Novel cathelicidin-derived antimicrobial peptides from Equus asinus.
In the present study, EA-CATH1 and EA-CATH2 were identified from a constructed lung cDNA library of donkey (Equus asinus) as members of cathelicidin-derived antimicrobial peptides, using a nested PCR-based cloning strategy. Composed of 25 and 26 residues, respectively, EA-CATH1 and EA-CATH2 are smaller than most other cathelicidins and have no sequence homology to other cathelicidins identified to date. Chemically synthesized EA-CATH1 exerted potent antimicrobial activity against most of the 32 strains of bacteria and fungi tested, especially the clinically isolated drug-resistant strains, and minimal inhibitory concentration values against Gram-positive bacteria were mostly in the range of 0.3-2.4 microg mL(-1). EA-CATH1 showed an extraordinary serum stability and no haemolytic activity against human erythrocytes in a dose up to 20 microg mL(-1). CD spectra showed that EA-CATH1 mainly adopts an alpha-helical conformation in a 50% trifluoroethanol/water solution, but a random coil in aqueous solution. Scanning electron microscope observations of Staphylococcus aureus (ATCC2592) treated with EA-CATH1 demonstrated that EA-CATH could cause rapid disruption of the bacterial membrane, and in turn lead to cell lysis. This might explain the much faster killing kinetics of EA-CATH1 than conventional antibiotics revealed by killing kinetics data. In the presence of CaCl(2), EA-CATH1 exerted haemagglutination activity, which might potentiate an inhibition against the bacterial polyprotein interaction with the host erythrocyte surface, thereby possibly restricting bacterial colonization and spread.
Lu
Zekuan
Z
College of Life Sciences, Hebei Normal University, Shijiazhuang, China.
Wang
Yipeng
Y
Zhai
Lei
L
Che
Qiaolin
Q
Wang
Hui
H
Du
Shuyuan
S
Wang
Duo
D
Feng
Feifei
F
Liu
Jingze
J
Lai
Ren
R
Yu
Haining
H
D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D001798:Blood Proteins / Q000235:genetics; D002122:Calcium Chloride / Q000494:pharmacology; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D018397:Equidae / Q000235:genetics*; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects; D005658:Fungi / Q000187:drug effects; D015723:Gene Library; D006089:Gram-Negative Anaerobic Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006384:Hemagglutination / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D011498:Protein Precursors / Q000235:genetics; D017433:Protein Structure, Secondary; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D044967:Serum / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects / Q000648:ultrastructure; D054804:Cathelicidins
D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D018076:DNA, Complementary; D011498:Protein Precursors; C121625:cathelicidin 2 protein, mammal; D002122:Calcium Chloride; D054804:Cathelicidins