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From Proteopedia

Revision as of 18:44, 26 April 2020

Ectatomin is a 2 chain polypeptide protein, belongs to the ectatomin-ET subfamily.Ectataomin produces the toxic effects of the venom from the Ectatomma tuberculatum ant.

Function

Ectatomin is the protein that causes the toxic effect of the venom. Ecataomin targets the cell membrane, creating pores that cause ion leakage and low membrane resistance. The pores created is due to the ectatomin channel forming ability. These channel/pores are formed selectively on the membrane, they occur at positive cis-potential locations. At these locations two ectatomin molecules must be present in order for the formation of a pore. The protein is able to insert itself into the membrane and interact with the protein kinases part of the signaling cascade. Though when raised to a higher concentration, the protein instead inhibits the autophosphorylation of pp60c-src protein tyrosine kinase. At this lower concentration ectatomin is able to enter the membrane but is not able to penetrate inside the cell. At higher concentrations which are required for hemolytic and cytolytic effects to occur the toxin acts more like a detergent similar to mellitin. Ectatomin causes the inhibition of the calcium channels. The toxin protein binds to the gated channel when it has changed two its mode 2. This mode is occurs when B-adrenergic stimulates the channel. The toxin can bind to mode 1 channels but seems to have a higher affinity for the channel after the B-adrenergic stimulation has occurred.^[1]

Process of Discovery

The Ectatomin protein structure was determined using MARDIGRAS program. It was able to create accurate distance constraints for protein to protein measurements. The DIANA program was used to find the disulfide bridges.The protein was ran through the CHARMm program for refinement and touchups. Us The rms deviation was .75 A for the heavy backbone atoms, for overall heavy atoms it was 1.25 A.

Ectatomma tuberculatum ant

The Ectatomma tuberculatum ant that produces the Ectatomin protein lives in the upper region of South America region and the lower North America region. This ant is one of the 15 species that make up the Ectatomma species. This ant normally builds nests on the ground around trees. These ants are built up around three type’s of ant.There are workers, microqueens(mircogynes), and queens(macrogynes). The queen are three times larger than mirco queens, though both queens can be inseminated. The queens are able to produce a larger amount of larva than mirco queens. The micro queens are also known as Ectatomma Parasiticum, these queen produce nearly identical larva as the queens but these microqueen larva are biased to the microqueen. When enough larva have been born the microqueens and her workers will attempt to usurp the colonies of the Ectatomma tuberculatum. The part of the body where the toxin originates is the venom gland. This gland is connected to a stinger which allows the ant to stab its prey and deliver the toxin. Though the main purpose of the toxin is to kill the prey or attacker,the venom can be used for colony asepsis, preventing infections in food and other ants.

For more information about the Ectatomma tuberculatum ant: https://www.antwiki.org/wiki/Ectatomma_tuberculatum

For more information about the Ectatomma patasiticum ant: https://www.antwiki.org/wiki/Ectatomma_parasiticum

Structural highlights

is a simple toxin protein, with a molecular weight of 7928 Da, pl 9.95).^[1] The protein is made up of two polypeptide chains, these chains are homologous and amphiphilic. The A chain is 37 amino acids and the B chain is 34 amino acid in length. The two chains are held together by a . The chains are made from antiparallel alpha helices, these two alpha helices are connected by a hinge made up form a disulfide bridge and four amino acids. This hinge region creates additional stability by forming a hairpin unit and helps the disulfide bonds stay stable.The PTMs that occur on this protein are disulfide bonds. These bonds connect the 12-34 sites of the A subunit. Also connect the 22 of subunit A to the 20 site of sub unit B. There is a final disulfide bond that connects the 10 site to the 32 site of subunit B. These are the bonds that hold the protein in the bundle shape that you see in the diagram.

References

1. ↑ ^{1.0 1.1} Pluzhnikov, Kirill, et al. “Analysis of Ectatomin Action on Cell Membranes.” FEBS Press, John Wiley & Sons, Ltd, 25 Dec. 2001, febs.onlinelibrary.wiley.com/doi/full/10.1046/j.1432-1327.1999.00426.x.

Arseniev, et al. “Three-Dimensional Structure of Ectatomin from Ectatomma Tuberculatum Ant Venom.” Journal of Biomolecular NMR, Kluwer Academic Publishers, 1 Jan. 1994, link.springer.com/article/10.1007/BF00227465.

“Ectatomin.” InterPro, ELIXIR Core Data Resource, www.ebi.ac.uk/interpro/entry/InterPro/IPR009458/.

Nolde, D E, et al. “Three-Dimensional Structure of Ectatomin from Ectatomma Tuberculatum Ant Venom.” Journal of Biomolecular NMR, U.S. National Library of Medicine, Jan. 1995, www.ncbi.nlm.nih.gov/pubmed/7881269?dopt=Abstract.

Reid, T Scott, et al. “Crystallographic Analysis of CaaX Prenyltransferases Complexed with Substrates Defines Rules of Protein Substrate Selectivity.” Journal of Molecular Biology, U.S. National Library of Medicine, 15 Oct. 2004, www.ncbi.nlm.nih.gov/pubmed/15451670.

Pluzhinikov, K A, et al. “Structure-Activity Study of the Basic Toxic Component of Venom from the Ant Ectatomma Tuberculatum.” Bioorganicheskaia Khimiia, U.S. National Library of Medicine, 1994, www.ncbi.nlm.nih.gov/pubmed/7826413?dopt=Abstract. Pluzhnikov, Kirill, et al. “Analysis of Ectatomin Action on Cell Membranes.” FEBS Press, John Wiley & Sons, Ltd, 25 Dec. 2001, febs.onlinelibrary.wiley.com/doi/full/10.1046/j.1432-1327.1999.00426.x.