Globin-coupled sensors: A class of heme-containing sensors in Archaea and Bacteria
Globin-coupled sensors: A class of heme-containing sensors in Archaea and Bacteria
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DOI：
10.1073/pnas.161185598
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发表时间：
2001-07-31
影响因子：
11.1
通讯作者：
Alam, M
中科院分区：
文献类型：
--
作者：
Hou, SB;Freitas, T;Alam, M
最近发现的原核生物信号转导子HemAT介导了趋氧性反应，已在细菌和细菌中进行了描述。来自古菌盐生盐杆菌（Halobacterium salinarum，HemAT-Hs）和来自革兰氏阳性细菌枯草芽孢杆菌（Bacillus subtilis，HemAT-Bs）的HemAT的N-末端区域含有肌红蛋白样基序，显示特征性血红素蛋白吸收光谱，并且可逆地结合氧。分别短于195和176个残基的重组HemAT-Hs和HemAT-Bs不能有效地结合血红素。序列同源性比较和三维建模预测His-123是来自两个物种的HemAT中的近端血红素结合残基。这里描述的工作使用位点特异性诱变和光谱学来证实这一预测，从而为原核生物信号转导子的功能域提供直接证据，该功能域在珠蛋白折叠中结合血红素。我们假设，这个域是一个球蛋白偶联传感器（GCS）基序的一部分，存在作为一个两个域的换能器没有相似性的PER-ARNT-SIM（PAS）域超家族换能器。使用GCS基序，我们已经确定了几个双域传感器在各种原核生物。我们克隆、表达和纯化了两个潜在的球蛋白偶联传感器，并对它们进行了光谱分析。两者都结合血红素，并显示肌红蛋白样光谱。这一观察结果表明，GCS型换能器的一般功能是结合双原子氧和其他气态配体，并通过连接的信号传导结构域传递构象信号。
The recently discovered prokaryotic signal transducer HemAT, which has been described in both Archaea and Bacteria, mediates aerotactic responses. The N-terminal regions of HemAT from the archaeon Halobacterium salinarum (HemAT-Hs) and from the Gram-positive bacterium Bacillus subtilis (HemAT-Bs) contain a myoglobin-like motif, display characteristic heme-protein absorption spectra, and bind oxygen reversibly. Recombinant HemAT-Hs and HemAT-Bs shorter than 195 and 176 residues, respectively, do not bind heme effectively. Sequence homology comparisons and three-dimensional modeling predict that His-123 is the proximal heme-binding residue in HemAT from both species. The work described here used site-specific mutagenesis and spectroscopy to confirm this prediction, thereby providing direct evidence for a functional domain of prokaryotic signal transducers that bind heme in a globin fold. We postulate that this domain is part of a globin-coupled sensor (GCS) motif that exists as a two-domain transducer having no similarity to the PER-ARNT-SIM (PAS)-domain superfamily transducers. Using the GCS motif, we have identified several two-domain sensors in a variety of prokaryotes. We have cloned, expressed, and purified two potential globin-coupled sensors and performed spectral analysis on them. Both bind heme and show myoglobin-like spectra. This observation suggests that the general function of GCS-type transducers is to bind diatomic oxygen and perhaps other gaseous ligands, and to transmit a conformational signal through a linked signaling domain.