Liu Mei, Zhang Shicui, Liu Zhenhui, Li Hongyan, Xu Anlong
Department of Marine Biology, Ocean University of China, Qingdao, 266003, P.R. China.
Gene. 2006 Feb 15;367:110-7. doi: 10.1016/j.gene.2005.09.017. Epub 2005 Dec 15.
The study on lysozymes remains open in amphioxus, a cephalochordate. Here we show the existence of c-type lysozyme gene (AmphiLysC) in amphioxus, first such data in the basal chordates including urochordate and cephalochordate. This is in contrast to the absence of c-type lysozyme genes in urochordate. It is found that there exist two copies of c-type lysozyme genes in amphioxus genome, and their gene organization is similar to vertebrate c-type lysozyme genes with respect to the number and the size of both exons and introns. AmphiLysC possesses main features characteristic of the digestive c-type lysozyme such as lower number of basic amino acids (low pI values) and pH-optimum in acidic range. Moreover, AmphiLysC is predominantly expressed in the gut. These indicate that AmphiLysC is possibly a digestive c-type enzyme. However, the ubiquitous expression of AmphiLysC in non-digestive tissues such as ovaries, testes, notochord, gill and muscle suggests that it may also play a non-digestive role like antibacterial activity. It is highly likely that AmphiLysC is an enzyme with a combined function of digestion and bacteriolysis.
文昌鱼（一种头索动物）中溶菌酶的研究仍未明确。在此我们展示了文昌鱼中c型溶菌酶基因（AmphiLysC）的存在，这是包括尾索动物和头索动物在内的基础脊索动物中的首个此类数据。这与尾索动物中不存在c型溶菌酶基因形成对比。研究发现文昌鱼基因组中存在两个c型溶菌酶基因拷贝，并且它们的基因结构在内外显子的数量和大小方面与脊椎动物的c型溶菌酶基因相似。AmphiLysC具有消化性c型溶菌酶的主要特征，例如碱性氨基酸数量较少（低pI值）以及在酸性范围内的最适pH值。此外，AmphiLysC主要在肠道中表达。这些表明AmphiLysC可能是一种消化性c型酶。然而，AmphiLysC在卵巢、睾丸、脊索、鳃和肌肉等非消化组织中的广泛表达表明它可能也发挥非消化性作用，如抗菌活性。很有可能AmphiLysC是一种具有消化和溶菌双重功能的酶。
