Proteopedia

Complement Regulator-Acquiring Surface Protein: Difference between revisions

← Older editNewer edit →
No edit summary
No edit summary
Line 5: Line 5:
[http://en.wikipedia.org/wiki/Lyme_disease Lyme Disease] is caused by the [http://en.wikipedia.org/wiki/Spirochaete spirochete] [http://en.wikipedia.org/wiki/Borrelia_burgdorferi ''Borrelia burgdorferi''], and is transferred into vertebrate hosts by zoonotic vectors such as [http://en.wikipedia.org/wiki/Ixodes ''Ixodes''] ticks <ref name="Bykowski">PMID: 17562769</ref>. Lyme disease can result in multisystemic disorders, including cardiovascular and neurological problems. There are thousands of cases of Lyme disease reported each year, making it a prevalent disease in North America and Eurasia <ref name="Cordes">PMID: 15711564</ref>. In order for ''B. burgdorferi'' to survive in its host, it evades the host's immune system through the use of complement regulator-acquiring surface proteins. One such protein responsible for a successful initial infection is ''Borrelia burgdorferi'' complement regulator-acquiring surface protein 1, or BbCRASP-1 <ref name="Bykowski">PMID: 17562769</ref>. Because BbCRASP-1 binds host complement regulators to the spirochete's outer surface, ''B. burgdorferi'' remains undetected within the host <ref name="Bykowski">PMID: 17562769</ref>. BbCRASP-1 specifically binds to complement Factor H (FH) and Factor H-like proteins (FHL-1), which are responsible for the host's immune response and detection of pathogens <ref name="Kraiczy">PMID: 14607842</ref>. Recently, it was found that BbCRASP-1 binds to several other proteins in the extra cellular matrix of a human cell, making it highly flexible and adaptive.
[http://en.wikipedia.org/wiki/Lyme_disease Lyme Disease] is caused by the [http://en.wikipedia.org/wiki/Spirochaete spirochete] [http://en.wikipedia.org/wiki/Borrelia_burgdorferi ''Borrelia burgdorferi''], and is transferred into vertebrate hosts by zoonotic vectors such as [http://en.wikipedia.org/wiki/Ixodes ''Ixodes''] ticks <ref name="Bykowski">PMID: 17562769</ref>. Lyme disease can result in multisystemic disorders, including cardiovascular and neurological problems. There are thousands of cases of Lyme disease reported each year, making it a prevalent disease in North America and Eurasia <ref name="Cordes">PMID: 15711564</ref>. In order for ''B. burgdorferi'' to survive in its host, it evades the host's immune system through the use of complement regulator-acquiring surface proteins. One such protein responsible for a successful initial infection is ''Borrelia burgdorferi'' complement regulator-acquiring surface protein 1, or BbCRASP-1 <ref name="Bykowski">PMID: 17562769</ref>. Because BbCRASP-1 binds host complement regulators to the spirochete's outer surface, ''B. burgdorferi'' remains undetected within the host <ref name="Bykowski">PMID: 17562769</ref>. BbCRASP-1 specifically binds to complement Factor H (FH) and Factor H-like proteins (FHL-1), which are responsible for the host's immune response and detection of pathogens <ref name="Kraiczy">PMID: 14607842</ref>. Recently, it was found that BbCRASP-1 binds to several other proteins in the extra cellular matrix of a human cell, making it highly flexible and adaptive.


== '''Function''' ==
<applet load='BBCRASP-12' size='250' frame='true' align='right' caption='BbCRASP-1' scene='Insert optional scene name here' />


BbCRASP-1 can be found on the outer layer of the Lyme disease spirochete and is essential for the infiltration of the spirochete into the host <ref name="Bykowski">PMID: 17562769</ref>. BbCRASP-1 provides resistance for the spirochete against the host's complementary immune system as well as spreading of the spirochete within the host. 
== '''Structure''' ==


=== '''Host Immune Response Evasion''' ===
In nature, BbCRASP-1 exists as a homodimer bound to the spirochete's surface <ref name="Cordes">PMID: 15711564</ref>. BbCRASP-1 needs to be dimerized in order to bind FH/FHL-1 proteins. If its dimeric state is threatened, BbCRASP-1 would not be able to function.


