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Cyclic dimeric GMP (c-di-GMP) is an important biofilm regulator that allosterically activates enzymes of exopolysaccharide biosynthesis. Proteobacterial genomes usually encode multiple GGDEF domain-containing diguanylate cyclases responsible for c-di-GMP synthesis. In contrast, only one conserved GGDEF domain protein, GdpS (for GGDEF domain protein from Staphylococcus), and a second protein with a highly modified GGDEF domain, GdpP, are present in the sequenced staphylococcal genomes. Here, we investigated the role of GdpS in biofilm formation in Staphylococcus epidermidis. Inactivation of gdpS impaired biofilm formation in medium supplemented with NaCI under static and flow-cell conditions, whereas gdpS overexpression complemented the mutation and enhanced wild-type biofilm development. GdpS increased production of the icaADBC-encoded exopolysaccharide, poly-N-acetyl-glucosamine, by elevating icaADBC mRNA levels. Unexpectedly, c-di-GMP synthesis was found to be irrelevant for the ability of GdpS to elevate icaADBC expression. Mutagenesis of the GGEEF motif essential for diguanylate cyclase activity did not impair GdpS, and the N-terminal fragment of GdpS lacking the GGDEF domain partially complemented the gdpS mutation. Furthermore, heterologous diguanylate cyclases expressed in traus failed to complement the gdpS mutation, and the purified GGDEF domain from GdpS possessed no diguanylate cyclase activity in vitro. The gdpS gene from Staphylococcus aureus exhibited similar characteristics to its S. epidermidis orthoiog, suggesting that the GdpS-mediated signal transduction is conserved in staphylococci. Therefore, GdpS affects biofilm formation through a novel c-di-GMP-independent mechanism involving increased icaADBC mRNA levels and exopolysaccharide biosynthesis. Our data raise the possibility that staphylococci cannot synthesize c-di-GMP and have only remnants of a c-di-GMP signaling pathway.

A method is presented for the rapid detection and characterization of trace amounts of peptides secreted from microorganisms, including pheromones, virulence factors, and quorum-sensing peptides. The procedure, based on targeted multistage MS, uses a novel matrix-assisted laser desorption/ionization-ion trap mass spectrometer to overcome limitations of current MS methods (limited dynamic range, signal suppression effects, and chemical noise) that impair observation of low abundance peptides from complex biological matrixes. Here, secreted peptides that are hypothesized to be present in the supernatant, but that may not be sufficiently abundant to be observed in single-stage mass spectra, are subjected to multistage MS. Highly specific fragmentation signatures enable unambiguous identification of the peptides of interest and differentiation of the signals from the background. As examples, we demonstrate the rapid (

Research has been conducted on Staphylococcus aureus C (sub)30 carotene synthase CrtM and Erwinia uredovora C (sub)40 carotene cynthase CrtB. These synthases have been swapped into their C (sub)40 and C (sub)30 biosynthetic pathways expressed in Escherichia coli and their function has been evaluated and discussed.

Research has been conducted on Staphylococcus carnosus display system. The autrhors report the use of genetically engineered domains to test the functionality of the display system for the target cell enrichment from the background cell excess via the use of flow cytometry.

Research has been conducted on Staphylococcus aureus replication initiation gene orf245. The authors demonstrate that this gene can maintain heterologous replicons and that it represents a class of active partitioning systems enhancing plasmid segregational stability via a single protein-encoding gene.

Research has been conducted on Staphylococcus auerus quinone oxidoreductase gene. The characterization of this gene has been carried out, and the results demonstrate that staphylococcal membrane-bound quinone oxidoreductase's activity is similar to that of zeta-Crystallin.

Research has been conducted on Staphylococcus aureus gene regulation. Results demonstrate that repressor of toxins, Rot, is a global regulator which regulates virulence gene transcription.