SpALF4: A newly identified anti-lipopolysaccharide factor from the mud crab Scylla paramamosain with broad spectrum antimicrobial activity |
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| Institution: | 1. East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai 200090, China;2. Key Laboratory of East China Sea and Oceanic Fishery Resources Exploitation, Ministry of Agriculture, Shanghai 200090, China;3. School of Life Sciences, Shandong University, Jinan, Shandong 250100, China;4. College of Fisheries, Henan Normal University, Xinxiang, Henan 453007, China;1. Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China;2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China;3. National & Local Joint Engineering Laboratory of Ecological Mariculture, 7 Nanhai Road, Qingdao 266071, China;1. Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, China;4. National & Local Joint Engineering Laboratory of Ecological Mariculture, 7 Nanhai Road, Qingdao 266071, China;1. Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;3. National & Local Joint Engineering Laboratory of Ecological Mariculture, Qingdao 266071, China;1. State Key Laboratory of Marine Environmental Science, College of Ocean & Earth Science, Xiamen University, Xiamen, Fujian, PR China;2. Fujian Collaborative Innovation Center for Exploitation and Utilization of Marine Biological Resources, Xiamen, Fujian, PR China;3. Fujian Engineering Laboratory of Marine Bioproducts and Technology, Xiamen University, Xiamen, Fujian, PR China;1. Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, China;2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China;1. Strong Biotech Corporation, Taipei 115, Taiwan, ROC;2. Department of Microbiology, Soochow University, Taipei 111, Taiwan, ROC |
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| Abstract: | Anti-lipopolysaccharide factors (ALFs) are antimicrobial peptides with binding and neutralizing activities to lipopolysaccharide (LPS) in crustaceans. This study identified and characterized a novel ALF homolog (SpALF4) from the mud crab Scylla paramamosain. The complete cDNA of SpALF4 had 756 bp with a 381 bp open reading frame encoding a protein with 126 aa. The deduced protein contained a signal peptide and a LPS-binding domain. SpALF4 shared the highest identity with PtALF5 at amino acid level but exhibited low similarity with most of other crustacean ALFs. Furthermore, different from the previously identified three SpALF homologs and most of other ALFs, SpALF4 had a low isoelectric point (pI) for the mature peptide and the LPS-binding domain with the values of 6.93 and 6.74, respectively. These results indicate that SpALF4 may be a unique ALF homolog with special biological function in the mud crab. Similar to the spatial structure of ALFPm3, SpALF4 contains three α-helices packed against a four-strand β-sheet, and an amphipathic loop formed by a disulphide bond between two conserved cysteine residues in LPS-binding domain. SpALF4, mainly distributed in hemocytes, could be upregulated by Vibrio harveyi, Staphylococcus aureus, or white spot syndrome virus. Recombinant SpALF4 could inhibit the growth of Gram-negative bacteria (V. harveyi, Vibrio anguillarum, Vibrio alginolyticus, Aeromonas hydrophila, Pseudomonas putida), Gram-positive bacteria (S. aureus and Bacillus megaterium), and a fungus Candida albicans to varying degrees. Further study showed that it could also bind to all the aforementioned microorganisms except S. aureus. These results demonstrate that SpALF4 is a unique ALF homolog with potent antimicrobial activity against bacteria and fungi. This characteristic suggests SpALF4 plays an essential function in immune defense against pathogen invasion in mud crab. |
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| Keywords: | Expression pattern Binding activity Antimicrobial activity |
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