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BMC Genomics Apr 2017β-defensins are small, cationic, antimicrobial peptides found in species across the plant and animal kingdoms. In addition to microbiocidal activity, roles in immunity... (Comparative Study)
Comparative Study
BACKGROUND
β-defensins are small, cationic, antimicrobial peptides found in species across the plant and animal kingdoms. In addition to microbiocidal activity, roles in immunity as well as reproduction have more recently been documented. β-defensin genes in Ovis aries (domestic sheep) have been poorly annotated, having been identified only by automatic gene prediction algorithms. The objective of this study was to use a comparative genomics approach to identify and characterise the β-defensin gene repertoire in sheep using the bovine genome as the primary reference.
RESULTS
All 57 currently predicted bovine β-defensin genes were used to find orthologous sequences in the most recent version of the sheep genome (OAR v4.0). Forty three genes were found to have close genomic matches (>70% similarity) between sheep and cattle. The orthologous genes were located in four clusters across the genome, with 4 genes on chromosome 2, 19 genes on chromosome 13, 5 genes on chromosome 20 and 15 genes on chromosome 26. Conserved gene order for the β-defensin genes was apparent in the two smaller clusters, although gene order was reversed on chromosome 2, suggesting an inversion between sheep and cattle. Complete conservation of gene order was also observed for chromosome 13 β-defensin orthologs. More structural differences were apparent between chromosome 26 genes and the orthologous region in the bovine reference genome, which is known to be copy-number variable. In this cluster, the Defensin-beta 1 (DEFB1) gene matched to eleven Bovine Neutrophil beta-Defensin (BNBD) genes on chromosome 27 with almost uniform similarity, as well as to tracheal, enteric and lingual anti-microbial peptides (TAP, EAP and LAP), suggesting that annotation of the bovine reference sequence is still incomplete. qPCR was used to profile the expression of 34 β-defensin genes, representing each of the four clusters, in the ram reproductive tract. Distinct site-specific and differential expression profiles were detected across the reproductive tract of mature rams with preferential β-defensin gene expression in the epididymis, recapitulating observations for orthologous genes in other species.
CONCLUSIONS
This is the first comprehensive analysis of β-defensin genes encoded by the ovine reference sequence, and the first report of an expanded repertoire of β-defensin genes in this species. The preferential expression of these genes in the epididymis suggests a role in fertility, possibly providing immunoprotection for sperm within the female reproductive tract.
Topics: Amino Acid Sequence; Animals; Chromosome Mapping; Gene Expression; Male; Multigene Family; Phylogeny; Sequence Analysis, DNA; Sheep, Domestic; Testis; beta-Defensins
PubMed: 28376793
DOI: 10.1186/s12864-017-3666-x -
PloS One 2020Plant defensins possess diverse biological functions that include antifungal and antibacterial activities and α-amylase and trypsin inhibitory properties. Two...
Plant defensins possess diverse biological functions that include antifungal and antibacterial activities and α-amylase and trypsin inhibitory properties. Two mutations, G9R and V39R, were confirmed to increase the antifungal activity of Raphanus sativus antifungal protein 2 (RsAFP2). Accelerated Molecular Dynamics (aMD) were carried out to examine the conformational changes present in these RsAFP2 mutants, and its two closest homologs compared to the wild-type protein. Specifically, the root mean square fluctuation values for the eight cysteine amino acids involved in the four disulfide bonds were low in the V39R mutant compared to the wild-type. Additionally, analysis of the free energy change revealed that G9R and V39R mutations exert a neutral and stabilizing effect on RsAFP2 conformation, and this is supported by the observed lower total energy of mutants compared to the wild-type, suggesting that enhanced stability of the mutants. However, MD simulations to a longer time scale would aid in capturing more conformational state of the wild-type and mutants defensin protein. Furthermore, the aMD simulations on fungal mimic membranes with RsAFP2 and its mutants and homologs showed that the mutant proteins caused higher deformation and water diffusion than the native RsAFP2, especially the V39R mutant. The mutant variants seem to interact by specifically targeting the POPC and POPI lipids amongst others. This work highlights the stabilizing effect of mutations at the 9th and 39th positions of RsAFP2 and their increased membrane deformation activity.
