When Ribonucleases Come into Play in Pathogens: A Survey of Gram-Positive Bacteria

Table 1

Ribonucleases: mechanism of action and known virulence targets/phenotypes in Gram-positive pathogens.

Ribonuclease (name of the gene)	Mechanism of action	Result	ncRNA or protein partner	Targets in virulence/phenotype/comments	Organism	Refrence
PNPase (PNP)	3′ to 5′ exoribonucleolytic	Repression		Essential for cold stress response/affects global mRNA turnover	S. aureus	[4]
RNase P (rnpA)	Endoribonucleolytic	Repression		Affects expression of a large set of virulence factors/rnpA depleted cells exhibited attenuated virulence in a mouse infection model	S. aureus	[75]
RNase III (rnc)	dsRNA specific endoribonucleolytic	Repression	RNAIII	Represses multiple mRNA targets encoding virulence factors (spa, coa. SA1000, rot), indirectly activates levels of secreted proteins (Efb)/Δrnc strain was attenuated in a mouse infection model	S. aureus	[44, 71, 72, 97]
RNase Y (rny)	endoribonucleolytic	Repression		Affects expression of virulence factors through agr or independently/affects virulence in silkworm and mouse models	S. aureus	[81, 83]
RNase Y	Endoribonucleolytic	Repression		Affects expression of several virulence factors/affects virulence in silkworm and mouse models	S. pyogenes	[81, 82]
RNases J1/J2 (rnjA/rnjB)	Endoribonucleolytic, 5′-3′ exoribonucleolytic	Repression		Affect bulk mRNA decay and expression of multiple virulence factors	S. pyogenes	[78–80]
RNase J2	Endoribonucleolytic, 5′-3′ exoribonucleolytic	Activation		ebp operon (pilus proteins)/rnjB is essential for biofilm formation	E. faecalis	[68]
Unknown		Activation	FasX	Stabilizes ska mRNA encoding streptokinase	S. pyogenes	[70]
Unknown		Activation	VR-RNA	Activates translation of colA mRNA encoding toxin collagenase	C. perfringens	[90]
Unknown		Repression	LhrA and Hfq	Represses the synthesis of ChiA protein (chitinase)	L. monocytogenes	[100, 101]
Csn1/ RNase III	Endoribonucleolytic/dsRNA-specific endoribonucleolytic	Repression	tracrRNA	Targets foreign invading DNA such as plasmid and phages	S. pyogenes, Listeria innocua, Streptococcus mutans, Streptococcus thermophilus	[102]
Catalytic ribozyme	Alternative splicing	Activation	Riboswitch with bound c-di-GMP	Activates the translation of a putative virulence gene	C. difficile	[109, 110]
PemK	Endoribonucleolytic	Repression		Affects global RNA decay	B. anthracis	[124]
MazF, Txe	Endoribonucleolytic	Repression		Localizes with vancomycin resistance genes, confers plasmid stabilization	enterococci	[125, 126]
MazF	Endoribonucleolytic	Repression		Cleaves several mRNAs (sraP, spa and hla) encoding virulence factors, and possibly other mRNAs	S. aureus	[128–131, 133]
MazF, VapC	Endoribonucleolytic	Repression		Several TA modules are upregulated during hypoxia and infection of macrophages	M. tuberculosis	[113, 135, 136]