核糖核酸酶(RNase) 3、6和7，属于RNase A超家族，在感染时分泌，与细菌细胞壁的成分相互作用(Torrent M et al. 2010;普利多D等，2016a, b)。
核糖核酸酶A家族是脊椎动物特异性基因家族（咕SM＆卓小号2013）。序列同源性，独特的二硫键合三级结构，并能够水解聚合RNA（;罗森堡HF 2008 Beintema JJ＆Kleineidam RG 1998）的RNA酶A家族共享特定元素的成员。八名催化活性成员在人类中发现：RNase1（胰核糖核酸酶），RNASE2（嗜酸性粒细胞衍生神经毒素/ EDN），RNASE3（嗜酸性粒细胞阳离子蛋白/ ECP），RNase4，RNase5（血管生成素），RNASE6，RNase7（皮肤来源的RNaseA），和RNase8（RNase7的发散旁系同源）（索伦蒂诺S2010中）。人类基因组序列的分析道出了命名为RNA酶9-13五个额外的核糖核酸酶的存在，但他们似乎失去酶活性（Devor EJ等，2004;卡斯特拉S等2004;赵S等2005）。所有人类RNA酶A家族成员编码的14相对较小的多肽16kDa含有20的信号肽，以28个氨基酸的蛋白质的分泌。成熟的核糖核酸酶含有6〜8半胱氨酸残基是保持整体三级结构（索伦蒂诺S2010中）至关重要。除了核糖核酸酶活性的RNA酶A家族成员有牵连广泛的生物学作用，包括抗病原体和免疫调节活动（的哈德J＆施罗德JM 2002;鲁道夫B等2006;博伊克斯E等，2008;博伊克斯和诺盖，2007;斯潘塞JD等人2011; Becknell B等人，2015; Rosenberg的HF 2015）。抗菌性能的证据显示被归因于家庭宿主防御祖先角色远亲成员（皮佐E＆德阿莱西摹2007;罗森伯格HF等，2008）。
RNase3, RNase6和RNase7已被鉴定为最有效的人类抗菌核糖核酸酶，对革兰氏阳性和革兰氏阴性细菌具有广泛的抗菌作用(Pulido D等，2013,2016;张军等2003;Boix E et al. 2008;Torrent M et al. 2010)。突变分析显示，RNase7蛋白对P. aeruginosa、e.f aecium和e.c oli具有与野生型蛋白相似的抑菌活性，表明RNase7可以独立于其核糖核酸酶催化活性而杀灭细菌(Huang YC et al. 2007;Koten B et al. 2009)。关于核糖核酸酶非活性的RNase3和6蛋白对金黄色葡萄球菌的杀菌效果也有类似的报道(Rosenberg HF 1995;普利多D等，2016a)。RNase3、6和7是高pI的阳离子蛋白，可与生物膜的阴离子组分相互作用(Zhang J et . 2003;Boix E et al. 2008; Torrent M et al. 2010; Boix E et al. 2012; Pulido D et al. 2016a). RNase3, 6 and 7 present, respectively, a high number of either Arg, His or Lys surface-exposed residues that may contribute to their distinct bactericidal mechanisms of action (Torrent M et al. 2010; Prats-Ejarque G et al. 2016). RNase3 displays a membrane disruption capacity that is dependent on both surface exposed hydrophobic and cationic residues. RNase3 can bind and partially insert into the lipid bilayers, promoting its aggregation and final lysis, following a carpet-like mechanism. The RNase3 agglutination process precedes the bacterial death and lysis event. The antimicrobial properties of the RNase6 are comparable to its RNase3 homolog and correlate to the bacterial cell damage and agglutination activities (Pulido D et al. 2016a). In contrast, RNase7 has no significant membrane aggregation capacity (Torrent M et al. 2010). RNase7 binds and permeabilizes the bacterial membrane displaying a much higher leakage capacity compared to RNase3 (Torrent M et al. 2010; Huang YC et al. 2007). Membrane permeabilization by RNase7 required four clustered lysine residues but no catalytic residues (Huang YC et al. 2007). Binding to PGN and LPS has been reported for RNases 3 and 7 (Torrent M et al. 2010; Pulido D et al. 2016b). Studies using a battery of progressively truncated LPS-defective E. coli strains correlated the LPS interaction with the protein cell agglutination and bactericidal activities (Pulido D et al. 2012). Further work indicated that RNase3 and RNase 6 high cell agglutination activity towards Gram negative species is retained by their respective N-terminus peptides (Torrent M et al. 2012, 2013; Pulido D et al. 2016c). In particular, the RNase3 N-terminus encompasses a specific patch (Y33-R36) required for LPS binding and an hydrophobic aggregation prone region (A8-I16) that mediates the protein self amyloid- like aggregation and promotes the cell death.
