Cell-wall determinants of the bactericidal action of group IIA phospholipase A2 against Gram-positive bacteria

Abstract

). E. faecium strain 4 is highly susceptible to PLA 2 (LD 50 ∼50 ng/ml), whereas E. faecium strain 6 is less susceptible to PLA 2 (LD 50 ∼500 ng/ml).The S. aureus strains were grown overnight at 37°C, washed once, and then subcultured for either 2.5-3 h (mid-logarithmic phase) or ∼18 h (stationary phase) in fresh Trypticase Soy Broth (TSB; Difco Laboratories, Detroit, Michigan, USA) at a starting

Bactericidal Properties of Group IIA and Group V Phospholipases A2

“…The bactericidal effect of group IIA PLA 2 is highest against bacteria in the phase of logarithmic growth (15). This probably reflects the increased vulnerability of dividing bacteria and the ability of group IIA PLA 2 to reach the bacterial plasma membrane through the dividing cell wall.…”

Pseudomonas aeruginosa eradicates Staphylococcus aureus by manipulating the host immunity

“…Grampositive bacteria are much more sensitive to sPLA2-IIA than Gram-negative bacteria due to higher affinity of sPLA2-IIA to the cell walls of Gram-positive bacteria 14,17 . Selective hydrolysis of bacterial membrane phospholipids represents the critical step of bactericidal action of sPLA2-IIA 20 . This enzyme is the most potent bactericidal agent produced by mammals 17 and is, for example, the principal bactericidal molecule for SA in human tears 21 .…”

Role of Charge Properties of Bacterial Envelope in Bactericidal Action of Human Group IIA Phospholipase A2against Staphylococcus aureus

“…At least four steps are involved: binding of the enzyme to the bacterial cell surface, penetration of the enzyme through peptidoglycan layers, degradation of PL in the cell membrane, and activation of bacterial autolysins (11). The phospholipolytic activity of PLA 2 and, hence, ultimate bacterial killing requires calcium as a cofactor (8), but initial PLA 2 binding to the cell surface does not.…”

“…Briefly, bacteria were subcultured at 37°C to midlogarithmic phase in BM supplemented with 1 Ci/ml of [1][2][3][4][5][6][7][8][9][10][11][12][13][14] C]oleic acid and 0.01% BSA, washed, resuspended in half the volume of fresh BM medium without [1-14 C]oleic acid, and incubated for another 20 min at 37°C. BSA was then added to the medium to a final concentration of 0.5% (w/v), and bacteria were washed to remove remaining free oleic acid.…”

“…PL degradation products generated during PLA 2 treatment were quantitatively recovered in the extracellular medium as complexes with BSA (11). Therefore accumulation of radioactive material in extracellular supernatants after sedimentation (14,000 rpm for 4 min) of bacterial suspensions was used to routinely monitor PL degradation.…”