Topics: Amino Acid Sequence; Defensins; Deuterium; Molecular Dynamics Simulation; Molecular Sequence Data; Mutation; Sequence Alignment; Sequence Homology, Amino Acid
PubMed: 33253167
DOI: 10.1371/journal.pone.0241679 -
Infection and Immunity Jun 2014Mammalian α-defensins are approximately 4- to 5-kDa broad-spectrum antimicrobial peptides and abundant granule constituents of neutrophils and small intestinal Paneth...
Mammalian α-defensins are approximately 4- to 5-kDa broad-spectrum antimicrobial peptides and abundant granule constituents of neutrophils and small intestinal Paneth cells. The bactericidal activities of amphipathic α-defensins depend in part on electropositive charge and on hydrophobic amino acids that enable membrane disruption by interactions with phospholipid acyl chains. Alignment of α-defensin primary structures identified conserved hydrophobic residues in the loop formed by the Cys(III)-Cys(V) disulfide bond, and we have studied their role by testing the effects of mutagenesis on bactericidal activities. Mouse α-defensin 4 (Crp-4) and rhesus myeloid α-defensin 4 (RMAD-4) were selected for these studies, because they are highly bactericidal in vitro and have the same overall electropositive charge. Elimination of hydrophobicity by site-directed mutagenesis at those positions in Crp-4 attenuated bactericidal activity markedly. In contrast to native Crp-4, the (I23/F25/L26/G)-Crp-4 variant lacked bactericidal activity against Salmonella enterica serovar Typhimurium and did not permeabilize Escherichia coli ML35 cells as a result of removing aliphatic side chains by Gly substitutions. Ala replacements in (I23/F25/L26/A)-Crp-4 restored activity, evidence that hydrophobicity contributed by Ala methyl R-groups was sufficient for activity. In macaques, neutrophil α-defensin RMAD-6 is identical to RMAD-4, except for a F28S difference, and (F28S)-RMAD-4 mutagenesis attenuated RMAD-4 bactericidal activity and E. coli permeabilization. Interestingly, (R31/32D)-Crp-4 lacks activity in these assays despite the presence of the Ile23, Phe25, and Leu26 hydrophobic patch. We infer that electrostatic interactions between cationic α-defensin residues and negative charge on bacteria precede interactions between critical hydrophobic residue positions that mediate membrane disruption and bacterial cell killing.
Topics: Amino Acid Substitution; Animals; Bacteria; Cell Membrane Permeability; Cells, Cultured; Hydrophobic and Hydrophilic Interactions; Macaca mulatta; Mice; Mutagenesis, Site-Directed; Recombinant Proteins; alpha-Defensins
PubMed: 24614658
DOI: 10.1128/IAI.01414-13 -
International Journal of Molecular... Dec 2020Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins may act against pathogenic microorganisms either directly (by binding and...
Defensins are small and rather ubiquitous cysteine-rich anti-microbial peptides. These proteins may act against pathogenic microorganisms either directly (by binding and disrupting membranes) or indirectly (as signaling molecules that participate in the organization of the cellular defense). Even though defensins are widespread across eukaryotes, still, extensive nucleotide and amino acid dissimilarities hamper the elucidation of their response to stimuli and mode of function. In the current study, we screened the genome for the identification of defensin genes, predicted the relating protein structures, and further studied their transcriptional responses to biotic (, , , and infections) and abiotic (cold stress) stimuli. Tomato defensin sequences were classified into two groups (C8 and C12). Our data indicate that the transcription of defensin coding genes primarily depends on the specific pathogen recognition patterns of and . The immunodetection of plant defensin 1 protein was achieved only in the roots of plants inoculated with In contrast, the almost null effects of viral infections and cold stress, and the failure to substantially induce the gene transcription suggest that these factors are probably not primarily targeted by the tomato defensin network.
