Control of phycobiliprotein proteolysis and heterocyst differentiation in Anabaena
Control of phycobiliprotein proteolysis and heterocyst differentiation in Anabaena
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鱼腥藻藻胆蛋白水解和异形细胞分化的控制
DOI：
10.1128/jb.141.3.1375-1385.1980
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发表时间：
1980
影响因子：
3.2
通讯作者：
R. Haselkorn
中科院分区：
文献类型：
--
作者：
N. Wood;R. Haselkorn
藻胆蛋白的降解可以在蓝藻培养中通过去除培养基中的组合氮来启动。在这种条件下，某些水藻菌株分化出专门用于有氧固氮的细胞（异囊）。我们在这里描述了一种从异囊或营养细胞中提取提取物的制备过程，该提取物含有一种在体外只能降解可溶性水藻蛋白混合物中的藻胆蛋白的活性。在氮饥饿条件下或用谷氨酰胺合成酶抑制剂甲硫氨酸亚砜处理的充满氨培养物中，这种活性增加。氯霉素和碳饥饿均能抑制氮饥饿诱导的活性增加。在所有这些条件下，体外测定的藻胆蛋白降解活性与体内藻胆蛋白吸收损失相关。最后，在氨存在的情况下，为获取蛋氨酸而饥饿的水藻营养不良体不会导致体内藻胆蛋白的降解或蛋白酶活性的增加。结合ppGpp的直接测量，这些结果表明，在水藻中的蛋白质水解不受与大肠杆菌严格反应相关的化合物的控制。由于蛋白酶活性的增加似乎受到控制异囊分化的相同变量的调节，因此该活性应该为分化的早期事件提供有用的生化标记。
Phycobiliprotein degradation can be initiated in cultures of the cyanobacterium Anabaena by removal of combined nitrogen from the medium. Certain strains of Anabaena differentiate cells specialized for aerobic nitrogen fixation (heterocysts) under such conditions. We describe here a procedure for the preparation of extracts from heterocysts or vegetative cells that contain an activity capable of degrading only the phycobiliproteins in a mixture of soluble Anabaena proteins in vitro. This activity increased under nitrogen starvation conditions or in ammonia-replete cultures treated with the glutamine synthetase inhibitor methionine sulfoximine. The increase in activity induced by nitrogen starvation was prevented by chloramphenicol or by carbon starvation. Under all these conditions, phycobiliprotein degradative activity assayed in vitro was correlated with the loss of phycobiliprotein absorbance in vivo. Finally, starvation of a met auxotroph of Anabaena for methionine (in the presence of ammonia) did not induce phycobiliprotein degradation in vivo or the increase in proteinase activity. Together with direct measurements of ppGpp, these results indicate that proteolysis in Anabaena is not controlled by compounds associated with the stringent response in Escherichia coli. Since the increase in proteinase activity appears to be regulated by the same variables that control heterocyst differentiation, the activity should provide a useful biochemical marker for the early events of differentiation.