Beta-defensin 2: Difference between revisions

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{{Infobox_gene}}
{{Infobox_gene}}
'''Beta-defensin 2''' (BD-2) also known as '''skin-antimicrobial peptide 1''' (SAP1) is a [[peptide]] that in humans is encoded by the ''DEFB4'' (defensin, beta 4) [[gene]].<ref name="pmid9202117">{{cite journal | vauthors = Harder J, Bartels J, Christophers E, Schroder JM | title = A peptide antibiotic from human skin | journal = Nature | volume = 387 | issue = 6636 | pages = 861 |date=Jul 1997 | pmid = 9202117 | pmc =  | doi = 10.1038/43088 }}</ref>
'''Beta-defensin 2''' (BD-2) also known as '''skin-antimicrobial peptide 1''' (SAP1) is a [[peptide]] that in humans is encoded by the ''DEFB4'' (defensin, beta 4) [[gene]].<ref name="pmid9202117">{{cite journal | vauthors = Harder J, Bartels J, Christophers E, Schröder JM | title = A peptide antibiotic from human skin | journal = Nature | volume = 387 | issue = 6636 | pages = 861 | date = June 1997 | pmid = 9202117 | pmc =  | doi = 10.1038/43088 }}</ref>


Human beta-defensin-2 (hBD-2) is a cysteine-rich cationic low molecular weight antimicrobial peptide recently discovered in lesional skin.
Human beta-defensin-2 (hBD-2) is a cysteine-rich cationic low molecular weight antimicrobial peptide recently discovered in lesional skin.
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== Structure ==
== Structure ==


hBD-2 is a protein whose primary structure is made by 64 aminoacids. At concentrations ≤2.4 mM, hBD-2 is monomeric.<ref>{{cite journal | vauthors = Sawai MV, Jia HP, Liu L, Aseyev V, Wiencek JM, ((McCray PB Jr)), Ganz T, Kearney WR, Tack BF | title = The NMR structure of human beta-defensin-2 reveals a novel alpha-helical segment. | journal = Biochemistry | volume = 40 | issue = 13 | pages = 3810–3816 | year = 2001 |pmid = 11300761 | pmc =  | doi = 10.1021/bi002519d }}</ref> The structure is [[amphiphilic]] with a nonuniform surface distribution of positive charge and contains several key structural elements, including a triple-stranded, antiparallel [[beta sheet]] with strands 2 and 3 in a [[beta hairpin]] conformation.  
hBD-2 is a protein whose primary structure is made by 64 aminoacids. At concentrations ≤2.4 mM, hBD-2 is monomeric.<ref>{{cite journal | vauthors = Sawai MV, Jia HP, Liu L, Aseyev V, Wiencek JM, McCray PB, Ganz T, Kearney WR, Tack BF | title = The NMR structure of human beta-defensin-2 reveals a novel alpha-helical segment | journal = Biochemistry | volume = 40 | issue = 13 | pages = 3810–6 | date = April 2001 | pmid = 11300761 | pmc =  | doi = 10.1021/bi002519d }}</ref> The structure is [[amphiphilic]] with a nonuniform surface distribution of positive charge and contains several key structural elements, including a triple-stranded, antiparallel [[beta sheet]] with strands 2 and 3 in a [[beta hairpin]] conformation.  
The determination of other structural elements depends on the technique used. When X-ray crystallography is used an [[alpha helix]] can be observed at the [[C-terminus|C-terminal]] end of the protein (PDB code: {{PDB2|1fd3}}). When using NMR this alpha-helix does not appear (PDB code: {{PDB2|1e4q}}).
The determination of other structural elements depends on the technique used. When X-ray crystallography is used an [[alpha helix]] can be observed at the [[N-terminus|N-terminal]] end of the protein (PDB codes: {{PDB2|1fd3}},{{PDB2|1fd4}}, and {{PDB2|6cs9}}). When using NMR this alpha-helix does not appear (PDB code: {{PDB2|1e4q}}), however this structure was determined using a truncated version of hBD-2 which was missing the initial 4 amino acids, and may be the reason for the discrepancy.


