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<Structure load='4ea0' size='350' frame='true' align='right' caption='Dehydrosqualene synthase complexed with diphosphate and quinuclidine BPH-651' scene='Insert optional scene name here' />
<Structure load='4ea0' size='350' frame='true' align='right' caption='Dehydrosqualene synthase complexed with diphosphate and quinuclidine BPH-651' scene='Insert optional scene name here' />
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== Presentation of dehydrosqualene synthase ==
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== General ==
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The [https://www.ncbi.nlm.nih.gov/protein/Q2FV59.1/ C30 carotene synthase] (also known as 4,4'-diapophytoene (DAP) synthase; dehydrosqualene synthase; CrtM), encoded by ''crtM'' gene, is a bacterial carotenoid synthase which is involved in the first step of the pathway that synthesizes staphyloxanthin from farnesyl diphosphate.
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The [https://www.ncbi.nlm.nih.gov/protein/Q2FV59.1/ C30 carotene synthase] (also known as 4,4'-diapophytoene (DAP) synthase; dehydrosqualene synthase; CrtM), encoded by ''crtM'' gene, is a bacterial carotenoid synthase which is involved in the first step of the pathway that synthesizes staphyloxanthin from farnesyl diphosphate. Staphyloxanthin biosynthesis is a part of carotenoid biosynthesis, which is again a branch of the general isoprenoid pathway.
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This pathway is a subpathway in staphyloxanthin biosynthesis, which is itself part of carotenoid biosynthesis. Carotenoid pathways are branches of the general isoprenoid pathway.
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Staphyloxanthin is a carotenoid, which is responsible for the signature golden color of ''Staphylococcus aureus'' and also plays the role of virulence factor to human. It has an antioxidant activity that helps the microbe to survive under hight concentration of reactive oxygen species, caused by the host immune system. Having a better comprehension of the synthesis of this carotenoid will help to find a cure to ''S. aureus'' related diseases.
Staphyloxanthin is a carotenoid, which is responsible for the signature golden color of ''Staphylococcus aureus'' and also plays the role of virulence factor to human. It has an antioxidant activity that helps the microbe to survive under hight concentration of reactive oxygen species, caused by the host immune system. Having a better comprehension of the synthesis of this carotenoid will help to find a cure to ''S. aureus'' related diseases.
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== Function(Biological reaction) ==
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== Biological function ==
CrtM catalyses the first step of the synthesis of staphyloxanthin (with a 2-step mechanism)<ref>DOI: 10.1128/IAI.00204-06</ref><ref name="IoSV">DOI: 10.1021/jm9001764</ref>. The enzyme can bind with two substrates.
CrtM catalyses the first step of the synthesis of staphyloxanthin (with a 2-step mechanism)<ref>DOI: 10.1128/IAI.00204-06</ref><ref name="IoSV">DOI: 10.1021/jm9001764</ref>. The enzyme can bind with two substrates.
; Catalysed reaction (head-to-head condensation)
; Catalysed reaction (head-to-head condensation)
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Transferase Activity : Transferring alkyl or aryl groups, other than methyl groups
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Transferase Activity : Transferring alkyl or aryl groups, other than methyl groups {{Citation needed|reason=Reliable source needed for the whole sentence|date=January 2019}}
Metal Ion Binding : requires Mn<sup>2+</sup> as cofactor (2 ions per subunit).
Metal Ion Binding : requires Mn<sup>2+</sup> as cofactor (2 ions per subunit).
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CrtM is an isoprenoid synthase. This enzyme consists of 2 sequence-identical polypeptide chains of 287 amino acids<ref>DOI: 10.1128/genomeA.00374-16</ref>. It is all helical and has a large central cavity<ref name="ACBI" />. There are two Asp-rich region with the motive DXXXD, where the aspartic acid pairs D48, D52 and D172, D176 are essential for catalyzing the reaction<ref name="Moaa">DOI: 10.1073/pnas.1010907107</ref>. <scene name='80/802670/Active_site/1'>See JSmol image</scene>
CrtM is an isoprenoid synthase. This enzyme consists of 2 sequence-identical polypeptide chains of 287 amino acids<ref>DOI: 10.1128/genomeA.00374-16</ref>. It is all helical and has a large central cavity<ref name="ACBI" />. There are two Asp-rich region with the motive DXXXD, where the aspartic acid pairs D48, D52 and D172, D176 are essential for catalyzing the reaction<ref name="Moaa">DOI: 10.1073/pnas.1010907107</ref>. <scene name='80/802670/Active_site/1'>See JSmol image</scene>
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; Ligands
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; Ligands{{Citation needed|reason=Reliable source needed for the whole sentence|date=January 2019}}
: 6 Magnesium ions
: 6 Magnesium ions
: 2 PO<sub>4</sub><sup>2-</sup>
: 2 PO<sub>4</sub><sup>2-</sup>
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== Human diseases ==
== Human diseases ==
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The Staphyloxanthin catalyzed by CrtM is a virulence factor linked with infections caused by methicillin-resistant ''Staphylococcus aureus'' (MRSA), which is becoming a serious threat<ref>DOI:10.1001/jama.298.15.1763</ref>. Cells with mutated CrtM are less resistant against oxidative stress, shows lower survival rate and are less pathogenic in mouses<ref>DOI:10.1084/jem.20050846</ref>. Due to its structural similarity as well as shared inhibitor with human squalene synthase (SQS)<ref name="ACBI"/><ref>DOI: 10.1021/jm300208p</ref>, it is seen as a potential target for virulence factor neutralization therapy, where the idea is to inhibit the pathogen's synthetic pathway. Drugs intended to lower the cholesterol level might have a positive effect on fighting the infection<ref name="IoSV"/>.
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The Staphyloxanthin catalyzed by CrtM is a virulence factor linked with infections caused by methicillin-resistant ''Staphylococcus aureus'' (MRSA), which is becoming a serious threat<ref>DOI:10.1001/jama.298.15.1763</ref>. Cells with mutated CrtM are less resistant against oxidative stress, shows lower survival rate and are less pathogenic in mouse<ref>DOI:10.1084/jem.20050846</ref>. Due to its structural similarity as well as shared inhibitor with human squalene synthase (SQS)<ref name="ACBI"/><ref>DOI: 10.1021/jm300208p</ref>, it is seen as a potential target for virulence factor neutralization therapy, where the idea is to inhibit the pathogen's synthetic pathway. Drugs intended to lower the cholesterol level might have a positive effect on fighting the infection<ref name="IoSV"/>.
Cationic inhibitors are here of interest as anti-infectives because they can substitute themselves to Mg<sup>2+</sup> and inactivate the enzyme.
Cationic inhibitors are here of interest as anti-infectives because they can substitute themselves to Mg<sup>2+</sup> and inactivate the enzyme.

