Gromova Tania Yu, Demidyuk Ilya V, Kozlovskiy Viacheslav I, Kuranova Inna P, Kostrov Sergey V
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia.
Biochimie. 2009 May;91(5):639-45. doi: 10.1016/j.biochi.2009.03.008. Epub 2009 Mar 25.
Protealysin, a protease previously described by us in Serratia proteamaculans, belongs to the group of thermolysin-like proteases (TLPs) that differ from classical TLPs by the precursor structural organization. The propeptide of protealysin precursor has no significant structural similarity to the propeptides of most TLPs. The functions of protealysin-like precursors and mechanisms of their action remain unclear. We studied the pathway of protealysin precursor processing in vitro using standard approaches: modification of the catalytic site and monitoring immobilized precursor maturation. The Glu(113) --> Ala substitution inhibited the precursor maturation, which pointed to the autocatalytic processing. The mutant precursor exposure to active protealysin converted it to the mature enzyme, thus, indicating the intermolecular processing. Intermolecular processing of the mutant protein by other proteases such as thermolysin or subtilisin is also possible. The intact protealysin precursor was efficiently autoprocessed in solution but not after immobilization. These data indicate that the processing of protealysin precursor differs from that of classical TLPs. The protealysin propeptide is cleaved by an autocatalytic or heterocatalytic intermolecular mechanism and is most likely not removed intramolecularly.
蛋白酶解素是我们之前在粘质沙雷氏菌中描述过的一种蛋白酶，属于嗜热菌蛋白酶样蛋白酶（TLP）家族，其前体结构组织与经典TLP不同。蛋白酶解素前体的前肽与大多数TLP的前肽没有显著的结构相似性。蛋白酶解素样前体的功能及其作用机制仍不清楚。我们使用标准方法在体外研究了蛋白酶解素前体的加工途径：催化位点的修饰和固定化前体成熟的监测。Glu(113)→Ala取代抑制了前体的成熟，这表明存在自催化加工。将突变前体暴露于活性蛋白酶解素可将其转化为成熟酶，因此表明存在分子间加工。突变蛋白也可能被其他蛋白酶如嗜热菌蛋白酶或枯草杆菌蛋白酶进行分子间加工。完整的蛋白酶解素前体在溶液中能有效进行自我加工，但固定化后则不能。这些数据表明，蛋白酶解素前体的加工与经典TLP不同。蛋白酶解素前肽通过自催化或异催化分子间机制被切割，很可能不是通过分子内方式去除的。