== Function ==
== Function ==


[[Defensin]]s form a family of microbicidal and [[cytotoxic]] peptides made by [[neutrophil]]s. Members of the defensin family are highly similar in protein sequence. Beta-defensin 2 is an antibiotic peptide which is locally regulated by [[inflammation]].<ref>{{cite web | title = Entrez Gene: DEFB4 defensin, beta 4| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=1673| accessdate = }}</ref>
[[Defensin]]s form a family of microbicidal and [[cytotoxic]] peptides made by [[neutrophil]]s. Members of the defensin family are highly similar in protein sequence. Beta-defensin 2 is an antibiotic peptide which is locally regulated by [[inflammation]].<ref>{{cite web | title = Entrez Gene: DEFB4 defensin, beta 4| url = https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=1673| access-date = }}</ref>


Human beta-defensin 2 is produced by a number of [[epithelium|epithelial]] cells and exhibits potent antimicrobial activity against [[Gram-negative bacteria]] and ''[[Candida (genus)|Candida]]'', but not Gram-positive ''[[Staphylococcus aureus|S. aureus]]''.  It has been speculated that beta-defensin 2 may contribute to the infrequency of Gram-negative infections on skin and lung tissue.<ref name="pmid10404637">{{cite journal | vauthors = Schröder JM, Harder J | title = Human beta-defensin-2 | journal = Int. J. Biochem. Cell Biol. | volume = 31 | issue = 6 | pages = 645–51 |date=June 1999 | pmid = 10404637 | doi = 10.1016/S1357-2725(99)00013-8 | url = | issn = }}</ref>
Human beta-defensin 2 is produced by a number of [[epithelium|epithelial]] cells and exhibits potent antimicrobial activity against [[Gram-negative bacteria]] and ''[[Candida (genus)|Candida]]'', but not Gram-positive ''[[Staphylococcus aureus|S. aureus]]''.  It has been speculated that beta-defensin 2 may contribute to the infrequency of Gram-negative infections on skin and lung tissue.<ref name="pmid10404637">{{cite journal | vauthors = Schröder JM, Harder J | title = Human beta-defensin-2 | journal = The International Journal of Biochemistry & Cell Biology | volume = 31 | issue = 6 | pages = 645–51 | date = June 1999 | pmid = 10404637 | doi = 10.1016/S1357-2725(99)00013-8 }}</ref>


hBD-2 represents the first human defensin that is produced following stimulation of epithelial cells by contact with microorganisms such as ''[[Pseudomonas aeruginosa|P. aeruginosa]]'' or cytokines such as TNF-alpha and IL-1 beta. The HBD-2 gene and protein are locally expressed in [[keratinocytes]] associated with inflammatory skin lesions. It is intriguing to speculate that HBD-2 is a dynamic component of the local epithelial defense system of the skin and respiratory tract having a role to protect surfaces from infection, and providing a possible reason why skin and lung infections with Gram-negative bacteria are rather rare.<ref name="pmid10404637"/>
hBD-2 represents the first human defensin that is produced following stimulation of epithelial cells by contact with microorganisms such as ''[[Pseudomonas aeruginosa|P. aeruginosa]]'' or cytokines such as TNF-alpha and IL-1 beta. The HBD-2 gene and protein are locally expressed in [[keratinocytes]] associated with inflammatory skin lesions. It is intriguing to speculate that HBD-2 is a dynamic component of the local epithelial defense system of the skin and respiratory tract having a role to protect surfaces from infection, and providing a possible reason why skin and lung infections with Gram-negative bacteria are rather rare.<ref name="pmid10404637"/>


