PhaP PhaC-HRT2truncImperial-College 2024
This part is designed by Team Imperial_College in iGEM 2024. Aiming to form an artificial organelle which serves as an enclosed chamber for natrual rubber production.
This composite part, with two CDS BBa_K208001 and BBa_K5416031 placed downstream of a pT7-LacO promoter BBa_K2406020, is designed to produce an artificial organelle of rubber particle inspired by the formation of polyhydroxyalkanoate (PHA) carboxysomes.
Background
Fig 1: How PhaC makes PHA granules[1][2]
Polyhydroxyalkanoate, is a hydrophobic polymer made in many prokaryotes, and recently becoming a famous material as it can be used as a bio-degradable plastic. Whilst the polymer is very hydrophobic in nature, it can be readily produced in large quantities in prokaryotic system, comparing to rubber. Insights into the structure of the enzyme producing the PHA, the PHA synthase (PhaC), reveals the existence of a hydrophobic domain close to the active site. This domain is shown to be involved in the granule formation of the PHA and with absence of this domain, little PHA is made in the cell. This appease to be similar to the issue observed with bioproduction of natural rubber, where losing anchorage of the molecule results in significant reduction of the total amount of rubber produced.
Fig 2: An illustration of how this part is designed to work
Inspired by the structure of PhaC, we questioned if the mechanism could be applied to the formation of rubber granules. Where the HRT2trunc (BBa_K5416000) is redesigned to be attached to the N terminus hydrophobic PHA binding domain of PhaC1. This would hypothetically capture the newly formed rubber chain and phase-separate the rubber granule with the rest of the cell. By introducing the other PHA-associated protein (PhaP), this structure can be then stabilized and become an ideal environment for rubber synthesis.
