Biosynthesis of LPS components occurs in the cytoplasm and at the cytoplasmic side of the inner membrane. The core-lipid A moiety is first flipped by the essential ABC transporter MsbA across the IM ligated with the O-antigen and then transported across the periplasm by a transenvelope device, the Lpt protein machinery, composed in E. coli by seven essential proteins. At the IM, the LptBFG complex constitutes an ABC transporter that provides the energy for LPS transport. LptC is a small bitopic protein that resides in the IM and interacts with the LptBFG complex and with the periplasmic protein LptA. LptA is thought to transfer LPS to the LptDE protein complex of the OM. Thus, LptA is the periplasmic protein that connects the IM Lpt components to the OM LPS translocon, which ensures the assembly of LPS at the cell surface. The Lpt machinery appears to operate as a single device as depletion of any Lpt component leads to common phenotypes that includes the appearance of an anomalous LPS form decorated by repeating units of colanic acid, and in such depleted strains the majority of de novo synthesised LPS accumulates in a novel membrane fraction with higher density than the IM. The process by which Dasatinib hydrophobic LPS is transported across the periplasm to the cell surface is not fully understood. The current model postulates that the Lpt proteins, through homologous domains interactions, create a transenvelope bridge that connects IM and OM, thus forming a continuous channel through which LPS is moved to the cell surface. The OM is an essential structure for bacterial survival and the first site of interaction with the mammalian host ; mutants defective in OM biogenesis typically display alterations of the OM permeability barrier properties. The crucial role of this structure is highlighted by the fact that in E. coli at least five different pathways constitute signaling systems that detect and respond to alterations of the bacterial envelope. These pathways regulate expression of complementary functions whose discrete contributions are integrated to mount a full adaptive response. In fungi, relatively few molecules are universally considered as MAMPs, such as chitin, with its variants like chitosan, ethyleneinducing xylanase, b-glucans, necrosis- and ethylene-inducing peptide 1 -like proteins and ergosterol. Some of these molecules are not only produced by fungi, such as b-glucans and Nep1-lke proteins, which can be found in oomycetes and bacteria. Recently, proteins belonging to a new fungal protein family, the “cerato-platanin family”, have provided more and more experimental evidence of their MAMP activity. Cerato-platanin proteins are produced by plant pathogenic and non-pathogenic fungi, both ascomycetes and basidiomycetes. Concerning the primary role of these proteins, recent results suggest that they are mono-domain expansin-like proteins localised in the cell wall and involved in the hyphal growth and development. Moreover, a role in the fungus-plant interaction has also been reported. When CPPs are applied on host and non-host plants, they induce defence-related responses and resistance against pathogens.