Although this protein doesn’t have any antibacterial activity against Gram-positive bacteria, there is a study showing that there is a synergy between hBD-2 and other proteins.<ref name="pmid20485435">{{cite journal | author = Tadayuki Iwase |author2=Yoshio Uehara |author3=Hitomi Shinji |author4=Akiko Tajima |author5=Hiromi Seo |author6=Koji Takada |author7=Toshihiko Agata |author8=Yoshimitsu Mizunoe | title = "Staphylococcus epidermidis Esp inhibits Staphylococcus aureus biofilm formation and nasal colonization".  | journal = Nature | volume = 465 | issue = 7296 | pages = 346–349 | year = 2010 |pmid = 20485435 | doi = 10.1038/nature09074 | url = | issn = }}</ref> One example of this synergistic effect is with epiP, a protein segregated by some strains of ''[[Staphylococcus epidermidis|S. epidermidis]]''. hBD2, holding hands with epiP, is capable of killing ''[[Staphylococcus aureus|S. aureus]]'', a Gram-positive bacteria responsible of human diseases.
Although this protein doesn’t have any antibacterial activity against Gram-positive bacteria, there is a study showing that there is a synergy between hBD-2 and other proteins.<ref name="pmid20485435">{{cite journal | vauthors = Iwase T, Uehara Y, Shinji H, Tajima A, Seo H, Takada K, Agata T, Mizunoe Y | title = Staphylococcus epidermidis Esp inhibits Staphylococcus aureus biofilm formation and nasal colonization | journal = Nature | volume = 465 | issue = 7296 | pages = 346–9 | date = May 2010 | pmid = 20485435 | doi = 10.1038/nature09074 }}</ref> One example of this synergistic effect is with epiP, a protein segregated by some strains of ''[[Staphylococcus epidermidis|S. epidermidis]]''. hBD2, holding hands with epiP, is capable of killing ''[[Staphylococcus aureus|S. aureus]]'', a Gram-positive bacteria responsible of human diseases.


==References==
== References ==
{{reflist}}
{{reflist}}


==External links==
== External links ==
* {{UCSC gene info|DEFB4A}}
* {{UCSC gene info|DEFB4A}}