Revision as of 18:47, 11 January 2019

This Sandbox is Reserved from 06/12/2018, through 30/06/2019 for use in the course "Structural Biology" taught by Bruno Kieffer at the University of Strasbourg, ESBS. This reservation includes Sandbox Reserved 1480 through Sandbox Reserved 1543.
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Dehydrosqualene synthase complexed with diphosphate and quinuclidine BPH-651

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Contents

General

The C30 carotene synthase (also known as 4,4'-diapophytoene (DAP) synthase; dehydrosqualene synthase; CrtM), encoded by crtM gene, is a bacterial carotenoid synthase which is involved in the first step of the pathway that synthesizes staphyloxanthin from farnesyl diphosphate. Staphyloxanthin biosynthesis is a part of carotenoid biosynthesis, which is again a branch of the general isoprenoid pathway.

Staphyloxanthin is a carotenoid, which is responsible for the signature golden color of Staphylococcus aureus and also plays the role of virulence factor to human. It has an antioxidant activity that helps the microbe to survive under hight concentration of reactive oxygen species, caused by the host immune system. Having a better comprehension of the synthesis of this carotenoid will help to find a cure to S. aureus related diseases.


Biological function

CrtM catalyses the first step of the synthesis of staphyloxanthin (with a 2-step mechanism)[1][2]. The enzyme can bind with two substrates.

Catalysed reaction (head-to-head condensation)
2 (2E,6E)-farnesyl diphosphate (FPP) ↔15-cis-4,4'-diapophytoene + 2 diphosphate

The gene is located in the staphyloxanthin biosynthesis operon (crtOPQMN), which encodes enzymes to catalyze the synthesis[3]. The product, C(30) carotenoid 4,4'-diapophytoene (dehydrosqualene), is colorless.


Transferase Activity : Transferring alkyl or aryl groups, other than methyl groups Template:Citation needed

Metal Ion Binding : requires Mn2+ as cofactor (2 ions per subunit).

Structure

CrtM is an isoprenoid synthase. This enzyme consists of 2 sequence-identical polypeptide chains of 287 amino acids[4]. It is all helical and has a large central cavity[5]. There are two Asp-rich region with the motive DXXXD, where the aspartic acid pairs D48, D52 and D172, D176 are essential for catalyzing the reaction[6].

LigandsTemplate:Citation needed
6 Magnesium ions
2 PO42-
1 L(+)-tartaric acid
2 (3r)-3-biphenyl-4-yl-1-azabicyclo[2.2.2]octan-3-ol

The space group of FsPP·CrtM is P3121, with two molecules per asymmetric unit. Three phosphonosulfonates, which mimic the FPP substract have been identified to have binding/inhibiting activity on CrtM, each with different binding pattern. For one of the phosphonosulfonate, Mg2+ isn't essential for the inhibitor to bind [5].

