MRSA strains are resistant to b-lactam antibiotics because they have acquired one of several allotypes of a mobile genetic element, the SCCmec cassette, which includes the mecA gene encoding the low-affinity penicillin-binding protein PBP2a; this transpeptidase, which forms a functional complex with PBP2, allows peptidoglycan synthesis to continue after b-lactam-mediated acylation of native, membrane-localized PBPs. Staphylococcal peptidoglycan synthesis is highly regulated and the CMassociated FtsZ-anchored biosynthetic machinery which in MRSA includes functional PBP2/2a complexes, is located predominantly at the division septum, facilitating orderly equatorial division in orthogonal planes. In methicillin-susceptible staphylococci, but not in MRSA. Growth of MRSA in the presence of ECg elicits delocalization of PBP2 but not FtsZ even in the absence of the b-lactam agent oxacillin, providing strong evidence that ECg sensitizes MRSA strains by disrupting the septal peptidoglycan machinery following intercalation into the CM. In contrast to the zwitterionic and/or neutral surface charge of PC or PE bilayers, the staphylococcal CM is comprised of a complex asymmetric mixture of a number of lipids with different charge characteristics, predominantly phosphatidylglycerol, PG modified by enzymatic transfer of a lysine residue and cardiolipin. No information is currently available on the capacity of ECg or other galloyl catechins to intercalate into the staphylococcal CM save that ECg Cenerimod distributes predominantly but not exclusively to the membrane fraction of mid-logarithmic bacteria. There is little doubt that ECg modifies the staphylococcal phenotype following interactions with the cell envelope. In common with cell wall- and CM-active antibiotics it invokes the cell wall stress stimulon, a set of genes up-regulated to preserve and repair a compromised cell wall or membrane. The relative affinity of galloyl catechins for lipid bilayers is dependent on their lipophilicity and they appear not to gain entry to the cytoplasm of bacteria to any great extent. ECg differs from EGCg only by the absence of a hydroxyl function at one of the meta positions on the B-ring, suggesting that reducing the degree of hydroxylation or the position of hydroxyl groups on the B-ring pharmacophore may increase bilayer affinity, with consequent increases in bioactivity. We therefore synthesized a number of unnatural ECg analogs differing in B-ring hydroxylation and in hydroxyl substitution of the fused A-C-ring moiety. In this study, we investigated the capacity of natural and ON1231320 synthetic galloyl catechins, as well as combinations of galloyl and non-galloyl catechins, to interact with artificial LPG:PG:CL membrane bilayers, alter the biophysical properties of the staphylococcal CM in situ and modulate gene expression in MRSA. The data has shed light on the potential for creating therapeutic catechin combinations for modulation of staphylococcal b-lactam resistance. However, exposure to ECg for this period of time enables the bacterial cell to substantially reconfigure the CM by increasing the proportion of branched chain fatty acids in the bilayer, leading to a fluid structure that compensates for the initial increased rigidity imposed by the rapid intercalation of the galloyl catechin into the membrane.Thus, at this time point, the transcriptomic response is unlikely to reflect the cellular response to the initial insult, an event that occurs immediately after exposure to the compound.