==Further reading==
== Further reading ==
{{refbegin | 2}}
{{refbegin | 2}}
*{{cite journal | vauthors=Weinberg A, Krisanaprakornkit S, Dale BA |title=Epithelial antimicrobial peptides: review and significance for oral applications. |journal=Crit. Rev. Oral Biol. Med. |volume=9 |issue= 4 |pages= 399–414 |year= 1999 |pmid= 9825219 |doi=10.1177/10454411980090040201 }}
* {{cite journal | vauthors = Weinberg A, Krisanaprakornkit S, Dale BA | title = Epithelial antimicrobial peptides: review and significance for oral applications | journal = Critical Reviews in Oral Biology and Medicine | volume = 9 | issue = 4 | pages = 399–414 | year = 1999 | pmid = 9825219 | doi = 10.1177/10454411980090040201 }}
*{{cite journal | vauthors=Schröder JM, Harder J |title=Human beta-defensin-2. |journal=Int. J. Biochem. Cell Biol. |volume=31 |issue= 6 |pages= 645–51 |year= 1999 |pmid= 10404637 |doi=10.1016/S1357-2725(99)00013-8 }}
* {{cite journal | vauthors = Schröder JM, Harder J | title = Human beta-defensin-2 | journal = The International Journal of Biochemistry & Cell Biology | volume = 31 | issue = 6 | pages = 645–51 | date = June 1999 | pmid = 10404637 | doi = 10.1016/S1357-2725(99)00013-8 }}
*{{cite journal | vauthors=Bals R, Wang X, Wu Z |title=Human beta-defensin 2 is a salt-sensitive peptide antibiotic expressed in human lung. |journal=J. Clin. Invest. |volume=102 |issue= 5 |pages= 874–80 |year= 1998 |pmid= 9727055 |doi=10.1172/JCI2410 |pmc=508952|display-authors=etal}}
* {{cite journal | vauthors = Bals R, Wang X, Wu Z, Freeman T, Bafna V, Zasloff M, Wilson JM | title = Human beta-defensin 2 is a salt-sensitive peptide antibiotic expressed in human lung | journal = The Journal of Clinical Investigation | volume = 102 | issue = 5 | pages = 874–80 | date = September 1998 | pmid = 9727055 | pmc = 508952 | doi = 10.1172/JCI2410 }}
*{{cite journal | vauthors=Liu L, Wang L, Jia HP |title=Structure and mapping of the human beta-defensin HBD-2 gene and its expression at sites of inflammation. |journal=Gene |volume=222 |issue= 2 |pages= 237–44 |year= 1999 |pmid= 9831658 |doi=10.1016/S0378-1119(98)00480-6 |display-authors=etal}}
* {{cite journal | vauthors = Liu L, Wang L, Jia HP, Zhao C, Heng HH, Schutte BC, McCray PB, Ganz T | title = Structure and mapping of the human beta-defensin HBD-2 gene and its expression at sites of inflammation | journal = Gene | volume = 222 | issue = 2 | pages = 237–44 | date = November 1998 | pmid = 9831658 | doi = 10.1016/S0378-1119(98)00480-6 }}
*{{cite journal | vauthors=Mathews M, Jia HP, Guthmiller JM |title=Production of beta-defensin antimicrobial peptides by the oral mucosa and salivary glands. |journal=Infect. Immun. |volume=67 |issue= 6 |pages= 2740–5 |year= 1999 |pmid= 10338476 |doi= |pmc=96577|display-authors=etal}}
* {{cite journal | vauthors = Mathews M, Jia HP, Guthmiller JM, Losh G, Graham S, Johnson GK, Tack BF, McCray PB | title = Production of beta-defensin antimicrobial peptides by the oral mucosa and salivary glands | journal = Infection and Immunity | volume = 67 | issue = 6 | pages = 2740–5 | date = June 1999 | pmid = 10338476 | pmc = 96577 | doi = }}
*{{cite journal | vauthors=Jia HP, Mills JN, Barahmand-Pour F |title=Molecular cloning and characterization of rat genes encoding homologues of human beta-defensins. |journal=Infect. Immun. |volume=67 |issue= 9 |pages= 4827–33 |year= 1999 |pmid= 10456937 |doi= |pmc=96815|display-authors=etal}}
* {{cite journal | vauthors = Jia HP, Mills JN, Barahmand-Pour F, Nishimura D, Mallampali RK, Wang G, Wiles K, Tack BF, Bevins CL, McCray PB | title = Molecular cloning and characterization of rat genes encoding homologues of human beta-defensins | journal = Infection and Immunity | volume = 67 | issue = 9 | pages = 4827–33 | date = September 1999 | pmid = 10456937 | pmc = 96815 | doi = }}