Topics: Animals; Cold-Shock Response; Defensins; Gene Expression Regulation, Plant; Host-Pathogen Interactions; Solanum lycopersicum; Plant Proteins; Transcriptional Activation; Tylenchoidea; Verticillium
PubMed: 33317090
DOI: 10.3390/ijms21249380 -
Biochimica Et Biophysica Acta Sep 2006A group of interesting molecules called defensins exhibit multiple functions but have been primarily recognized to possess a broad spectrum of antimicrobial activities.... (Review)
Review
A group of interesting molecules called defensins exhibit multiple functions but have been primarily recognized to possess a broad spectrum of antimicrobial activities. Studies have reported two different types of defensins (alpha and beta) from human and animals, a cyclic theta defensin from rhesus, and several defensin-like peptides from plants. There is no amino acid sequence homology between these peptides, but they all contain three Cys-Cys disulfide linkages while the connectivities are different. Human beta-defensin-3 (HbetaD-3) is the most recently discovered member of the host-defense peptide family that has attracted much attention. This molecule is expressed either constitutively or induced upon a challenge, and a growing evidence indicates the involvement of such molecules in adaptive immunity as well. It has been shown to exhibit antibacterial activities towards Gram-negative and Gram-positive bacteria as well as an ability to act as a chemo-attractant. Analysis of NMR structural data suggested a symmetrical dimeric form of this peptide in solution, which consists of three beta strands and a short helix in the N-terminal region. While the disulfide linkages are known to provide the structural stability and stability against proteases, the biological relevance of this dimeric form was contradicted by another biological study. Since there is considerable current interest in developing HbetaD-3 for possible pharmaceutical applications, studies to further our understanding on the determinants of antibacterial activities and immunomodulatory function of HbetaD-3 are considered to be highly significant. The knowledge of its biosynthetic regulation will also help in understanding the role of HbetaD-3 in immunity. This article presents an overview of the expression and regulation of HbetaD-3 in humans, and the structure-function correlations among HbetaD-3 and its modified peptides are discussed emphasizing the functional importance. The future scope for studies on HbetaD-3 and design of short potent antimicrobial peptides, based on the native HbetaD-3 molecule, that do not interfere in the immunomodulatory function is also outlined.
Topics: Amino Acid Sequence; Anti-Infective Agents; Disease; Humans; Molecular Sequence Data; Sequence Homology, Amino Acid; Structure-Activity Relationship; beta-Defensins
PubMed: 16978580
DOI: 10.1016/j.bbamem.2006.07.007 -
International Journal of Molecular... Jul 2014An important member of the defensin family, β-defensin 2, is believed to play an important role in defense against foreign pathogens. In the present study, we...
An important member of the defensin family, β-defensin 2, is believed to play an important role in defense against foreign pathogens. In the present study, we constructed lentiviral vectors to express and knockdown β-defensin 2 in rat lungs. The results showed that the infection of β-defensin 2 overexpression lentivirus and β-defensin 2 shRNA effectively increased and suppressed the expression of β-defensin 2 in rat lung, respectively. The overexpression of β-defensin 2 mediated by the lentiviral vector protected lung from infection of Pseudomonas aeruginosa, but shRNA targeting β-defensin 2 aggregated the damage of lung. In addition, we also found that β-defensin 2 overexpression increased basal expression of anti-inflammatory cytokine such as IL-4, IL-10 and IL-13 and decreased levels of proinflammatory cytokines which include IL-1α, IL-1β, IL-5, IL-6, IL-8, IL-18, and TNF-α. Moreover, in the process of cytokine regulation, NF-κB pathway may be involved. Taken together, these data suggest that β-defensin 2 has protective effects against infection of Pseudomonas aeruginosa in rat and plays a role in inflammatory regulation by adjusting cytokine levels.