BbCRASP-1 has an affinity for [http://www.uniprot.org/uniprot/CFAH_HUMAN Factor H] (a regulatory protein secreted by the [http://en.wikipedia.org/wiki/Complement_system complement immune system]) and Factor H-like proteins. Therefore, Factor H binds to BbCRASP-1, which is bound to the outer surface of the spirochete. Because there are multiple BbCRASP-1 proteins on the spirochete,  the spirochete is coated  with Factor H and effectively able to infiltrate the host and go undetected in the host's plasma<ref name="Bykowski">PMID: 17562769</ref>.
=== '''Importance of the C-terminus''' ===


=== '''Relation to the Extra Cellular Matrix''' ===
The C-terminus of BbCRASP-1 is a region crucial for its stability as a dimer. Previously,sequences of high conservation in the C-terminal regions of the protein’s monomers, <scene name='SB2013_L01gr6/C-terminus/1'>residues 241 to 250</scene> , were of interest as a potential binding site <ref name="Cordes">PMID: 15711564</ref>. Prior studies showed that deletion of these sites caused a complete inability of BbCRASP-1 to bind FH and FHL-1 regulators <ref name="Kraiczy">PMID: 14607842</ref>. The role of the C-terminus was determined by mutating <scene name='SB2013_L01gr6/Leucine_246/2'>leucine 246</scene> in this region of the dimer to aspartate <ref name="Cordes">PMID: 15711564</ref>. Both the C-terminally truncated and mutated BbCRASP-1 proteins lost their ability to dimerize, inhibiting them from binding to their host’s regulatory factors. It was then concluded that the C-terminus is a structurally sensitive region rather than a direct binding site <ref name="Cordes">PMID: 15711564</ref>. The C-terminus one monomer lies against the <scene name='SB2013_L01gr6/N-terminal_helix_ribbon/1'>N-terminal half of the E helix</scene> of the other and holds the <scene name='SB2013_L01gr6/Monomers_and_cterminus/1'>two monomers</scene> in place <ref name="Cordes">PMID: 15711564</ref>.


Recently it was found that BbCRASP-1 not only binds to FH and FHL-1 proteins, but it also binds to several other human ligands such as [http://www.uniprot.org/uniprot/BMP2_HUMAN BMP-2] and Extra cellular matrix ligands Collagen I, Collagen III, Collagen IV, fibronectin, laminin, and plasminogen <ref name"Hallstrom">PMID: 20565259</ref>. As a result of this new  finding, BbCRASP-1 is said to not only advocate the bypassing of the complementary immune system, but facilitate the dissemination of ''B. burgdorferi'' within the host's tissues <ref name"Hallström">PMID: 20565259</ref>. Binding to the ECM of a host is common strategy used by pathogens to acquire contact within the host  <ref name"Burgmann">PMID: 19118218</ref><ref name"Hallström">PMID: 16785539</ref>.
=== '''Other Potential Binding Sites''' ===


Additional studies were done to investigate the FH and FHL-1 binding sites on the protein. As with previous research, areas of high conservation were investigated due to their relationship with upholding the structure and function of the protein <ref name="CordesF">PMID: 16530476</ref>. Highly conserved areas of amino acid sequences among Borrelia CRASP-1 proteins encoded by the same gene were examined. The greatest homologous region was clustered on the <scene name='SB2013_L01gr6/Pocket_region_with_blue_fill/1'>center of the cleft region</scene> of the protein.  A binding site in this region would be probable because this area allows more contact with the regulator proteins and would aid in further evasion of the immune system by shielding the binding domain from potential detection <ref name="CordesF">PMID: 16530476</ref>.


<applet load='BBCRASP-12' size='250' frame='true' align='right' caption='BbCRASP-1' scene='Insert optional scene name here' />
== '''Function''' ==


== '''Structure''' ==
BbCRASP-1 can be found on the outer layer of the Lyme disease spirochete and is essential for the infiltration of the spirochete into the host <ref name="Bykowski">PMID: 17562769</ref>. BbCRASP-1 provides resistance for the spirochete against the host's complementary immune system as well as spreading of the spirochete within the host. 