*{{cite journal | vauthors=Yang D, Chertov O, Bykovskaia SN |title=Beta-defensins: linking innate and adaptive immunity through dendritic and T cell CCR6. |journal=Science |volume=286 |issue= 5439 |pages= 525–8 |year= 1999 |pmid= 10521347 |doi=10.1126/science.286.5439.525 |display-authors=etal}}
* {{cite journal | vauthors = Yang D, Chertov O, Bykovskaia SN, Chen Q, Buffo MJ, Shogan J, Anderson M, Schröder JM, Wang JM, Howard OM, Oppenheim JJ | title = Beta-defensins: linking innate and adaptive immunity through dendritic and T cell CCR6 | journal = Science | volume = 286 | issue = 5439 | pages = 525–8 | date = October 1999 | pmid = 10521347 | doi = 10.1126/science.286.5439.525 }}
*{{cite journal | vauthors=Diamond G, Kaiser V, Rhodes J |title=Transcriptional regulation of beta-defensin gene expression in tracheal epithelial cells. |journal=Infect. Immun. |volume=68 |issue= 1 |pages= 113–9 |year= 2000 |pmid= 10603376 |doi= 10.1128/iai.68.1.113-119.2000|pmc=97109|display-authors=etal}}
* {{cite journal | vauthors = Diamond G, Kaiser V, Rhodes J, Russell JP, Bevins CL | title = Transcriptional regulation of beta-defensin gene expression in tracheal epithelial cells | journal = Infection and Immunity | volume = 68 | issue = 1 | pages = 113–9 | date = January 2000 | pmid = 10603376 | pmc = 97109 | doi = 10.1128/iai.68.1.113-119.2000 }}
*{{cite journal | vauthors=Harder J, Meyer-Hoffert U, Teran LM |title=Mucoid Pseudomonas aeruginosa, TNF-alpha, and IL-1beta, but not IL-6, induce human beta-defensin-2 in respiratory epithelia. |journal=Am. J. Respir. Cell Mol. Biol. |volume=22 |issue= 6 |pages= 714–21 |year= 2000 |pmid= 10837369 |doi= 10.1165/ajrcmb.22.6.4023|display-authors=etal}}
* {{cite journal | vauthors = Harder J, Meyer-Hoffert U, Teran LM, Schwichtenberg L, Bartels J, Maune S, Schröder JM | title = Mucoid Pseudomonas aeruginosa, TNF-alpha, and IL-1beta, but not IL-6, induce human beta-defensin-2 in respiratory epithelia | journal = American Journal of Respiratory Cell and Molecular Biology | volume = 22 | issue = 6 | pages = 714–21 | date = June 2000 | pmid = 10837369 | doi = 10.1165/ajrcmb.22.6.4023 }}
*{{cite journal | vauthors=Hoover DM, Rajashankar KR, Blumenthal R |title=The structure of human beta-defensin-2 shows evidence of higher order oligomerization. |journal=J. Biol. Chem. |volume=275 |issue= 42 |pages= 32911–8 |year= 2000 |pmid= 10906336 |doi= 10.1074/jbc.M006098200 |display-authors=etal}}
* {{cite journal | vauthors = Hoover DM, Rajashankar KR, Blumenthal R, Puri A, Oppenheim JJ, Chertov O, Lubkowski J | title = The structure of human beta-defensin-2 shows evidence of higher order oligomerization | journal = The Journal of Biological Chemistry | volume = 275 | issue = 42 | pages = 32911–8 | date = October 2000 | pmid = 10906336 | doi = 10.1074/jbc.M006098200 }}
*{{cite journal | vauthors=Meyer JE, Harder J, Görögh T |title=[hBD-2 gene expression in nasal mucosa] |journal=Laryngorhinootologie |volume=79 |issue= 7 |pages= 400–3 |year= 2000 |pmid= 11005092 |doi= 10.1055/s-2000-4626|display-authors=etal}}
* {{cite journal | vauthors = Meyer JE, Harder J, Görögh T, Schröder JM, Maune S | title = [hBD-2 gene expression in nasal mucosa] | journal = Laryngo- Rhino- Otologie | volume = 79 | issue = 7 | pages = 400–3 | date = July 2000 | pmid = 11005092 | doi = 10.1055/s-2000-4626 }}
*{{cite journal | vauthors=Ali RS, Falconer A, Ikram M |title=Expression of the peptide antibiotics human beta defensin-1 and human beta defensin-2 in normal human skin. |journal=J. Invest. Dermatol. |volume=117 |issue= 1 |pages= 106–11 |year= 2001 |pmid= 11442756 |doi= 10.1046/j.0022-202x.2001.01401.x |display-authors=etal}}
* {{cite journal | vauthors = Ali RS, Falconer A, Ikram M, Bissett CE, Cerio R, Quinn AG | title = Expression of the peptide antibiotics human beta defensin-1 and human beta defensin-2 in normal human skin | journal = The Journal of Investigative Dermatology | volume = 117 | issue = 1 | pages = 106–11 | date = July 2001 | pmid = 11442756 | doi = 10.1046/j.0022-202x.2001.01401.x }}
