Cleavage of the signaling mucin Msb2 by the aspartyl protease Yps1 is required for MAPK activation in yeast

Signaling mucins are cell adhesion molecules that activate RAS/RHO guanosine triphosphatases and their effector mitogen-activated protein kinase (MAPK) pathways. We found that the Saccharomyces cerevisiae mucin Msb2p, which functions at the head of the Cdc42p-dependent MAPK pathway that controls filamentous growth, is processed into secreted and cell-associated forms. Cleavage of the extracellular inhibitory domain of Msb2p by the aspartyl protease Yps1p generated the active form of the protein by a mechanism incorporating cellular nutritional status. Activated Msb2p functioned through the tetraspan protein Sho1p to induce MAPK activation as well as cell polarization, which involved the Cdc42p guanine nucleotide exchange factor Cdc24p. We postulate that cleavage-dependent activation is a general feature of signaling mucins, which brings to light a novel regulatory aspect of this class of signaling adhesion molecule

Bio-inspired coating strategies for the immobilization of polymyxins to generate contact-killing surfaces

Microbial colonization of indwelling devices remains a major concern in modern healthcare. Developing approaches to prevent biomaterial-associated infections (BAI) is, therefore, in great demand. This study aimed to immobilize two antimicrobial peptides (polymyxins B and E) onto polydimethylsiloxane (PDMS) using two polydopamine (pDA)-based approaches: the conventional two-step method involving the deposition of a pDA layer to which biomolecules are immobilized, and a one-step method where peptides are dissolved together with dopamine before its polymerization. Surface characterization confirms the immobilization of polymyxins onto PDMS at a non-toxic concentration. Immobilization of polymyxins using a one-step pDA-based approach is able to prevent Pseudomonas aeruginosa adhesion and kill a significant fraction of the adherent ones. Living cells adhered to these modified surfaces exhibit the same susceptibility pattern as cells adhered to unmodified surfaces, highlighting no resistance development. Results suggest that polymyxins immobilization holds a great potential as an additional antimicrobial functionality in the design of biomaterials.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT), the strategic funding of UID/BIO/04469/2013 unit. This study was also supported by FCT and the European Community fund FEDER, through Program COMPETE, under the scope of the Projects “PTDC/SAU-SAP/113196/2009 (FCOMP-01-0124-FEDER-016012),” “RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462),” and “BioHealth—Biotechnology and Bioengineering approaches to improve health quality,” Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. The authors also acknowledge FCT for the PhD Grant of Diana Alves (SFRH/BD/78063/2011)

Bio-inspired coating strategies for the immobilization of polymyxins to generate contact-killing surfaces

Microbial colonization of indwelling devices remains a major concern in modern healthcare. Developing approaches to prevent biomaterial-associated infections (BAI) is, therefore, in great demand. This study aimed to immobilize two antimicrobial peptides (polymyxins B and E) onto polydimethylsiloxane (PDMS) using two polydopamine (pDA)-based approaches: the conventional two-step method involving the deposition of a pDA layer to which biomolecules are immobilized, and a one-step method where peptides are dissolved together with dopamine before its polymerization. Surface characterization confirms the immobilization of polymyxins onto PDMS at a non-toxic concentration. Immobilization of polymyxins using a one-step pDA-based approach is able to prevent Pseudomonas aeruginosa adhesion and kill a significant fraction of the adherent ones. Living cells adhered to these modified surfaces exhibit the same susceptibility pattern as cells adhered to unmodified surfaces, highlighting no resistance development. Results suggest that polymyxins immobilization holds a great potential as an additional antimicrobial functionality in the design of biomaterials.The authors acknowledge the Portuguese Foundation for Science and Technology (FCT), the strategic funding of UID/BIO/04469/2013 unit. This study was also supported by FCT and the European Community fund FEDER, through Program COMPETE, under the scope of the Projects “PTDC/SAU-SAP/113196/2009 (FCOMP-01-0124-FEDER-016012),” “RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462),” and “BioHealth—Biotechnology and Bioengineering approaches to improve health quality,” Ref. NORTE-07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, FEDER. The authors also acknowledge FCT for the PhD Grant of Diana Alves (SFRH/BD/78063/2011)