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==Crystal structure of the Antennal Specific Protein-1 from Apis mellifera (AmelASP1) with a serendipitous ligand at pH 5.5==
<StructureSection load='3fe6' size='400' side='right'
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<nowiki>

The protein AmelASP1 has been identified in the antennae from the honeybee A.mellifera. Its primary sequence is a 144 amino acids polypeptide with a molecular weight of 13.180 kDa. AmelASP1 is part of the Pheromone Binding Protein (PBP) family. The 3D representation shown below was obtained at pH 5.5 using the nano-drops technique.

=Biological function=
As many other social insects, honeybees employ a large varsity of pheromones to ensure intraspecific communication in several behavioral contexts.
The social organization of the hive is strongly determined by chemical signals, also known as pheromones, that are actively produced and transmitted by the queen.

==Social relevance==
The diet of workers bees and queen bee is strongly different and determinates diverse behaviours.
Workers bee are fed with royal jelly for only three days after egg-laying whereas the queen bee eats royal jelly during her whole life. She controls the activity of each bees by chemical communication.
Actually, the queen bee is the only one able to produce 9-ODA - the main component of its pheromone which induces sexual or endocrine responses. This substance is sent to the workers bees which detect it through pheromone-binding proteins (PBPs). It is then transformed in 9-HDA and added in the royal jelly. This last substance is eaten by the queen. In turn, queen bee transforms 9-HDA into 9-ODA.
Thus, ASP1 is primordial to the internal pheromon’s transport cycle in the hive. By binding the component of queen bee pheromon, bees blend essential behaviour for the swarm. Indeed, 9-ODA is responsible, among others, of preventing workers bees’ ovarian developpment.
In order to determine this proteine’s structure, a serendipitous ligand has been used at pH 5.5. This low pH fit with the natural medium of this protein in the bee antenna.

<ref>PMID: 18508083</ref>
<ref>PMID: 19481550</ref>
<ref>PMID: 25337796</ref>
<ref>PMID: 14594955</ref>

Updated on {{REVISIONDAY2}}-{{MONTHNAME|{{REVISIONMONTH}}}}-{{REVISIONYEAR}}

== Biological function ==
=== Social relevance ===

=== Location in the antenna and transport of pheromones ===

== Structure ==

[[Image: 3fe6_cartoon.jpg|250px|left|thumb|'''Fig.1''' Ribbon colored representation]]

=== Domains and family ===
The C terminal(scene) domain of this molecule presents a characteristic PBP-GOP domain. While this protein is composed of 144 residues the domain PBP begin at the 25th residue. AmelASP1 binds its ligand at low pH and releases it at neutral pH.

=== Key residues ===
AmelASP1 is composed of <scene name='60/604479/Helixes/1'>7 right-handed alpha helices</scene><ref> http://www.genome.jp/dbget-bin/www_bget?pdb:3FE6</ref>
** <scene name='60/604479/H1/2'>H1</scene>: residues 8–25
** <scene name='60/604479/H2/2'>H2</scene>: residues 27–36
** <scene name='60/604479/H3/2'>H3</scene>: residues 42–56
** <scene name='60/604479/H4/1'>H4</scene>: residues 66–74
** <scene name='60/604479/H5/1'>H5</scene>: residues 75–77 (rarely mentionned in publications because of its tiny size)
** <scene name='60/604479/H6/1'>H6</scene>: residues 78–90
** <scene name='60/604479/H7/1'>H7</scene>: residues 96–112

<scene name='60/604479/H1/2'>H1</scene> has a break in the hydrogen-bonding pattern of its structure, forming tight substitute hydrogen bonds with water molecules. Thus, it results in a <scene name='60/604479/Kink/1'>kink</scene> (at residue Ala 14) induced by a disruption in the helical conformation, due to hydrogen bonds with water molecules.

=== Components implicated in the structure rigidity ===
AmelASP1 presents <scene name='60/604479/Disulfide_bonds/1'> three disulfide bridges</scene> which are greatly enhancing its structure’s rigidity by linking four of the helices together. The six cysteines and their interval spacing are the most striking features shared by proteins belonging to the PBP family.

