Guangdong Technology Research Center for Marine Algal Bioengineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, PR China.
Guangdong Technology Research Center for Marine Algal Bioengineering, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, PR China; Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, 518060, PR China.
Fish Shellfish Immunol. 2019 Nov;94:149-156. doi: 10.1016/j.fsi.2019.08.066. Epub 2019 Aug 26.
Anti-lipopolysaccharide factors (ALFs) are important host-defense molecules of crustaceans. They all contain a lipopolysaccharide-binding domain (LBD) and some ALFs exhibit strong antimicrobial activity. In this research, a Group G ALF from Penaeus monodon (ALFPm11) was studied. It is an anionic peptide specifically having a cationic and highly amphipathic LBD, with five positively charged residues separated by aromatic residues. It was abundantly expressed in the hepatopancreas of P. monodon normally but the expression level in other tissues was relatively low or undetectable. However, in the shrimps challenged by Vibrio, expression of ALFPm11 could be detected in all tissues. Chemically synthesized ALFPm11-LBD displayed high inhibitory activity (minimum inhibition concentration≤ 4 μM) against various bacteria, e.g. Exiguobacterium sp. L33, Bacillus sp. T2, and Acinetobacter sp. L32. It also displayed apparent activity in the agar well diffusion assay. Furthermore, it could efficiently induce agglutination of both Gram-positive and Gram-negative bacteria and cause significant membrane permeabilization of the bacteria. As a comparative study, ALFPm11-LBD showed a better or equal antimicrobial function to ALFPm3-LBD which was reported to possess strong antimicrobial activity against Gram-positive, Gram-negative bacteria and fungi. Thus, this research found a new effective ALF in P. monodon and demonstrated its antimicrobial mechanism, suggesting its potential applications in the future.
抗脂多糖因子（ALFs）是甲壳类动物重要的宿主防御分子。它们都含有一个脂多糖结合域（LBD），有些 ALFs 具有很强的抗菌活性。在这项研究中，研究了来自斑节对虾的 G 组 ALF（ALFPm11）。它是一种阴离子肽，具有阳离子和高度两亲性的 LBD，带有五个带正电荷的残基，由芳香族残基隔开。它在斑节对虾的肝胰腺中正常大量表达，但在其他组织中的表达水平相对较低或无法检测到。然而，在虾类受到弧菌挑战时，ALFPm11 在所有组织中都可以检测到表达。化学合成的 ALFPm11-LBD 对各种细菌表现出高抑制活性（最小抑制浓度≤4μM），例如极端芽孢杆菌 L33、芽孢杆菌 T2 和不动杆菌 L32。它在琼脂孔扩散测定中也表现出明显的活性。此外，它可以有效地聚集革兰氏阳性和革兰氏阴性细菌，并导致细菌的膜通透性显著增加。作为比较研究，ALFPm11-LBD 表现出比已经报道具有抗革兰氏阳性、革兰氏阴性细菌和真菌的强抗菌活性的 ALFPm3-LBD 更好或相等的抗菌功能。因此，本研究在斑节对虾中发现了一种新的有效 ALF，并阐明了其抗菌机制，表明其在未来具有潜在的应用价值。
