Dicynthaurin: an antimicrobial peptide from hemocytes of the solitary tunicate, Halocynthia aurantium.
We isolated a novel antimicrobial peptide, dicynthaurin, from hemocytes of a tunicate, Halocynthia aurantium. The native peptide had a mass of approximately 6.2 kDa and was composed of two 30-residue monomers without sequence homology to any previously identified peptides (ILQKAVLDCLKAAGSSLSKAAITAIYNKIT). Most cynthaurin molecules were C-terminally amidated and were linked covalently by a single cystine disulfide bond. When performed in membrane-mimetic environments, circular dichroism studies of dicynthaurin revealed largely alpha-helical conformations. Dicynthaurin's broad-spectrum activity encompassed Gram-positive (Micrococcus luteus, Staphylococcus aureus, Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), but not Candida albicans, a fungus. Although dicynthaurin was purified from a marine invertebrate, its antimicrobial activity was optimal at NaCl concentrations below 100 mM. This suggests that the antimicrobial actions of this molecule may take place intracellularly (e.g., within a phagosome) rather than extracellularly.
Lee
I H
IH
Department of Life Science, Hoseo University, Asan City, Chungnam-Do, South Korea. leeih@office.hoseo.ac.kr
Lee
Y S
YS
Kim
C H
CH
Kim
C R
CR
Hong
T
T
Menzel
L
L
Boo
L M
LM
Pohl
J
J
Sherman
M A
MA
Waring
A
A
Lehrer
R I
RI
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification*; D002942:Circular Dichroism; D019281:Dimerization; D004151:Dipeptides / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification*; D006434:Hemocytes / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014020:Tissue Extracts / Q000737:chemistry; D014561:Urochordata / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D004151:Dipeptides; D010455:Peptides; D014020:Tissue Extracts; C437228:dicynthaurin