RADIOLABELING OF PENICILLIN-BINDING PROTEINS (PBPS) IN INTACT PSEUDOMONAS-AERUGINOSA CELLS - CONSEQUENCES OF BETA-LACTAMASE ACTIVITY BY PBP-5
RADIOLABELING OF PENICILLIN-BINDING PROTEINS (PBPS) IN INTACT PSEUDOMONAS-AERUGINOSA CELLS - CONSEQUENCES OF BETA-LACTAMASE ACTIVITY BY PBP-5
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DOI：
10.1093/jac/19.6.733
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发表时间：
1987-06-01
影响因子：
5.2
通讯作者：
LIVERMORE, DM
中科院分区：
文献类型：
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作者：
LIVERMORE, DM
比较了9株青霉素结合蛋白(PBP)的完整细胞制剂和超声细胞制剂的标记时间过程，所有菌株的PBP图谱都相同。细胞内PBPs在35 mg/L 14[C]青霉素作用2分钟内全部饱和。PBP-5形成不稳定的青霉基络合物；其他PBPS形成高度稳定的络合物。在接触抗生素的2分钟内，完整细胞中的PBP-4出现饱和，这与该蛋白对青霉素的高亲和力有关。PBP1a、1b和3的标记是缓慢但渐进的，表明这些蛋白被细胞的通透性屏障(S)屏蔽。在35 mg/L 14[C]青霉素作用2~10min，完整细胞中PBP-5的标记达到10~20%饱和，但随后不再增加。这种行为可能表明在PBP-5-青霉素复合体的形成和破裂之间建立了一种稳定的状态，这表明PBP-5在通透性屏障的加强下，起着一种微弱的β-内酰胺酶的作用。这种活性可能会扭曲降低周质中青霉素浓度的其他多溴联苯的标记，从而使已被推荐作为细菌渗透性探针的多氯联苯的可及性实验无效。由于Noguchi等人，β-内酰胺酶的活性在耐药性中也可能是重要的。(Journal of抗生素，1980，33,1523-6)先前曾将铜绿假单胞菌中PBP-5-β-内酰胺酶活性的丧失与β-内酰胺类抗生素的过敏性联系在一起。
The time-course of labelling of penicillin-binding proteins (PBPs) was compared for intact and sonicated cell preparations of nine Pseudomonas aeruginosa strains, all of which gave identical PBP profiles. Saturation of all the PBPs in cell-sonicates occurred within 2 min of exposure to 35 mg/l 14[C] benzylpenicillin. PBP-5 formed an unstable penicilloyl-complex: the other PBPs formed highly stable complexes. Saturation of PBP-4 in intact cells occurred within 2 min of exposure to the antibiotic, correlating with the high affinity of this protein for penicillin. Labelling of PBPs 1a, 1b and 3 was slow but progressive, suggesting that these proteins were shielded by the permeability barrier(s) of the cell. Labelling of PBP-5 in intact cells achieved 10-20% saturation with 2-10 min of exposure to 35 mg/l 14[C] benzylpenicillin, but did not increase subsequently. This behaviour may indicate the establishment of a steady state between the formation and breakdown of the PBP-5-penicillin complex, suggesting that PBP-5, potentiated by the permeability barrier, functions as a feeble .beta.-lactamase. Such activity may distort the labelling of other PBPs reducing the concentration of penicillin in the periplasm, thus invalidating the PBP accessibility experiments that have been recommended as probes of bacterial permeability. The .beta.-lactamase activity also may be significant in resistance, since Noguchi et al. (Journal of Antibiotics, 1980, 33, 1523-6) have previously associated the loss of PBP-5-.beta.-lactamase activity with hypersusceptibility ot .beta.-lactams in P. aeruginosa.