Human diseases

The Staphyloxanthin catalyzed by CrtM is a virulence factor linked with infections caused by methicillin-resistant Staphylococcus aureus (MRSA), which is becoming a serious threat[7]. Cells with mutated CrtM are less resistant against oxidative stress, shows lower survival rate and are less pathogenic in mouse[8]. Due to its structural similarity as well as shared inhibitor with human squalene synthase (SQS)[5][9], it is seen as a potential target for virulence factor neutralization therapy, where the idea is to inhibit the pathogen's synthetic pathway. Drugs intended to lower the cholesterol level might have a positive effect on fighting the infection[2]. Cationic inhibitors are here of interest as anti-infectives because they can substitute themselves to Mg2+ and inactivate the enzyme.

Links

RCSB PDB
UniProt

References

  1. ↑ Clauditz A, Resch A, Wieland KP, Peschel A, Gotz F. Staphyloxanthin plays a role in the fitness of Staphylococcus aureus and its ability to cope with oxidative stress. Infect Immun. 2006 Aug;74(8):4950-3. doi: 10.1128/IAI.00204-06. PMID:16861688 doi:http://dx.doi.org/10.1128/IAI.00204-06
  2. ↑ 2.0 2.1 Song Y, Liu CI, Lin FY, No JH, Hensler M, Liu YL, Jeng WY, Low J, Liu GY, Nizet V, Wang AH, Oldfield E. Inhibition of staphyloxanthin virulence factor biosynthesis in Staphylococcus aureus: in vitro, in vivo, and crystallographic results. J Med Chem. 2009 Jul 9;52(13):3869-80. PMID:19456099 doi:10.1021/jm9001764
  3. ↑ Pelz A, Wieland KP, Putzbach K, Hentschel P, Albert K, Gotz F. Structure and biosynthesis of staphyloxanthin from Staphylococcus aureus. J Biol Chem. 2005 Sep 16;280(37):32493-8. doi: 10.1074/jbc.M505070200. Epub 2005 , Jul 14. PMID:16020541 doi:http://dx.doi.org/10.1074/jbc.M505070200
  4. ↑ Aswani V, Mau B, Shukla SK. Complete Genome Sequence of Staphylococcus aureus MCRF184, a Necrotizing Fasciitis-Causing Methicillin-Sensitive Sequence Type 45 Staphylococcus Strain. Genome Announc. 2016 May 12;4(3). pii: 4/3/e00374-16. doi:, 10.1128/genomeA.00374-16. PMID:27174283 doi:http://dx.doi.org/10.1128/genomeA.00374-16
  5. ↑ 5.0 5.1 5.2 Liu CI, Liu GY, Song Y, Yin F, Hensler ME, Jeng WY, Nizet V, Wang AH, Oldfield E. A cholesterol biosynthesis inhibitor blocks Staphylococcus aureus virulence. Science. 2008 Mar 7;319(5868):1391-4. Epub 2008 Feb 14. PMID:18276850
  6. ↑ Lin FY, Liu CI, Liu YL, Zhang Y, Wang K, Jeng WY, Ko TP, Cao R, Wang AH, Oldfield E. Mechanism of action and inhibition of dehydrosqualene synthase. Proc Natl Acad Sci U S A. 2010 Nov 23. PMID:21098670 doi:10.1073/pnas.1010907107
  7. ↑ Klevens RM, Morrison MA, Nadle J, Petit S, Gershman K, Ray S, Harrison LH, Lynfield R, Dumyati G, Townes JM, Craig AS, Zell ER, Fosheim GE, McDougal LK, Carey RB, Fridkin SK. Invasive methicillin-resistant Staphylococcus aureus infections in the United States. JAMA. 2007 Oct 17;298(15):1763-71. doi: 10.1001/jama.298.15.1763. PMID:17940231 doi:http://dx.doi.org/10.1001/jama.298.15.1763
  8. ↑ Liu GY, Essex A, Buchanan JT, Datta V, Hoffman HM, Bastian JF, Fierer J, Nizet V. Staphylococcus aureus golden pigment impairs neutrophil killing and promotes virulence through its antioxidant activity. J Exp Med. 2005 Jul 18;202(2):209-15. doi: 10.1084/jem.20050846. Epub 2005 Jul, 11. PMID:16009720 doi:http://dx.doi.org/10.1084/jem.20050846
  9. ↑ Lin FY, Liu YL, Li K, Cao R, Zhu W, Axelson J, Pang R, Oldfield E. Head-to-Head Prenyl Tranferases: Anti-Infective Drug Targets. J Med Chem. 2012 May 10;55(9):4367-72. Epub 2012 May 1. PMID:22486710 doi:10.1021/jm300208p
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