23 research outputs found
Transcription and Translation Products of the Cytolysin Gene psm-mec on the Mobile Genetic Element SCCmec Regulate Staphylococcus aureus Virulence
The F region downstream of the mecI gene in the SCCmec element in hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) contains two bidirectionally overlapping open reading frames (ORFs), the fudoh ORF and the psm-mec ORF. The psm-mec ORF encodes a cytolysin, phenol-soluble modulin (PSM)-mec. Transformation of the F region into the Newman strain, which is a methicillin-sensitive S. aureus (MSSA) strain, or into the MW2 (USA400) and FRP3757 (USA300) strains, which are community-acquired MRSA (CA-MRSA) strains that lack the F region, attenuated their virulence in a mouse systemic infection model. Introducing the F region to these strains suppressed colony-spreading activity and PSMΞ± production, and promoted biofilm formation. By producing mutations into the psm-mec ORF, we revealed that (i) both the transcription and translation products of the psm-mec ORF suppressed colony-spreading activity and promoted biofilm formation; and (ii) the transcription product of the psm-mec ORF, but not its translation product, decreased PSMΞ± production. These findings suggest that both the psm-mec transcript, acting as a regulatory RNA, and the PSM-mec protein encoded by the gene on the mobile genetic element SCCmec regulate the virulence of Staphylococcus aureus
Photooxidation of ethylene over Cu-modified and unmodified silica
Silica catalyzes photooxidation of ethylene to carbon dioxide and modification of copper on silica
results in the lower reaction rate and partial production of ethylene oxide. The reaction does not proceed
by the light irradiation through a color filter (Ξ»>280 nm). ESR measurement indicates that radical oxygen
species assignable T-shape Si β O3β can be produced on silica by UV irradiation at 77 K. The same species
are also found on silica modified with copper by UV irradiation while the quantity is smaller. When silica
and silica modified with copper are UV-irradiated in presence of oxygen and ethylene at 77 K, formation of
methyl radicals is confirmed only on silica while ethyl radicals are observed with both samples. We suggest
that copper stabilizes C2 species and prevents cleavage of C β C bonding