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Evolutionary selective trends of insect/mosquito antimicrobial defensin peptides containing cysteine-stabilized alpha/beta motifs.
Peptides 2007; 28(1):62-75P

Abstract

Insect defensins containing cysteine-stabilized alpha/beta motifs (Cs-alpha/beta defensin) are cationic, inducible antibacterial peptides involved in humoral defence against pathogens. To examine trends in molecular evolution of these antimicrobial peptides, sequences similar to the well-characterized Cs-alpha/beta defensin peptide of Anopheles gambiae, using six cysteine residues as landmarks, were retrieved from genomic and protein databases. These sequences were derived from different orders of insects. Genes of insect Cs-alpha/beta defensin appear to constitute a multigene family in which the copy number varies between insect species. Phylogenetic analysis of these sequences revealed two main lineages, one group comprising mainly lepidopteran insects and a second, comprising Hemiptera, Coleoptera, Diptera and Hymenoptera insects. Moreover, the topology of the phylogram indicated dipteran Cs-alpha/beta defensins are diverse, suggesting diversity in immune mechanisms in this order of insects. Overall evolutionary analysis indicated marked diversification and expansion of mature defensin isoforms within the species of mosquitoes relative to non-mosquito defensins, implying the presence of finely tuned immune responses to counter pathogens. The observed higher synonymous substitution rate relative to the nonsynonymous rate in almost all the regions of Cs-alpha/beta defensin of mosquitoes suggests that these peptides are predominately under purifying selection. The maximum-likelihood models of codon substitution indicated selective pressure at different amino acid sites in mosquito mature Cs-alpha/beta defensins is differ and are undergoing adaptive evolution in comparison to non-mosquito Cs-alpha/beta defensins, for which such selection was inconspicuous; this suggests the acquisition of selective advantage of the Cs-alpha/beta defensins in the former group. Finally, this study represents the most detailed report on the evolutionary strategies of Cs-alpha/beta defensins of mosquitoes in particular and insects in general, and indicates that insect Cs-alpha/beta defensins have evolved by duplication followed by divergence, to produce a diverse set of paralogues.

Authors+Show Affiliations

Department of Chemistry, Faculty of Science, University of Colombo, Sri Lanka. rsdassan@webmail.cmb.ac.lkNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17161505

Citation

Dassanayake, R S., et al. "Evolutionary Selective Trends of Insect/mosquito Antimicrobial Defensin Peptides Containing Cysteine-stabilized Alpha/beta Motifs." Peptides, vol. 28, no. 1, 2007, pp. 62-75.
Dassanayake RS, Silva Gunawardene YI, Tobe SS. Evolutionary selective trends of insect/mosquito antimicrobial defensin peptides containing cysteine-stabilized alpha/beta motifs. Peptides. 2007;28(1):62-75.
Dassanayake, R. S., Silva Gunawardene, Y. I., & Tobe, S. S. (2007). Evolutionary selective trends of insect/mosquito antimicrobial defensin peptides containing cysteine-stabilized alpha/beta motifs. Peptides, 28(1), pp. 62-75.
Dassanayake RS, Silva Gunawardene YI, Tobe SS. Evolutionary Selective Trends of Insect/mosquito Antimicrobial Defensin Peptides Containing Cysteine-stabilized Alpha/beta Motifs. Peptides. 2007;28(1):62-75. PubMed PMID: 17161505.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evolutionary selective trends of insect/mosquito antimicrobial defensin peptides containing cysteine-stabilized alpha/beta motifs. AU - Dassanayake,R S, AU - Silva Gunawardene,Y I N, AU - Tobe,S S, Y1 - 2006/12/11/ PY - 2006/04/24/received PY - 2006/09/11/revised PY - 2006/09/11/accepted PY - 2006/12/13/pubmed PY - 2007/3/27/medline PY - 2006/12/13/entrez SP - 62 EP - 75 JF - Peptides JO - Peptides VL - 28 IS - 1 N2 - Insect defensins containing cysteine-stabilized alpha/beta motifs (Cs-alpha/beta defensin) are cationic, inducible antibacterial peptides involved in humoral defence against pathogens. To examine trends in molecular evolution of these antimicrobial peptides, sequences similar to the well-characterized Cs-alpha/beta defensin peptide of Anopheles gambiae, using six cysteine residues as landmarks, were retrieved from genomic and protein databases. These sequences were derived from different orders of insects. Genes of insect Cs-alpha/beta defensin appear to constitute a multigene family in which the copy number varies between insect species. Phylogenetic analysis of these sequences revealed two main lineages, one group comprising mainly lepidopteran insects and a second, comprising Hemiptera, Coleoptera, Diptera and Hymenoptera insects. Moreover, the topology of the phylogram indicated dipteran Cs-alpha/beta defensins are diverse, suggesting diversity in immune mechanisms in this order of insects. Overall evolutionary analysis indicated marked diversification and expansion of mature defensin isoforms within the species of mosquitoes relative to non-mosquito defensins, implying the presence of finely tuned immune responses to counter pathogens. The observed higher synonymous substitution rate relative to the nonsynonymous rate in almost all the regions of Cs-alpha/beta defensin of mosquitoes suggests that these peptides are predominately under purifying selection. The maximum-likelihood models of codon substitution indicated selective pressure at different amino acid sites in mosquito mature Cs-alpha/beta defensins is differ and are undergoing adaptive evolution in comparison to non-mosquito Cs-alpha/beta defensins, for which such selection was inconspicuous; this suggests the acquisition of selective advantage of the Cs-alpha/beta defensins in the former group. Finally, this study represents the most detailed report on the evolutionary strategies of Cs-alpha/beta defensins of mosquitoes in particular and insects in general, and indicates that insect Cs-alpha/beta defensins have evolved by duplication followed by divergence, to produce a diverse set of paralogues. SN - 0196-9781 UR - https://www.unboundmedicine.com/medline/citation/17161505/Evolutionary_selective_trends_of_insect/mosquito_antimicrobial_defensin_peptides_containing_cysteine_stabilized_alpha/beta_motifs_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0196-9781(06)00490-6 DB - PRIME DP - Unbound Medicine ER -