Cheah E, Carr P D, Suffolk P M, Vasudevan S G, Dixon N E, Ollis D L
Centre for Molecular Structure and Function, Research School of Chemistry, Australian National University, Canberra.
Structure. 1994 Oct 15;2(10):981-90. doi: 10.1016/s0969-2126(94)00100-6.
In Gram-negative proteobacteria, the nitrogen level in the cell is reflected by the uridylylation status of a key signal transducing protein, PII. PII modulates the activity of glutamine synthetase (GS) through its interaction with adenylyl transferase and it represses the expression of GS by acting in concert with nitrogen regulatory protein II.
The three-dimensional structure of the Escherichia coli PII trimer has been determined at 2.7 A resolution. PII shows a low level of structural similarity to a broad family of alpha/beta proteins and contains a double beta alpha beta motif. The PII trimer contains three beta-sheets, each of which is composed of strands from each of the three monomers. These are surrounded by six alpha-helices.
The structure of PII suggests potential regions of interaction with other proteins and serves as an initial step in understanding its signal transducing role in nitrogen regulation.
在革兰氏阴性变形杆菌中，细胞内的氮水平由关键信号转导蛋白PII的尿苷酰化状态反映。PII通过与腺苷酸转移酶相互作用来调节谷氨酰胺合成酶（GS）的活性，并且它与氮调节蛋白II协同作用来抑制GS的表达。
已确定大肠杆菌PII三聚体的三维结构，分辨率为2.7埃。PII与广泛的α/β蛋白家族显示出低水平的结构相似性，并包含一个双β-α-β基序。PII三聚体包含三个β-折叠，每个β-折叠由来自三个单体中的每一个的链组成。这些被六个α-螺旋包围。
PII的结构表明了与其他蛋白质相互作用的潜在区域，并作为理解其在氮调节中的信号转导作用的第一步。
