Abstract

The iron-containing protein neuroglobin (Ngb) involved in the transport of oxygen is generally considered the precursor of all animal globins. In this report, we studied the structure of Ngb of the cold-water sponge Halisarca dujardinii. In sponges, the oldest multicellular organisms, the Ngb gene contains three introns. In contrast to human Ngb, its promoter contains a TATA-box, rather than CG-rich motifs. In sponges, Ngb consists of 169 amino acids showing rather low similarity with its mammalian orthologues. It lacks Glu and Arg residues in positions required for prevention of hypoxia-related apoptosis. Nevertheless, Ngb contains both proximal and distal conserved heme-biding histidines. The primary structure of H. dujardinii neuroglobin predicted by sequencing was confirmed by mass-spectrometry analysis of recombinant Ngb expressed in E. coli. The high level of Ngb expression in sponge tissues suggests its possible involvement in the gas metabolism and presumably in other key metabolic processes in H. dujardinii.

中文翻译：

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冷水海绵哈利萨杜氏菌中神经球蛋白的结构

摘要

通常认为，参与氧气运输的含铁蛋白质神经球蛋白（Ngb）是所有动物球蛋白的前体。在本报告中，我们研究了冷水海绵Halisarca dujardinii的Ngb的结构。在海绵（最古老的多细胞生物）中，Ngb基因包含三个内含子。与人Ngb相反，其启动子包含TATA框，而不是富含CG的基序。在海绵中，Ngb由169个氨基酸组成，与哺乳动物的直向同源物显示出相当低的相似性。它在防止缺氧相关的细胞凋亡所需的位置缺少Glu和Arg残基。尽管如此，Ngb包含近端和远端保守的血红素组氨酸。的主要结构通过质谱分析在大肠杆菌中表达的重组Ngb确认了测序预测的杜氏嗜血杆菌神经球蛋白。Ngb在海绵组织中的高水平表达表明其可能参与了气体代谢，并可能参与了杜氏烟草的其他关键代谢过程。