog matriksa, koji se sastoji od polisaharida, proteina i nukleinskih kiselina. U ovom je radu dan pregled trenutnih spoznaja o regulaciji, strukturi, kemijskom sastavu i funkciji izvanstaničnog matriksa. Usprkos mnogim važnim nedavnim otkrićima u području regulacije formiranja biofilma B. subtilis, molekularne interakcije među komponentama matriksa i njihov utjecaj na QS i stabilnost biofilma nisu još dobro poznati, pa se u ovom radu razmatraju i moguća rješenja ovih zanimljivih pitanja.Quorum sensing (QS) is a form of cooperative social behaviour which relies on extracellular signalling molecules that elicit the QS response across many cells and controls the development of many cooperative traits including biofilm formation. The main aim of this work is to review the published work on cooperative social behaviour of Bacillus subtilis and especially its QS system ComQXPA. This QS system involves four interacting components: the signal-processing enzyme ComQ, the ComX signal, the ComP receptor and the ComA transcriptional regulator. Phosphorylated ComA controls the transcription of many genes including those responsible for the production of surfactin and extracellular matrix, essential for biofilm formation. The ComQXPA QS shows a high degree of genetic polymorphism, which manifests itself in the separation of Bacillus subtilis strains into four different communication groups (pherotypes). The information exchange is possible between members of the same pherotype but not across pherotypes. We have recently suggested that this phenomenon is at least in part driven by the ecological divergence of strains, but may also be induced by frequency-dependent selection. The ComQXPA QS system controls the production of extracellular matrix (ECM) components: polysaccharides, proteins and nucleic acids. We will address the present understanding of the ECM structure-function relationships in B. subtilis biofilms and review published results on regulation, composition and distribution of ECM components. Despite many important recent discoveries on regulation of B. subtilis biofilm development, we know little about the molecular interactions in the ECM and the role they play in the QS and stability of the biofilm. Future research needs to address these questions better

Exploring ComQXPA quorum-sensing diversity and biocontrol potential of Bacillus spp. isolates from tomato rhizoplane

Bacillus subtilis is a widespread and diverse bacterium t exhibits a remarkable intraspecific diversity of the ComQXPA quorum-sensing (QS) system. This manifests in the existence of distinct communication groups (pherotypes) that can efficiently communicate within a group, but not between groups. Similar QS diversity was also found in other bacterial species, and its ecological and evolutionary meaning is still being explored. Here we further address the ComQXPA QS diversity among isolates from the tomato rhizoplane, a natural habitat of B. subtilis, where these bacteria likely exist in their vegetative form. Because this QS system regulates production of anti-pathogenic and biofilm-inducing substances such as surfactins, knowledge on cell–cell communication of this bacterium within rhizoplane is also important from the biocontrol perspective. We confirm the presence of pherotype diversity within B. subtilis strains isolated from a rhizoplane of a single plant. We also show that B. subtilis rhizoplane isolates show a remarkable diversity of surfactin production and potential plant growth promoting traits. Finally, we discover that effects of surfactin deletion on biofilm formation can be strain specific and unexpected in the light of current knowledge on its role it this process

Classification and intracellular signaling transduction of metabotropic biogenic amine receptors

Biogenic amines are very important biologically high- active compounds. Biological effect requires their cooperation with membrane receptors, belonging mainly to metabotropic receptors. These receptors activate specific type of G proteins, which subsequently take part in intracellular signaling pathways and therefore lead to activation of metabolic and biological processes such as: glycolysis, glyconeogenesis, transcription, translation, contraction of smooth muscle of blood vessels. Knowledge of intracellular signaling and its regulation may be helpful in preparing specific therapeutic solutions to pathologies, where biogenic amines play a significant role.Aminy biogenne stanowią niezwykle ważną grupę związków o wysokiej aktywności biologicznej. Wywołanie efektu biologicznego wymaga współdziałania amin z błonowymi receptorami, w większości należącymi do receptorów metabotropowych. Receptory te uaktywniają określony rodzaj białek G, które z kolei uczestniczą w wewnątrzkomórkowej sygnalizacji prowadząc do pobudzenia zróżnicowanych procesów metabolicznych i biologicznych, m. in: glikolizy, glikogenolizy, transkrypcji, translacji, skurczu mięśni gładkich naczyń krwionośnych. Znajomość sygnalizacji wewnątrzkomórkowej oraz jej regulacji może być pomocna w opracowaniu specyficznych rozwiązań terapeutycznych patologii, w których znaczący jest udział amin biogennych