The <scene name='60/604479/1st_disulfide_bridge/1'>first disulfide bridge</scene> is established between <scene name='60/604479/H1/2'>H1</scene> and <scene name='60/604479/H3/2'>H3</scene> through Cysteins 20 and 51. <scene name='60/604479/2nd_disulfide_bridge/2'>An other disulfide bridge</scene> links <scene name='60/604479/H3/2'>H3</scene> and <scene name='60/604479/H6/1'>H6</scene> through Cys 47 and 98, and the <scene name='60/604479/3rd_disulfide_bridge/1'>third disulfide bridge</scene> connects <scene name='60/604479/H5/1'>H5</scene> and <scene name='60/604479/H6/1'>H6</scene> thanks to Cys 89 and Cys 107.

Furthermore, non covalent bonds also play an important role.
Indeed, at pH 5.5, among the numerous other, two hydrogene bonds are particularly noticeable because of their importance in the formation of the loop stabilizing H4. <scene name='60/604479/Hydrogene_bond_1/2'>One</scene> is established by Asp 66 and Leu 58 whereas <scene name='60/604479/Hydrogene_bond_2/1'>the second</scene> is formed between Asp 60 and Ala 63.

=== Cavity ===
The dynamic structure of the protein is responsible of the ligand’s binding by adjustment of position. The structure looses its flexibility when <scene name='60/604479/Cmj/3'>CMJ</scene> binds. The successful delivery of the effector to the receptor relies on this property. The ligand binding pocket consists in a cavity formed by the helices H2, H4 and H5(scene), arranged in a globular shape which leads to a clear separation of the
ligand from the hydrophilic environment.
The top of the cavity is not closed and can establish contacts with the solvent. The cavity is prone to accept ligand such as 9-ODA because of its specific composition. Indeed, cavity's components are mainly <scene name='60/604479/Hydrophobic_residues/2'>hydrophobic and aromatic</scene>.They consequently interact with the ligand's hydrophobic carbon chain and are localized on the internal face of the helix.Thus, it implies that these residues respect a regular distance pattern in the primary structure of the AmelASP1.

=== pH influence ===

== Ligands ==
=== Artificial ligands ===

[[Image:CMJ_Ligplot.png|150px|right|thumb|'''Fig.2''' CMJ Ligplot]]

<scene name='60/604479/Cmj/3'>CMJ</scene>

<scene name='60/604479/Cmj_binding_residues/2'>CMJ binding </scene>

[[Image:GOL_Ligplot.png|200px|left|thumb|'''Fig.3''' GOL Ligplot]]

<scene name='60/604479/Gol/1'>GOL Ligand</scene>

<scene name='60/604479/Gol_binding_residues/1'>GOL binding residues</scene>

[[Image:Cl_Ligplot.png|right|thumb|'''Fig.4''' Cl Ligplot]]

<scene name='60/604479/Cl/1'>Cl Ligand</scene>

<scene name='60/604479/Cl_binding_residue/1'>Cl binding residue</scene>

=== Natural ligands ===

<scene name='60/604479/Hydrophobic_residues/1'>hydrophobic residues</scene>

<scene name='60/604479/Kink/1'>kink</scene>

<scene name='60/604479/Acidic_residues/1'>acidic residues</scene>

== Related structures ==

These structures shown below representing the same protein with variable ligand and pH emphasize and illustrate the binding versatility of PBP.

*[[3fe8]] The same protein in complex with a serendipitous ligand soaked at pH 4.0 
*[[3fe9]] The same protein in complex with a serendipitous ligand soaked at pH 7.0 
*[[3cdn]] The same protein in apo form soaked at pH 4.0 
*[[2h8v]] The same protein in apo form at pH 5.5 
*[[3cz2]] The same protein in apo form at pH 7.0 
*[[3bfa]] The same protein in complex with the QMP at pH 5.5 
*[[3bfb]] The same protein in complex with the 9-ODA at pH 5.5 
*[[3bfh]] The same protein in complex with the HDOA at pH 5.5 
*[[3bjh]] The same protein in complex with the nBBSA at pH 5.5 
*[[3cyz]] The same protein in complex with the 9-ODA at pH 7.0 
*[[3cz0]] The same protein in complex with the QMP at pH 7.0 
*[[3cz1]] The same protein in complex with the nBBSA at pH 7.0 
*[[3cab]] The same protein in complex with the nBBSA soaked at pH 7.0 

== Relevance ==

== Structural highlights ==

This is a sample scene created with SAT to <scene name="/12/3456/Sample/1">color</scene> by Group, and another to make <scene name="/12/3456/Sample/2">a transparent representation</scene> of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.

</StructureSection>
== References for further information on the pheromone binding protein from Apis mellifera ==
<references/>