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From 2011.igem.org

Latherin

Origin:

Latherin is a surfactant protein with detergent like properties.

Latherin was first isolated from the sweat of horses (Equus caballus). It was first described in the 1980s by John Beeley and David Eckersall, from the University of Glasgow.

Since being found in horse sweat, the protein has since been found in the salivary glands of several species of geographically separated equids. Sequence analysis has shown that it is a highly conserved protein.

Research has established the presence of latherin in the salivary glands, but has not found it in any other tissue.

Natural Function:

Of the three species of mammal that are known to thermoregulate by sweating, horses are unique in having sweat with such a high concentration of protein and low concentration of salt. Latherin is the most abundant protein found in horse sweat and is believed to be the cause of the foaming appearance of the sweat on exercising horses.

Latherin has long been suspected to be involved in thermoregulation. The protein is absorbed readily at hydrophobic surfaces, allowing them to become wettable. It will also cause a reduction in water surface tension. This function is presumably linked to the protein’s ability to facilitate evaporation of sweat from the pelt.

Latherin has also been found in the saliva of several species of equids. Its proposed function here is to aid in the wetting of food, which in turn aids chewing and the ability of salivary enzymes to digest the food.

Structure Information

Sequence analysis shows that latherin is a member of the PLUNC (“Palate, Lung and Nasal Epithelium Clone”) family. PLUNC represents a family of proteins, originally discovered in human. Their function is not entirely clear, but it is believed they may function in the innate immune response in the airways.

Analysis has shown that latherin has an unusual amino acid composition. The total number of hydrophobic amino acids is abnormally high, with leucine representing a large proportion of his. In fact, almost one in four residues is leucine. This is also true of the protein huPLUNC1, which has already been shown to have antimicrobial activity.

Biobrick:

The cDNA which encodes latherin has been cloned and a recombinant protein has been produced. This recombinant protein has stronger surfactant activity than the wild type protein. This can be expressed in E.coli.

We received the protein in a plasmid from researchers here at The University of Glasgow. It was subsequently amplified by PCR and the biobrick ends were added to it.

Biobrick with 6xHIS tag:

We have also created a version of the Latherin biobrick with a 6xHIS tag (Part:BBa_K660201).

This allows the protein to be isolated using affinity purification.

Use in DISColi

The latherin biobrick was produced to aid in the dispersal of biofilms.

As previously mentioned, latherin is able to temporality bind to hydrophobic surfaces and disrupt surface tension. It is therefore suspected that latherin may have a disruptive effect on biofilms.

References & Further Reading:

Beegley J, et al., 1986. Isolation and characterization of latherin, a surface-active protein from horse sweat.

Mcdonald R., et al., 2009. Latherin: A Surfactant Protein of Horse Sweat and Saliva

Kennedy M., Latherin: A Surface Active Protein from Horse Sweat

Kennedy M., 2011., Latherin and other biocompatible surfactant proteins

Goubran Botros H., et al 2001., Biochemical Characterisation and Surfactant Properties of Horse Allergens