Staphylococci: Colonizers and Pathogens of Human Skin

Rosanna Coates; Josephine Moran; Malcolm J Horsburgh

Disclosures

Future Microbiol. 2014;9(1):75-91. 

In This Article

RNase 7

Compared with RNase 5, the antimicrobial activity of RNase 7 is considerably broader. RNase 7 is expressed and active in epithelial tissues, including the human epidermis where it is active at low concentrations across a wide temperature range. High levels of RNase 7 in healthy skin were associated with protection against infection by S. aureus.[57] Further evidence for the physiological relevance of RNase7 comes from Simanski et al. who demonstrated that antibody blocking of RNase 7 activity in skin explants impairs killing activity against S. aureus.[50] RNase 7 is cationic with an abundance of lysine residues, and exhibits ribonuclease activity.[58]

Concentration-dependent growth inhibition of S. aureus was observed in cells transformed with an RNase 7-expressing plasmid, with near-complete killing at micromolar enzyme concentrations.[58] While its antimicrobial mechanism of action is uncertain, Huang et al. credit the cationic properties of RNase 7 with its ability to pervade the bacterial membrane causing permeability.[59] Mutation and NMR analysis of the enzyme identified a flexible cluster of lysine residues integral to ribonuclease, but not antimicrobial activity.[59]

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