Purification and Molecular Identification of an Antifungal Peptide from the Hemolymph of Musca domestica （housefly）

Antibacterial and antifungal peptides found in houseflies （Musca domestica） in large number are indispensable components of its immune defense mechanism. In this study the anterior tip of the larvae of housefly was cut off with a pair of fine scissors and hemolymph was collected and exuded in an ice-cold test tube. From the hemolymph an antifungal substance was isolated by solid-phase extraction combined with reverse phase-high performance liquid chromotography （RP-HPLC） and named as Musca domestica antifungal peptide-1 （MAF-1）. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis （SDS-PAGE） showed its molecular weight was 17 kDa. UV absorption spectra revealed that this antifungal substance possessed the characteristics of protein peptides. Analysis by fingerprint-identification and tandem mass spectrometry suggested MAF-I was an unknown protein. Edman degradation identified the sequence of 30 amino acids of its N-terminal which matched no peptide in the MASCOT search database, indicating MAF-1 was a novel insect antifungal peptide. Mass spectrometry showed the precise molecular weight of MAF-1 was 17203.384 Da. Its isoelectric point was acidic.

Analysis of the effects of antifungal peptide P-1 from Bacillus pumilus HN-10 on energy metabolism of Trichothecium roseum

This study investigated the antifungal activity and possible mode of action of Bacillus pumilus HN-10 antifungal peptide P-1 against Trichothecium roseum.The results showed that the antifungal peptide P-1 at a concentration of 1.0μg mL^(-1)had strong antifungal activity against T.roseum.P-1 inhibited the tricarboxylic acid cycle(TCA)pathway and the transporter pathway of NADH to coenzyme Q on the electron transport chain.P-1 significantly reduced succinate dehydrogenase(SDH),malate dehydrogenase(MDH),ATPase,mitochondrial complex enzymes I,II and IV enzyme activities on the electron transport chain,and 5'-triphosphate(ATP),5'-diphosphate(ADP),5'-monophosphate(AMP)content,and energy charge(EC);significantly increased 6-phosphofructokinase(PFK)enzyme activity.The release of Ca^(2+)(OD_(680))from the inner mitochondrial membrane and the openness of the mitochondrial permeability transition pore(MPTP)were analysed,and microscopy was performed following staining of mitochondria with JC-1.The results indicated that P-1 significantly increased the release of Ca^(2+) and the openness of MPTP,decreased the mitochondrial membrane potential,and produced green fluorescence;transcriptomics data analysis showed that there were 39 differentially expressed genes(DEGs)related to energy metabolism enzymes.The results verified by qRT-PCR were basically consistent with the transcriptome sequencing results.Thus,P-1 achieved its inhibitory effect mainly by regulating genes related to energy metabolism.

棉花黄萎病抗菌肽25a2的生物信息学分析(英文)

Protein 25a2 is the antifungal peptide of cotton Verticillium wilt which was isolated from Bacillus amyloliquefaciens. The amino acid sequence of antifungal peptide 25a2 was analyzed using bioinformatics tools, and the characters of signal peptides, transmembrane topological structura, physicochemical signatures, protein domain, secondary and tertiary structure of protein were predicted. The results showed that 25a2 was a secreted protein, the sequence of which included a signal peptide in N end and a transmembrane domain in C end. The predicted secondary structure showed that the antibacterial peptide was mainly free random coils, belonging to mixed protein, three-dimensional model of 25a2 was a compact ball. These results showed that the most possible action mechanism of antifungal peptide 25a2 might be ＂carpet＂ model.