TY - JOUR
T1 - Peptide defenses of the Cascades frog Rana cascadae
T2 - implications for the evolutionary history of frogs of the Amerana species group
AU - Conlon, J. Michael
AU - al-Dhaheri, Ahmed
AU - al-Mutawa, Eissa
AU - al-Kharrge, Rokaya
AU - Ahmed, Eman
AU - Kolodziejek, Jolanta
AU - Nowotny, Norbert
AU - Nielsen, Per F.
AU - Davidson, Carlos
PY - 2007/6
Y1 - 2007/6
N2 - The Cascades frog Rana cascadae belongs to the Amerana (or Rana boylii) group that includes six additional species from western North America (R. aurora, R. boylii, R. draytonii, R. luteiventris, R. muscosa, and R. pretiosa). R. cascadae is particularly susceptible to pathogenic microorganisms in the environment and populations have declined precipitously in parts of its range so that the protection afforded by dermal antimicrobial peptides may be crucial to survival of the species. Peptidomic analysis of norepinephrine-stimulated skin secretions led to the identification of six peptides with differential cytolytic activities that were present in high abundance. Structural characterization showed that they belonged to the ranatuerin-2 (one peptide), brevinin-1 (one peptide), and temporin (four peptides) families. Ranatuerin-2CSa (GILSSFKGVAKGVAKDLAGKLLETLKCKITGC) and brevinin-1CSa (FLPILAGLAAKIVPKLFCLATKKC) showed broad spectrum antibacterial activity (MIC ≤ 32 μM against Escherichia coli and Staphylococcus aureus) but only brevinin-1CSa was strongly hemolytic against human erythrocytes (LC50 = 5 μM). The taxonomy of ranid frogs is currently in a considerable state of flux. The ranatuerin-2 gene is expressed in all members of the Amerana group studied to-date and cladistic analysis based upon a comparison of the amino acid sequences of this peptide indicates that R. cascadae, R. muscosa and R. aurora form a clade that is distinct from one containing R. draytonii, R. boylii, and R. luteiventris. This conclusion is consistent with previous analyses based upon comparisons of the nucleotide sequences of mitochondrial genes.
AB - The Cascades frog Rana cascadae belongs to the Amerana (or Rana boylii) group that includes six additional species from western North America (R. aurora, R. boylii, R. draytonii, R. luteiventris, R. muscosa, and R. pretiosa). R. cascadae is particularly susceptible to pathogenic microorganisms in the environment and populations have declined precipitously in parts of its range so that the protection afforded by dermal antimicrobial peptides may be crucial to survival of the species. Peptidomic analysis of norepinephrine-stimulated skin secretions led to the identification of six peptides with differential cytolytic activities that were present in high abundance. Structural characterization showed that they belonged to the ranatuerin-2 (one peptide), brevinin-1 (one peptide), and temporin (four peptides) families. Ranatuerin-2CSa (GILSSFKGVAKGVAKDLAGKLLETLKCKITGC) and brevinin-1CSa (FLPILAGLAAKIVPKLFCLATKKC) showed broad spectrum antibacterial activity (MIC ≤ 32 μM against Escherichia coli and Staphylococcus aureus) but only brevinin-1CSa was strongly hemolytic against human erythrocytes (LC50 = 5 μM). The taxonomy of ranid frogs is currently in a considerable state of flux. The ranatuerin-2 gene is expressed in all members of the Amerana group studied to-date and cladistic analysis based upon a comparison of the amino acid sequences of this peptide indicates that R. cascadae, R. muscosa and R. aurora form a clade that is distinct from one containing R. draytonii, R. boylii, and R. luteiventris. This conclusion is consistent with previous analyses based upon comparisons of the nucleotide sequences of mitochondrial genes.
KW - Antimicrobial
KW - Brevinin-1
KW - Frog skin
KW - Peptidomics
KW - Ranatuerin-2
KW - Temporin
UR - http://www.scopus.com/inward/record.url?scp=34249729913&partnerID=8YFLogxK
U2 - 10.1016/j.peptides.2007.03.010
DO - 10.1016/j.peptides.2007.03.010
M3 - Article
C2 - 17451843
AN - SCOPUS:34249729913
SN - 0196-9781
VL - 28
SP - 1268
EP - 1274
JO - Peptides
JF - Peptides
IS - 6
ER -