Interaction between the individual isoenzymes of pyruvate dehydrogenase kinase and the inner lipoyl-bearing domain of transacetylase component of pyruvate dehydrogenase complex.
Interaction between the individual isoenzymes of pyruvate dehydrogenase kinase and the inner lipoyl-bearing domain of transacetylase component of pyruvate dehydrogenase complex.
复制标题
丙酮酸脱氢酶激酶的各个同工酶与丙酮酸脱氢酶复合物的转乙酰酶组分的内部硫酰基承载结构域之间的相互作用。
DOI：
10.1042/bj20020301
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Popov,KirillM
中科院分区：
文献类型：
--
作者：
Tuganova,Alina;Boulatnikov,Igor;Popov,KirillM
蛋白质间相互作用在丙酮酸脱氢酶激酶（PDK）的活性调节中起着重要作用。通常认为，PDK与丙酮酸脱氢酶复合物的转乙酰酶组分E2的内部硫辛酰基承载结构域L2的结合在很大程度上决定了激酶活性的水平。在本研究中，我们的特点之间的相互作用的个别同工酶的PDK（PDK 1-PDK 4）和单体L2域的人E2，以及这种相互作用对激酶活性的影响。结果发现，PDK同工酶是显着不同的，就其亲和力为L2。PDK 3表现出非常紧密的结合，其在使用尺寸排阻色谱分离PDK 3-L2复合物期间持续存在。PDK 1和PDK 2的结合是容易可逆的，表观解离常数约为100。两种同工酶均为10μM。PDK 4与L2结合的能力大大降低（相对顺序为PDK 3> PDK 1 = PDK 2> PDK 4）。单独的单体L2结构域对PDK 1或PDK 2的活性几乎没有影响。相比之下，L2导致PDK 3活性增加3倍，并且大约增加10%。PDK 4活性增加37%。这些结果强烈表明，PDK和L2结构域的各个同工酶之间的相互作用是同工酶特异性的，并且可能是决定特定同工酶对丙酮酸脱氢酶复合物的激酶活性水平的主要因素之一。
Protein—protein interactions play an important role in the regulation of enzymic activity of pyruvate dehydrogenase kinase (PDK). It is generally believed that the binding of PDK to the inner lipoyl-bearing domain L2 of the transacetylase component E2 of pyruvate dehydrogenase complex largely determines the level of kinase activity. In the present study, we characterized the interaction between the individual isoenzymes of PDK (PDK1—PDK4) and monomeric L2 domain of human E2, as well as the effect of this interaction on kinase activity. It was found that PDK isoenzymes are markedly different with respect to their affinities for L2. PDK3 demonstrated a very tight binding, which persisted during isolation of PDK3—L2 complexes using size-exclusion chromatography. Binding of PDK1 and PDK2 was readily reversible with the apparent dissociation constant of approx. 10μM for both isoenzymes. PDK4 had a greatly reduced capacity for L2 binding (relative order PDK3>PDK1 = PDK2>PDK4). Monomeric L2 domain alone had very little effect on the activities of either PDK1 or PDK2. In contrast, L2 caused a 3-fold increase in PDK3 activity and approx. 37% increase in PDK4 activity. These results strongly suggest that the interactions between the individual isoenzymes of PDK and L2 domain are isoenzyme-specific and might be among the major factors that determine the level of kinase activity of particular isoenzyme towards the pyruvate dehydrogenase complex.