Sára M, Kuen B, Mayer H F, Mandl F, Schuster K C, Sleytr U B
Zentrum für Ultrastrukturforschung, Universität für Bodenkultur, Vienna, Austria.
J Bacteriol. 1996 Apr;178(7):2108-17. doi: 10.1128/jb.178.7.2108-2117.1996.
Stable synthesis of the hexagonally ordered (p6) S-layer protein from the wild-type strain of Bacillus stearothermophilus PV72 could be achieved in continuous culture on complex medium only under oxygen-limited conditions when glucose was used as the sole carbon source. Depending on the adaptation of the wild-type strain to low oxygen supply, the dynamics in oxygen-induced changes in S-layer protein synthesis was different when the rate of aeration was increased to a level that allowed dissimilation of amino acids. If oxygen supply was increased at the beginning of continuous culture, synthesis of the p6 S-layer protein from the wild-type strain (encoded by the sbsA gene) was immediately stopped and replaced by that of a new type of S-layer protein (encoded by the sbsB gene) which assembled into an oblique (p2) lattice. In cells adapted to a prolonged low oxygen supply, first, low-level p2 S-layer protein synthesis and second, synchronous synthesis of comparable amounts of both types of S-layer proteins could be induced by stepwise increasing the rate of aeration. The time course of changes in S-layer protein synthesis was followed up by immunogold labelling of whole cells. Synthesis of the p2 S-layer protein could also be induced in the p6-deficient variant T5. Hybridization data obtained by applying the radiolabelled N-terminal and C-terminal sbsA fragments and the N-terminal sbsB fragment to the genomic DNA of all the three organisms indicated that changes in S-layer protein synthesis were accompanied by chromosomal rearrangement. Chemical analysis of peptidoglycan-containing sacculi and extraction and recrystallization experiments revealed that at least for the wild-type strain, a cell wall polymer consisting of N-acetylglucosamine and glucose is responsible for binding of the p6 S-layer protein to the rigid cell wall layer.
只有在以葡萄糖作为唯一碳源的复合培养基上进行连续培养且处于限氧条件下时，嗜热脂肪芽孢杆菌PV72野生型菌株才能稳定合成六方有序（p6）S层蛋白。根据野生型菌株对低氧供应的适应性，当通气速率提高到允许氨基酸异化的水平时，氧气诱导的S层蛋白合成变化动态有所不同。如果在连续培养开始时增加氧气供应，野生型菌株（由sbsA基因编码）的p6 S层蛋白合成会立即停止，并被一种新型S层蛋白（由sbsB基因编码）的合成所取代，这种新型S层蛋白组装成斜交（p2）晶格。在适应长时间低氧供应的细胞中，首先，通过逐步提高通气速率可诱导低水平的p2 S层蛋白合成，其次，可诱导两种类型的S层蛋白同步合成相当数量。通过对全细胞进行免疫金标记来跟踪S层蛋白合成变化的时间进程。在p6缺陷变体T5中也可诱导p2 S层蛋白的合成。通过将放射性标记的sbsA基因N端和C端片段以及sbsB基因N端片段应用于所有三种生物体的基因组DNA获得的杂交数据表明，S层蛋白合成的变化伴随着染色体重排。对含肽聚糖的细胞壁囊泡进行化学分析以及提取和重结晶实验表明，至少对于野生型菌株而言，一种由N-乙酰葡糖胺和葡萄糖组成的细胞壁聚合物负责将p6 S层蛋白结合到刚性细胞壁层上。
