PinA inhibits ATP hydrolysis and energy-dependent protein degradation by Lon protease
PinA inhibits ATP hydrolysis and energy-dependent protein degradation by Lon protease
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DOI：
10.1074/jbc.273.1.524
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发表时间：
1998-01-02
影响因子：
4.8
通讯作者：
Maurizi, MR
中科院分区：
文献类型：
--
作者：
Hilliard, JJ;Simon, LD;Maurizi, MR
噬菌体T4 PinA蛋白抑制来自大肠杆菌的纯化的Lon蛋白酶对[H-3] α-甲基酪蛋白的降解，但抑制作用相对于酪蛋白是非竞争性的。PinA不抑制荧光肽N-戊二酰-丙氨酰丙氨酰苯丙氨酰-3-甲氧基萘酰胺的切割，而且，不阻断蛋白质底物如酪蛋白激活Lon对荧光肽的切割的能力，因此，PinA不阻断Lon上的蛋白水解活性位点或变构蛋白结合位点，对基础ATP酶活性的抑制是可变的（50-90%），而对蛋白激活的ATP酶活性的抑制通常为80- 95%，抑制对于ATP是非竞争性的，PinA不阻断ATP的不可水解类似物对肽切割的激活，这些数据表明PinA不结合在Lon的ATP酶活性位点，并且不干扰核苷酸与酶的结合，PinA抑制72个氨基酸的蛋白质CcdA的切割，CcdA的降解需要ATP水解，但是不抑制CcdA的羧基末端41个氨基酸片段的切割，其降解不需要ATP水解，因此PinA似乎在参与ATP水解和蛋白质水解之间偶联的新的调节或酶位点处相互作用，可能阻断Lon降解高分子量蛋白质底物所必需的蛋白质解折叠或重塑步骤。
The bacteriophage T4 PinA protein inhibited degradation of [H-3]alpha-methyl casein by purified Lon protease from Escherichia coli, but inhibition was noncompetitive with respect to casein, PinA did not inhibit cleavage of the fluorogenic peptide, N-glutaryl-alanylalanylphenylalanyl-3-methoxynaphthylamide and, moreover, did not block the ability of protein substrates, such as casein, to activate cleavage of fluorogenic peptides by Lon, Thus, PinA does not block the proteolytic active site or the allosteric protein-binding site on Lon, Inhibition of basal ATPase activity was variable (50-90%), whereas inhibition of protein-activated ATPase activity was usually 80-95%, Inhibition was noncompetitive with respect to ATP, PinA did not block activation of peptide cleavage by nonhydrolyzable analogs of ATP, These data suggest that PinA does not bind at the ATPase active site of Lon and does not interfere with nucleotide binding to the enzyme, PinA inhibited cleavage of the 72-amino acid protein, CcdA, degradation of which requires ATP hydrolysis, but did not inhibit cleavage of the carboxyl-terminal 41-amino acid fragment of CcdA, degradation of which does not require ATP hydrolysis, PinA thus appears to interact at a novel regulatory or enzymatic site involved in the coupling between ATP hydrolysis and proteolysis, possibly blocking the protein unfolding or remodeling step essential for degradation of high molecular weight protein substrates by Lon.