Ancient conserved domains shared by animal soluble guanylyl cyclases and bacterial signaling proteins.
Ancient conserved domains shared by animal soluble guanylyl cyclases and bacterial signaling proteins.
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DOI：
10.1186/1471-2164-4-5
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发表时间：
2003-02-03
期刊：
影响因子：
4.4
通讯作者：
Aravind L
中科院分区：
文献类型：
--
作者：
Iyer LM;Anantharaman V;Aravind L
可溶性胍基环化酶（SGCs）是动物一氧化氮（NO）下游转导信号的二聚体酶。它们通过与它们的n端延伸结合的血红素片段来感知NO。通过序列特征搜索，我们发现sgc的n端扩展包含两个球状结构域。其中第一个，HNOB（血红素NO结合）结构域，主要是α-螺旋结构域，通过共价键与组氨酸结合血红素。缺乏这种保守组氨酸的版本可能与血红素非共价相互作用。我们在几个细菌谱系中检测到HNOB结构域，在那里它们与趋化受体的甲基接受结构域融合或作为独立的蛋白质。独立形式由预测的操纵子编码，该操纵子还包含双组分信号系统和ggdef型核苷酸环化酶的基因。第二个结构域，HNOB相关结构域（HNOBA）发生在动物SGCs中的HNOB和环化酶结构域之间。细菌中也检测到HNOBA结构域，并且总是由一个基因编码，该基因发生在HNOB结构域的基因附近。在细菌和动物中，HNOB结构域被预测为气体配体的血红素依赖传感器，并转导多种下游信号。HNOBA结构域在功能上与HNOB结构域相互作用，并可能与配体结合，要么合作，要么独立于后者。系统发育分析表明，HNOB和HNOBA结构域是通过细菌源的横向转移获得的。
Soluble guanylyl cyclases (SGCs) are dimeric enzymes that transduce signals downstream of nitric oxide (NO) in animals. They sense NO by means of a heme moiety that is bound to their N-terminal extensions. Using sequence profile searches we show that the N-terminal extensions of the SGCs contain two globular domains. The first of these, the HNOB (Heme NO Binding) domain, is a predominantly α-helical domain and binds heme via a covalent linkage to histidine. Versions lacking this conserved histidine and are likely to interact with heme non-covalently. We detected HNOB domains in several bacterial lineages, where they occur fused to methyl accepting domains of chemotaxis receptors or as standalone proteins. The standalone forms are encoded by predicted operons that also contain genes for two component signaling systems and GGDEF-type nucleotide cyclases. The second domain, the HNOB associated (HNOBA) domain occurs between the HNOB and the cyclase domains in the animal SGCs. The HNOBA domain is also detected in bacteria and is always encoded by a gene, which occurs in the neighborhood of a gene for a HNOB domain. The HNOB domain is predicted to function as a heme-dependent sensor for gaseous ligands, and transduce diverse downstream signals, in both bacteria and animals. The HNOBA domain functionally interacts with the HNOB domain, and possibly binds a ligand, either in cooperation, or independently of the latter domain. Phyletic profiles and phylogenetic analysis suggest that the HNOB and HNOBA domains were acquired by the animal lineage via lateral transfer from a bacterial source.
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