*{{cite journal | vauthors=Carothers DG, Graham SM, Jia HP |title=Production of beta-defensin antimicrobial peptides by maxillary sinus mucosa. |journal=American journal of rhinology |volume=15 |issue= 3 |pages= 175–9 |year= 2001 |pmid= 11453504 |doi=10.2500/105065801779954238 |display-authors=etal}}
* {{cite journal | vauthors = Carothers DG, Graham SM, Jia HP, Ackermann MR, Tack BF, McCray PB | title = Production of beta-defensin antimicrobial peptides by maxillary sinus mucosa | journal = American Journal of Rhinology | volume = 15 | issue = 3 | pages = 175–9 | year = 2001 | pmid = 11453504 | doi = 10.2500/105065801779954238 }}
*{{cite journal | vauthors=Biragyn A, Surenhu M, Yang D |title=Mediators of innate immunity that target immature, but not mature, dendritic cells induce antitumor immunity when genetically fused with nonimmunogenic tumor antigens. |journal=J. Immunol. |volume=167 |issue= 11 |pages= 6644–53 |year= 2002 |pmid= 11714836 |doi= 10.4049/jimmunol.167.11.6644|display-authors=etal}}
* {{cite journal | vauthors = Biragyn A, Surenhu M, Yang D, Ruffini PA, Haines BA, Klyushnenkova E, Oppenheim JJ, Kwak LW | title = Mediators of innate immunity that target immature, but not mature, dendritic cells induce antitumor immunity when genetically fused with nonimmunogenic tumor antigens | journal = Journal of Immunology | volume = 167 | issue = 11 | pages = 6644–53 | date = December 2001 | pmid = 11714836 | doi = 10.4049/jimmunol.167.11.6644 }}
*{{cite journal | vauthors=Bauer F, Schweimer K, Klüver E |title=Structure determination of human and murine beta-defensins reveals structural conservation in the absence of significant sequence similarity. |journal=Protein Sci. |volume=10 |issue= 12 |pages= 2470–9 |year= 2002 |pmid= 11714914 |doi= 10.1110/ps.24401 |pmc=2374044|display-authors=etal}}
* {{cite journal | vauthors = Bauer F, Schweimer K, Klüver E, Conejo-Garcia JR, Forssmann WG, Rösch P, Adermann K, Sticht H | title = Structure determination of human and murine beta-defensins reveals structural conservation in the absence of significant sequence similarity | journal = Protein Science | volume = 10 | issue = 12 | pages = 2470–9 | date = December 2001 | pmid = 11714914 | pmc = 2374044 | doi = 10.1110/ps.24401 }}
*{{cite journal | vauthors=Takahashi A, Wada A, Ogushi K |title=Production of beta-defensin-2 by human colonic epithelial cells induced by Salmonella enteritidis flagella filament structural protein. |journal=FEBS Lett. |volume=508 |issue= 3 |pages= 484–8 |year= 2001 |pmid= 11728477 |doi=10.1016/S0014-5793(01)03088-5 |display-authors=etal}}
* {{cite journal | vauthors = Takahashi A, Wada A, Ogushi K, Maeda K, Kawahara T, Mawatari K, Kurazono H, Moss J, Hirayama T, Nakaya Y | title = Production of beta-defensin-2 by human colonic epithelial cells induced by Salmonella enteritidis flagella filament structural protein | journal = FEBS Letters | volume = 508 | issue = 3 | pages = 484–8 | date = November 2001 | pmid = 11728477 | doi = 10.1016/S0014-5793(01)03088-5 }}
*{{cite journal | vauthors=Schibli DJ, Hunter HN, Aseyev V |title=The solution structures of the human beta-defensins lead to a better understanding of the potent bactericidal activity of HBD3 against Staphylococcus aureus. |journal=J. Biol. Chem. |volume=277 |issue= 10 |pages= 8279–89 |year= 2002 |pmid= 11741980 |doi= 10.1074/jbc.M108830200 |display-authors=etal}}
* {{cite journal | vauthors = Schibli DJ, Hunter HN, Aseyev V, Starner TD, Wiencek JM, McCray PB, Tack BF, Vogel HJ | title = The solution structures of the human beta-defensins lead to a better understanding of the potent bactericidal activity of HBD3 against Staphylococcus aureus | journal = The Journal of Biological Chemistry | volume = 277 | issue = 10 | pages = 8279–89 | date = March 2002 | pmid = 11741980 | doi = 10.1074/jbc.M108830200 }}
{{refend}}
{{refend}}