Topics: Animals; Bronchoalveolar Lavage Fluid; Cytokines; Female; Lung Injury; Male; NF-kappa B; Pseudomonas Infections; Pseudomonas aeruginosa; RNA Interference; RNA, Messenger; RNA, Small Interfering; Rats; Rats, Sprague-Dawley; Signal Transduction; beta-Defensins
PubMed: 25079443
DOI: 10.3390/ijms150813372 -
PloS One 2016Beta-defensins are important part of innate immunity of fish, which are the first defense line against invading pathogens. In this study, the β-defensin (Lhβ-defensin)...
Beta-defensins are important part of innate immunity of fish, which are the first defense line against invading pathogens. In this study, the β-defensin (Lhβ-defensin) gene was cloned from spleen tissue of soiny mullet (Liza haematocheila). Lhβ-defensin cDNA was 747 bp in length, encoding 63 amino acids. Sequence alignment revealed that Lhβ-defensin contained six conserved cysteine residues and shared 97.5% sequence identities with grouper (Epinephelus coioides) β-defensin. Realtime PCR revealed that Lhβ-defensin was highest expressed in the immune related organs, such as spleen, kidney and gut of healthy fish. Following Streptococcus dysgalactiae infection, Lhβ-defensin was up-regulated in immune related organs, e.g. 17.6-fold in spleen and 10.87-fold in gut at 24 h post infection (hpi). Lhβ-defensin possessed a monomeric structure of a three-stranded anti-parallel β-sheet and an α-helix stabilized by three disulfide bonds formed by Cys30-Cys58, Cys36-Cys52, and Cys40-Cys59. In addition to the experimental work, computer simulation was also carried out to determine the possible conformation of β-defensin and its interaction with palmitoyloleoylphosphatidylglycerol (POPG), a model of bacteria membrane. The Lhβ-defensin was found to form dimeric structure stabilized by the van der Waals contacts of Leu35 and Cys37 in two anti-parallel β1-strands and the cation-π interaction between Tyr32 and Arg54 respectively in the two β1-strands. The most important interactions between β-defensin and membrane are the electrostatic interactions between Arg residues in β-defensin and head group of POPG bilayer as well as hydrogen bond interactions between them. Our results were useful for further understanding the potential mechanism of antimicrobial property of fish β-defensins.
Topics: Amino Acid Sequence; Animals; Anti-Bacterial Agents; Cloning, Molecular; Gene Expression Regulation; Organ Specificity; Phylogeny; Protein Multimerization; Sequence Alignment; Smegmamorpha; Streptococcal Infections; Streptococcus; Water; beta-Defensins
PubMed: 27322675
DOI: 10.1371/journal.pone.0157544 -
International Journal of Molecular... Sep 2022Common bed bugs, , can carry, but do not transmit, pathogens to the vertebrate hosts on which they feed. Some components of the innate immune system of bed bugs, such as...
Common bed bugs, , can carry, but do not transmit, pathogens to the vertebrate hosts on which they feed. Some components of the innate immune system of bed bugs, such as antimicrobial peptides (AMPs), eliminate the pathogens. Here, we determined the molecular characteristics, structural properties, and phylogenetic relatedness of two new defensins (CL-defensin1 (XP_024085718.1), CL-defensin2 (XP_014240919.1)), and two new defensin isoforms (CL-defensin3a (XP_014240918.1), CL-defensin3b (XP_024083729.1)). The complete amino acid sequences of CL-defensin1, CL-defensin2, CL-defensin3a, and CL-defensin3b are strongly conserved, with only minor differences in their signal and pro-peptide regions. We used a combination of comparative transcriptomics and real-time quantitative PCR to evaluate the expression of these defensins in the midguts and the rest of the body of insects that had been injected with bacteria or had ingested blood containing the Gram-positive (Gr+) bacterium and the Gram-negative (Gr-) bacterium . We demonstrate, for the first time, sex-specific and immunization mode-specific upregulation of bed bug defensins in response to injection or ingestion of Gr+ or Gr- bacteria. Understanding the components, such as these defensins, of the bed bugs' innate immune systems in response to pathogens may help unravel why bed bugs do not transmit pathogens to vertebrates.