In nature, BbCRASP-1 exists as a homodimer bound to the spirochete's surface <ref name="Cordes">PMID: 15711564</ref>. BbCRASP-1 needs to be dimerized in order to bind FH/FHL-1 proteins. If its dimeric state is threatened, BbCRASP-1 would not be able to function.
=== '''Host Immune Response Evasion''' ===


=== '''Importance of the C-terminus''' ===
BbCRASP-1 has an affinity for [http://www.uniprot.org/uniprot/CFAH_HUMAN Factor H] (a regulatory protein secreted by the [http://en.wikipedia.org/wiki/Complement_system complement immune system]) and Factor H-like proteins. Therefore, Factor H binds to BbCRASP-1, which is bound to the outer surface of the spirochete. Because there are multiple BbCRASP-1 proteins on the spirochete,  the spirochete is coated  with Factor H and effectively able to infiltrate the host and go undetected in the host's plasma<ref name="Bykowski">PMID: 17562769</ref>.


The C-terminus of BbCRASP-1 is a region crucial for its stability as a dimer. Previously,sequences of high conservation in the C-terminal regions of the protein’s monomers, <scene name='SB2013_L01gr6/C-terminus/1'>residues 241 to 250</scene> , were of interest as a potential binding site <ref name="Cordes">PMID: 15711564</ref>. Prior studies showed that deletion of these sites caused a complete inability of BbCRASP-1 to bind FH and FHL-1 regulators <ref name="Kraiczy">PMID: 14607842</ref>. The role of the C-terminus was determined by mutating <scene name='SB2013_L01gr6/Leucine_246/2'>leucine 246</scene> in this region of the dimer to aspartate <ref name="Cordes">PMID: 15711564</ref>. Both the C-terminally truncated and mutated BbCRASP-1 proteins lost their ability to dimerize, inhibiting them from binding to their host’s regulatory factors. It was then concluded that the C-terminus is a structurally sensitive region rather than a direct binding site <ref name="Cordes">PMID: 15711564</ref>. The C-terminus one monomer lies against the <scene name='SB2013_L01gr6/N-terminal_helix_ribbon/1'>N-terminal half of the E helix</scene> of the other and holds the <scene name='SB2013_L01gr6/Monomers_and_cterminus/1'>two monomers</scene> in place <ref name="Cordes">PMID: 15711564</ref>.
=== '''Relation to the Extra Cellular Matrix''' ===


=== '''Other Potential Binding Sites''' ===
Recently it was found that BbCRASP-1 not only binds to FH and FHL-1 proteins, but it also binds to several other human ligands such as [http://www.uniprot.org/uniprot/BMP2_HUMAN BMP-2] and Extra cellular matrix ligands Collagen I, Collagen III, Collagen IV, fibronectin, laminin, and plasminogen <ref name"Hallstrom">PMID: 20565259</ref>. As a result of this new  finding, BbCRASP-1 is said to not only advocate the bypassing of the complementary immune system, but facilitate the dissemination of ''B. burgdorferi'' within the host's tissues <ref name"Hallström">PMID: 20565259</ref>. Binding to the ECM of a host is common strategy used by pathogens to acquire contact within the host  <ref name"Burgmann">PMID: 19118218</ref><ref name"Hallström">PMID: 16785539</ref>.
 
Additional studies were done to investigate the FH and FHL-1 binding sites on the protein. As with previous research, areas of high conservation were investigated due to their relationship with upholding the structure and function of the protein <ref name="CordesF">PMID: 16530476</ref>. Highly conserved areas of amino acid sequences among Borrelia CRASP-1 proteins encoded by the same gene were examined. The greatest homologous region was clustered on the <scene name='SB2013_L01gr6/Pocket_region_with_blue_fill/1'>center of the cleft region</scene> of the protein. A binding site in this region would be probable because this area allows more contact with the regulator proteins and would aid in further evasion of the immune system by shielding the binding domain from potential detection <ref name="CordesF">PMID: 16530476</ref>.


== '''Discussion''' ==
== '''Discussion''' ==

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

Kerry Brathwaite, Dipanshu Walia, Michal Harel, Kwangsun Yoo, Jaime Prilusky, Alexander Berchansky
Retrieved from "https://proteopedia.openfox.io/w/Complement_Regulator-Acquiring_Surface_Protein"