Reconstitution of a Biofilm Adhesin System from a Sulfate-Reducing Bacterium in Pseudomonas fluorescens.

Biofilms of the sulfate reducing bacterium (SRB) Desulfovibrio vulgaris Hildenborough (DvH) can facilitate metal corrosion in various industrial and environmental settings leading to substantial economic losses; however, the mechanisms of biofilm formation by DvH are not yet well-understood. Evidence suggests that a large adhesin, DvhA, may be contributing to biofilm formation in DvH. The dvhA gene and its neighbors encode proteins that resemble the Lap system, which regulates biofilm formation by Pseudomonas fluorescens, including a LapG-like protease DvhG and effector protein DvhD, which has key differences from the previously described LapD. By expressing the Lap-like adhesion components of DvH in P. fluorescens, our data support the model that the N-terminal fragment of the large adhesin DvhA serves as an adhesin "retention module" and is the target of the DvhG/DvhD regulatory module, thereby controlling cell-surface location of the adhesin. By heterologously expressing the DvhG/DvhD-like proteins in a P. fluorescens background lacking native regulation (ΔlapGΔlapD) we also show that cell surface regulation of the adhesin is dependent upon the intracellular levels of c-di-GMP. This study provides insight into the key players responsible for biofilm formation by DvH, thereby expanding our understanding of Lap-like systems.

An N-Terminal Retention Module Anchors the Giant Adhesin LapA of Pseudomonas fluorescens at the Cell Surface: a Novel Subfamily of Type I Secretion Systems.

LapA of Pseudomonas fluorescens Pf0-1 belongs to a diverse family of cell surface-associated bacterial adhesins that are secreted via the type I secretion system (T1SS). We previously reported that the periplasmic protease LapG cleaves the N terminus of LapA at a canonical dialanine motif to release the adhesin from the cell surface under conditions unfavorable to biofilm formation, thus decreasing biofilm formation. Here, we characterize LapA as the first type I secreted substrate that does not follow the "one-step" rule of T1SS. Rather, a novel N-terminal element, called the retention module (RM), localizes LapA at the cell surface as a secretion intermediate. Our genetic, biochemical, and molecular modeling analyses support a model wherein LapA is tethered to the cell surface through its T1SS outer membrane TolC-like pore, LapE, until LapG cleaves LapA in the periplasm. We further demonstrate that this unusual retention strategy is likely conserved among LapA-like proteins, and it reveals a new subclass of T1SS ABC transporters involved in transporting this group of surface-associated LapA-like adhesins. These studies demonstrate a novel cell surface retention strategy used throughout the Proteobacteria and highlight a previously unappreciated flexibility of function for T1SS.IMPORTANCE Bacteria have evolved multiple secretion strategies to interact with their environment. For many bacteria, the secretion of cell surface-associated adhesins is key for initiating contact with a preferred substratum to facilitate biofilm formation. Our work demonstrates that P. fluorescens uses a previously unrecognized secretion strategy to retain the giant adhesin LapA at its cell surface. Further, we identify likely LapA-like adhesins in various pathogenic and commensal proteobacteria and provide phylogenetic evidence that these adhesins are secreted by a new subclass of T1SS ABC transporters.

Vinculación del médico y enfermera de la familia con la microbrigada social / Linking of the family physician and nurse with the social microbrigada

Resumen: Se realiza un estudio descriptivo, retrospectivo del quinquenio 1990-1995, en el Consultorio 34-3, del área de salud "XX Aniversario" de Santa Clara, Villa Clara, para conocer la vinculación del trabajo del médico y la enfermera de la familia a la microbrigada social de un barrio insalubre sometido a acciones físico-constructivas y de animación social y algunos cambios introducidos por los investigadores. El análisis de los resultados se realizó mediante la aplicación de métodos cuantitativos técnicas de investigación cualitativas, arribando a las siguientes conclusiones: la creación de la microbrigada social vinculada al equipo de salud constituye el acontecimiento más relevante de la barriada en los últimos años. Se constatan cambios positivos en el estilo de vida, y en el estado de salud de la población. Las modificaciones en los riesgos sociales son el resultado del trabajo de participación comunitaria y social bajo el liderazgo del grupo profiláctico multidisciplinario

Vinculación del médico y enfermera de la familia con la microbrigada social / Linking of the family physician and nurse with the social microbrigada

Resumen: Se realiza un estudio descriptivo, retrospectivo del quinquenio 1990-1995, en el Consultorio 34-3, del área de salud "XX Aniversario" de Santa Clara, Villa Clara, para conocer la vinculación del trabajo del médico y la enfermera de la familia a la microbrigada social de un barrio insalubre sometido a acciones físico-constructivas y de animación social y algunos cambios introducidos por los investigadores. El análisis de los resultados se realizó mediante la aplicación de métodos cuantitativos técnicas de investigación cualitativas, arribando a las siguientes conclusiones: la creación de la microbrigada social vinculada al equipo de salud constituye el acontecimiento más relevante de la barriada en los últimos años. Se constatan cambios positivos en el estilo de vida, y en el estado de salud de la población. Las modificaciones en los riesgos sociales son el resultado del trabajo de participación comunitaria y social bajo el liderazgo del grupo profiláctico multidisciplinario(AU)