Topics: Animals; Antimicrobial Peptides; Bacteria; Bedbugs; Defensins; Eating; Female; Male; Phylogeny; Protein Isoforms
PubMed: 36232802
DOI: 10.3390/ijms231911505 -
The expression of human alpha and beta defensin in the endometrium and their effect on implantation.Journal of Assisted Reproduction and... Nov 2007Alpha and beta defensins have been isolated from various human tissues and form an important part of the innate immune system. Their role in implantation of the embryo...
BACKGROUND
Alpha and beta defensins have been isolated from various human tissues and form an important part of the innate immune system. Their role in implantation of the embryo has not yet been studied. This study was designed to detect both alpha and beta defensins in the mid luteal phase endometrium and investigate the correlation between the defensin expression and implantation of the embryo.
METHOD AND RESULTS
An experimental study was designed to detect alpha defensin (HNP1-3) and beta defensin (HBD1) in midluteal phase endometrial samples obtained from women attending the IVF unit at the Liverpool Women's Hospital, UK. Samples were obtained at least two menstrual cycles before IVF treatment was commenced. Immunohistochemical staining was conducted to estimate defensin expression. Some endometrial stromal cells stained positive for HNP1-3 during the midluteal phase. HNP1-3 expression is significantly higher in cases presenting with female factor infertility as compared with purely male factor infertility. A significant increase was not observed in tubal factor or endometriosis when considered separately. Endometrial stromal neutrophils were shown to be the main source of endometrial HNP1-3. HBD1 was the only beta defensin detected by immunochemical staining in the midluteal phase endometrium. The intensity of staining was significantly different in the endometrial stroma, luminal and glandular epithelia. HBD1 expression is not significantly higher in female factor infertility.
CONCLUSION
The study confirmed secretion of HNP1-3 by endometrial stromal neutrophils. Glandular epithelium is the main source of HBD1 expression in the human endometrium. HNP1-3 shows increased expression in female factor infertility. HBD1 expression is not higher in female factor infertility. These defensins do not appear to influence implantation.
Topics: Adult; Embryo Implantation; Endometrium; Female; Gene Expression; Humans; Immunohistochemistry; Infertility, Female; Infertility, Male; Male; alpha-Defensins; beta-Defensins
PubMed: 18026831
DOI: 10.1007/s10815-007-9173-2 -
Cellular and Molecular Life Sciences :... Jul 2011Primate theta-defensins are physically distinguished as the only known fully-cyclic peptides of animal origin. Humans do not produce theta-defensin peptides due to a... (Review)
Review
Primate theta-defensins are physically distinguished as the only known fully-cyclic peptides of animal origin. Humans do not produce theta-defensin peptides due to a premature stop codon present in the signal sequence of all six theta-defensin pseudogenes. Instead, since the putative coding regions of human theta-defensin pseudogenes have remained remarkably intact, their corresponding peptides, called "retrocyclins", have been recreated using solid-phase synthetic approaches. Retrocyclins exhibit an exceptional therapeutic index both as inhibitors of HIV-1 entry and as bactericidal agents, which makes retrocyclins promising candidates for further development as topical microbicides to prevent sexually transmitted diseases. This review presents the evolution, antiretroviral mechanism of action, and potential clinical applications of retrocyclins to prevent sexual transmission of HIV-1.
Topics: Defensins; HIV Infections; HIV-1; Humans; Virus Internalization
PubMed: 21553001
DOI: 10.1007/s00018-011-0715-5