To control the growth of microorganisms on its surface, human skin produces and releases certain peptides and proteins, including cathelicidin LL-37 and beta-defensins.  It is known that several members of both the RNase A superfamily (RNases 1, 4, 5, and 7) and the desquamin class of RNases are expressed in human skin, and that human skin RNases as a whole specifically cleave RNA substrates at single-stranded C-rich regions.  The author proposes that human skin RNases provide dual protection against invading bacteria:  They may bind to and disrupt bacterial membranes, and/or may enter bacteria and disrupt their transcription process.  Human skin RNase 7 may be an important defense mechanism against microorganisms that do not use Rho-dependent transcriptional terminators (i.e., their RNAs may not have an unstructured C-rich region), as it can rapidly inactivate these organisms through membrane disruption.  For microorganisms that do use Rho-dependent transcriptional terminators, the mechanism(s) by which RNases on human skin gain entrance into the bacterial cell to exert their ribonuclease activity is currently unknown.  The author hypothesizes that the RNases may bind to a specific lipoprotein associated with the bacterial membrane leading to the processing and internalization of the membrane protein along with the skin RNases.<br/>

Human skin RNases offer dual protection against invading bacteria

255th National Meeting (2018)

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