Comparative sequence analysis of myosin heavy chain proteins from congeneric shallow- and deep-living rattail fish (genus Coryphaenoides)
Comparative sequence analysis of myosin heavy chain proteins from congeneric shallow- and deep-living rattail fish (genus Coryphaenoides)
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DOI：
10.1242/jeb.017137
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发表时间：
2008-05-01
影响因子：
2.8
通讯作者：
Morita, Takami
中科院分区：
文献类型：
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作者：
Morita, Takami
功能基因对高压生活的进化适应性还没有得到很好的理解。为了阐明蛋白质对高压的适应机制，我们从两种深海鱼类Coryphaenoides yaquinae和Coryphaenoides yaquinae的骨骼肌中克隆了肌球蛋白重链（MyHC）cDNA。armatus和两种非深海鱼类C. acrolepis和C.灰色的与非深海鱼类相比，深海鱼类的MyHCs在loop-1和loop-2两个环区具有独特的结构。深海鱼类的loop-1区域具有Pro残基，loop-2区域是肌动蛋白结合位点，比非深海鱼类的相同区域短。loop-1区域中的氨基酸取代预计主要涉及ATP酶活性，而loop-2区域中的缺失影响MyHC与肌动蛋白丝在高压下的结合。此外，深海鱼类的MyHC在杆状区域的卷曲螺旋结构中的核心位置具有偏向性的氨基酸替换。这些氨基酸取代可能会减少卷曲螺旋结构中的空腔，从而使结构更紧凑，不受高压的影响。总之，这些结果表明，氨基酸取代可以适应性地改变蛋白质的压力敏感性，即使它们不直接影响核心结构。
The evolutionary adaptations of functional genes to life at high pressure are not well understood. To elucidate the mechanisms of protein adaptation to high pressure, we cloned the myosin heavy chain (MyHC) cDNA from skeletal muscle of two deep-sea fishes, Coryphaenoides yaquinae and C. armatus, and two non-deep-sea fishes, C. acrolepis and C. cinereus. The MyHCs of deep-sea fishes have a unique structure in two loop regions, loop-1 and loop-2, in comparison with those of non-deep-sea fishes. The loop-1 region of deep-sea fishes has a Pro residue and the loop-2 region, which is an actin-binding site, is shorter than the same region in non-deep-sea fishes. The amino acid substitution in the loop-1 region is expected to be mainly involved in ATPase activity, whereas the deletion in the loop-2 region affects the association of MyHC with actin filaments at high pressure. In addition, the MyHC of deep-sea fishes has biased amino acid substitutions at core positions in the coiled-coil structure of the rod region. These amino acid substitutions are likely to decrease the cavities in the coiled-coil structure and consequently make the structure more compact and unaffected by high pressure. Together, these results indicate that amino acid substitutions can adaptively alter the pressure sensitivity of a protein even if they do not directly influence core structure.