TABLE 5.

Targets related to the proper assembly and performance of essential virulence factors across the peptidoglycan

Target	Role(s)	Species	Effect(s) of target disruption	Reference(s)
Secretion systems
ExeAB	PGN binding and remodeling to allow secretin ExeD insertion and T2SS multimerization, assembly, and performance	A. hydrophila	Loss of aerolysin secretion and of lipase activity in culture supernatants	107–109
HpaH	A lytic transglycosylase required for T3SS assembly	X. campestris	Attenuated for pathogenicity in a plant model	116
HrpH, HopP1, and HopAJ1	Lytic transglycosylases coregulated by the T3SS to allow the translocation of effector proteins into plant cells	P. syringae	Attenuated for pathogenicity in a tobacco plant model	115
L0045	A putative lytic transglycosylase critical for T3SS	Enterohemorrhagic E. coli	T3SS impairment	114
EtgA	A lytic transglycosylase required for T3SS assembly	Enterohemorrhagic E. coli	Attenuated for T3SS activity and red blood cell lysis	112, 113
MltE	A lytic transglycosylase required for T6SS assembly	Enteroaggregative E. coli	Loss of T6SS function and, consequently, cytotoxicity impairment	119
VirB operon	A transglycosylase with activity that allows the formation of the T pilus, a subassembly of the vir T4SS	A. tumefaciens	Loss of tumorigenesis in a Kalanchoe daigremontiana plant model	117
AtlA	A transglycosylase with activity that allows the assembly of T4SS	N. gonorrhoeae	Loss of allolysis in E. coli	118
TagX	A l,d-endopeptidase required for T6SS assembly	Acinetobacter spp.	Loss of T6SS function and, therefore, cytotoxicity impairment; a decrease in bacterial killing capacity in E. coli coculture assays	120
PtlE	A peptidoglycanase responsible for local PGN degradation during Ptl secretion complex assembly	B. pertussis	Decreased release of pertussis toxin, leading to reduced effects (such as focal adhesion loss) on CHO cells	121
Flagellum
FlgJ	A β-N-acetylglucosaminidase required for degradation of PGN to allow assembly of flagella	S. enterica and other beta- and gammaproteobacteria	Nonmotile phenotype	122
Sltf	A lytic transglycosylase interacting with FlgJ to allow the penetration of the nascent flagellar structure across the PGN	Rhodobacter sphaeroides	Nonmotile phenotype	123, 124
MltD	A lytic transglycosylase contributing to maturation of PGN for the proper anchoring and functionality of the flagellar motor	H. pylori	Nonmotile phenotype	125