CF45-1, a secreted protein which participates in Dictyostelium group size regulation
CF45-1, a secreted protein which participates in Dictyostelium group size regulation
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DOI：
10.1128/ec.2.4.788-797.2003
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发表时间：
2003-08-01
期刊：
影响因子：
--
通讯作者：
Gomer, RH
中科院分区：
文献类型：
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作者：
Brock, DA;Hatton, RD;Gomer, RH
发育中的网柄菌细胞聚集形成子实体，通常含有2×104个细胞。为了防止形成过大的子实体，如果细胞太多，聚集的细胞流就会分裂成组。这种分解是由一种名为计数因子(CF)的多肽分泌复合体调节的。Countin和CF50是CF的两个组成部分。干扰这两种蛋白质的表达会导致细胞分泌非常少的可检测到的CF活性，结果是聚集流保持完好并形成大的子实体，子实体总是崩溃。我们发现，破坏编码粗纤维中存在的第三种蛋白质CF45-1的基因，也会导致细胞在琼脂平板上与细菌一起生长并饥饿时形成大群。然而，与Countin(-)和cf50(-)细胞不同，当细胞在滤片上饥饿时，cf45-1(-)细胞有时形成比野生型细胞更小的群体。预测的CF45-1氨基酸序列与溶菌酶有一定的相似性，但重组CF45-1没有检测到溶菌酶活性。在饥饿细胞的渗出物中，CF45-1存在于一个类似于450 kDa的组分中，其中也包含Countin和CF50，这表明它是复合体的一部分。重组CF45-1减少了cf45-1(-)细胞集落和野生型和cf50(-)细胞集落的大小，其中cf45-1(-)细胞的半数有效浓度(EC50)接近8 ng/ml，野生型和cf50(-)细胞的EC50接近40 ng/ml。与Countin-和CF50(-)细胞一样，CF45-1(-)细胞具有高水平的胞浆葡萄糖，高细胞粘附力和低细胞活力。综上所述，这些数据表明CF45-1(-)参与了Diciyostelius中群体大小的调节。
Developing Dictyostelium cells aggregate to form fruiting bodies containing typically 2 X 104 cells. To prevent the formation of an excessively large fruiting body, streams of aggregating cells break up into groups if there are too many cells. The breakup is regulated by a secreted complex of polypeptides called counting factor (CF). Countin and CF50 are two of the components of CF. Disrupting the expression of either of these proteins results in cells secreting very little detectable CF activity, and as a result, aggregation streams remain intact and form large fruiting bodies, which invariably collapse. We find that disrupting the gene encoding a third protein present in crude CF, CF45-1, also results in the formation of large groups when cells are grown with bacteria on agar plates and then starve. However, unlike countin(-) and cf50(-) cells, cf45-1(-) cells sometimes form smaller groups than wild-type cells when the cells are starved on filter pads. The predicted amino acid sequence of CF45-1 has some similarity to that of lysozyme, but recombinant CF45-1 has no detectable lysozyme activity. In the exudates from starved cells, CF45-1 is present in a similar to450-kDa fraction that also contains countin and CF50, suggesting that it is part of a complex. Recombinant CF45-1 decreases group size in colonies of cf45-1(-) cells with a 50% effective concentration (EC50) of similar to8 ng/ml and in colonies of wild-type and cf50(-) cells with an EC50 of similar to40 ng/ml. Like countin- and cf50(-) cells, cf45-1(-) cells have high levels of cytosolic glucose, high cell-cell adhesion, and low cell motility. Together, the data suggest that CF45-1(-) participates in group size regulation in Diciyostelium.