{{PDB Gallery|geneid=1673}}
{{PDB Gallery|geneid=1673}}


{{protein-stub}}


{{protein-stub}}
[[Category:Defensins]]

Latest revision as of 08:51, 10 January 2019

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Beta-defensin 2 (BD-2) also known as skin-antimicrobial peptide 1 (SAP1) is a peptide that in humans is encoded by the DEFB4 (defensin, beta 4) gene.[1]

Human beta-defensin-2 (hBD-2) is a cysteine-rich cationic low molecular weight antimicrobial peptide recently discovered in lesional skin.

Structure

hBD-2 is a protein whose primary structure is made by 64 aminoacids. At concentrations ≤2.4 mM, hBD-2 is monomeric.[2] The structure is amphiphilic with a nonuniform surface distribution of positive charge and contains several key structural elements, including a triple-stranded, antiparallel beta sheet with strands 2 and 3 in a beta hairpin conformation. The determination of other structural elements depends on the technique used. When X-ray crystallography is used an alpha helix can be observed at the N-terminal end of the protein (PDB codes: 1fd3​,1fd4​, and 6cs9​). When using NMR this alpha-helix does not appear (PDB code: 1e4q​), however this structure was determined using a truncated version of hBD-2 which was missing the initial 4 amino acids, and may be the reason for the discrepancy.

Function

Defensins form a family of microbicidal and cytotoxic peptides made by neutrophils. Members of the defensin family are highly similar in protein sequence. Beta-defensin 2 is an antibiotic peptide which is locally regulated by inflammation.[3]

Human beta-defensin 2 is produced by a number of epithelial cells and exhibits potent antimicrobial activity against Gram-negative bacteria and Candida, but not Gram-positive S. aureus. It has been speculated that beta-defensin 2 may contribute to the infrequency of Gram-negative infections on skin and lung tissue.[4]

hBD-2 represents the first human defensin that is produced following stimulation of epithelial cells by contact with microorganisms such as P. aeruginosa or cytokines such as TNF-alpha and IL-1 beta. The HBD-2 gene and protein are locally expressed in keratinocytes associated with inflammatory skin lesions. It is intriguing to speculate that HBD-2 is a dynamic component of the local epithelial defense system of the skin and respiratory tract having a role to protect surfaces from infection, and providing a possible reason why skin and lung infections with Gram-negative bacteria are rather rare.[4]

Although this protein doesn’t have any antibacterial activity against Gram-positive bacteria, there is a study showing that there is a synergy between hBD-2 and other proteins.[5] One example of this synergistic effect is with epiP, a protein segregated by some strains of S. epidermidis. hBD2, holding hands with epiP, is capable of killing S. aureus, a Gram-positive bacteria responsible of human diseases.

References

  1. Harder J, Bartels J, Christophers E, Schröder JM (June 1997). "A peptide antibiotic from human skin". Nature. 387 (6636): 861. doi:10.1038/43088. PMID 9202117.
  2. Sawai MV, Jia HP, Liu L, Aseyev V, Wiencek JM, McCray PB, Ganz T, Kearney WR, Tack BF (April 2001). "The NMR structure of human beta-defensin-2 reveals a novel alpha-helical segment". Biochemistry. 40 (13): 3810–6. doi:10.1021/bi002519d. PMID 11300761.
  3. "Entrez Gene: DEFB4 defensin, beta 4".
  4. 4.0 4.1 Schröder JM, Harder J (June 1999). "Human beta-defensin-2". The International Journal of Biochemistry & Cell Biology. 31 (6): 645–51. doi:10.1016/S1357-2725(99)00013-8. PMID 10404637.
  5. Iwase T, Uehara Y, Shinji H, Tajima A, Seo H, Takada K, Agata T, Mizunoe Y (May 2010). "Staphylococcus epidermidis Esp inhibits Staphylococcus aureus biofilm formation and nasal colonization". Nature. 465 (7296): 346–9. doi:10.1038/nature09074. PMID 20485435.

External links

Further reading