State Key Laboratory of Genetic Engineering, Fudan University, Shanghai 200433, China.
Mol Immunol. 2011 Jan;48(4):524-31. doi: 10.1016/j.molimm.2010.10.008. Epub 2010 Nov 18.
Lysozyme plays an important role in human innate immunity by causing bacterial cell lysis. We describe for the first time, the actual performance of human lysozyme g-like 2 (HLysG2), a mammalian g-type lysozyme. RT-PCR revealed that the HLysG2 gene was transcribed in eye and testis tissues. A spot was detected from human tears using 2D gel electrophoresis and was identified as HLysG2 using MALDI-TOF/TOF MS and a MASCOT search with a matching score of 140 and 27% sequence coverage of the whole amino acid sequence. To gain insight into the in vitro antimicrobial activities of HLysG2, the mature peptide-coding region was cloned into Pichia pastoris for heterogeneous expression. Recombinant HLysG2, had an optimal at pH 6.0 and 30 °C, reached the peak activity of 1.2 × 10(4)U/mg at the sodium ion concentration of 75 mM and showed a higher salt tolerance than human c-type lysozyme (HLysC). Recombinant HlysG2 inhibited Gram-positive bacterial growth and did not inhibit Gram-negative bacterial and Candida albicans growth. Results indicated that HLysG2 is a potent antibacterial protein that may play a role in the innate immunity of the human eye.
溶菌酶通过导致细菌细胞裂解在人类先天免疫中发挥重要作用。我们首次描述了哺乳动物 g 型溶菌酶人溶菌酶 g 样 2（HLysG2）的实际性能。RT-PCR 显示 HLysG2 基因在眼组织和睾丸组织中转录。使用二维凝胶电泳从人泪中检测到一个斑点，并使用 MALDI-TOF/TOF MS 和 MASCOT 搜索鉴定为 HLysG2，匹配得分为 140，整个氨基酸序列的序列覆盖率为 27%。为了深入了解 HLysG2 的体外抗菌活性，将成熟肽编码区克隆到毕赤酵母中进行异源表达。重组 HLysG2 的最佳 pH 值为 6.0，最佳温度为 30°C，在钠离子浓度为 75 mM 时达到 1.2×104U/mg 的峰值活性，并且比人 c 型溶菌酶（HLysC）具有更高的耐盐性。重组 HlysG2 抑制革兰氏阳性菌的生长，而不抑制革兰氏阴性菌和白色念珠菌的生长。结果表明，HLysG2 是一种有效的抗菌蛋白，可能在人眼的先天免疫中发挥作用。
