EXPORT AND SECRETION OF THE LIPOPROTEIN PULLULANASE BY KLEBSIELLA-PNEUMONIAE
EXPORT AND SECRETION OF THE LIPOPROTEIN PULLULANASE BY KLEBSIELLA-PNEUMONIAE
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DOI：
10.1111/j.1365-2958.1987.tb00534.x
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发表时间：
1987-07-01
影响因子：
3.6
通讯作者：
PUGSLEY, AP
中科院分区：
文献类型：
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作者：
DENFERT, C;CHAPON, C;PUGSLEY, AP
普鲁兰酶是肺炎克雷伯菌的一种分泌脂蛋白，通过蛋白酶和底物可及性以及免疫荧光试验显示，普鲁兰酶最初定位于外膜的外表面。冻融破坏这些细胞释放出与膜相关的和明显可溶形式的普鲁兰酶。膜相关普鲁兰酶与真正的外膜囊泡在异浓度蔗糖梯度离心下共分离，而准可溶性形式具有与内膜囊泡和细胞外普鲁兰酶聚集体相同的平衡密度。后者也含有外膜麦芽嘌呤，但在很大程度上缺乏其他膜成分，包括LPS和脂质。携带多拷贝普鲁兰酶结构基因（pulA）的肺炎克雷伯菌产生更多的细胞相关和分泌的普鲁兰酶，但大部分酶既不暴露在细胞表面也不释放到培养基中，即使在长时间孵育后也是如此。这表明普鲁兰酶分泌所需的因子被过量产生的普鲁兰酶饱和了。当pula在lacz启动子控制下表达时，产生的Pullulanase在任何时候都没有暴露在细胞表面，这表明Pullulanase分泌基因没有组成表达，并提出了它们与pum一样可能是麦芽糖调控的一部分的可能性。
Pullulanase, a secreted lipoprotein ofKlebsiella pneumoniae, is initially localized to the outer face of the outer membrane, as shown by protease and substrate accessibility and by immunofluorescence tests. Freeze‐thaw disruption of these cells released both membrane‐associated and apparently soluble forms of Pullulanase. Membrane‐associated Pullulanase co‐fractionated with authentic outer membrane vesicles upon isopycnic sucrose‐gradient centrifugation, whereas the quasi‐soluble form had the same equilibrium density as inner membrane vesicles and extracellular Pullulanase aggregates. The latter also contained outer membrane maltoporin, but were largely devoid of other membrane components including LPS and lipids. K. pneumoniae carrying multiple copies of the Pullulanase structural gene (pulA) produced increased amounts of cell‐associated and secreted Pullulanase, but a large proportion of the enzyme was neither exposed on the cell surface nor released into the medium, even after prolonged incubation. This suggests that factors necessary for Pullulanase secretion were saturated by the over‐produced Pullulanase. WhenpulAwas expressed underlacZpromoter control, the Pullulanase which was produced was not exposed on the cell surface at any time, suggesting that Pullulanase secretion genes are not expressed constitutively, and raising the possibility that they, likepuM, may be part of the maltose regulon.