What is PcaK?
PcaK is a bacterial membrane transporter that utitlises the proton motive force to import aromatic acids, primarily 4-hydroxybenzoate and protocatechuate. It belongs to the vast major facilitator superfamily as a member of the aromatic acid:H+ symporters, and the use of bioinformatics has identified PcaK homologues across multiple bacterial phyla. Interestingly, PcaK has also been shown to play a role not just in transport but also chemotaxis - though the mechanism by which it does so remains unknown. AAHS are thought to comprise of 12 transmembrane helices, with conserved sequences at the 2-3 and 8-9 cytoplasmic loops. The predicted membrane topology of PcaK from Pseudomonas putida can be viewed here (Ditty, J.L. and C.S. Harwood, J. Bacteriol., 2002.) which displays proposed hydrophobic regions, functionally important residues and conserved regions between the AAHS family.
Little is known for certain about the molecular structure and mechanism of PcaK so it's pretty exciting that I may contribute towards this!
What's the relevance of the research?
By understanding how aromatic acids are acquired from the environment we can gain further insight into the the degradation of aromatic compounds - this may lead to development of novel bioremediation strategies of aromatic pollutants. In addition, there are potential consequences for advances in biofuel production. The plant heteropolymer lignin, which is the most abundant aromatic compound on earth, may provide a favorable source for biofuels such as bioethanol if an efficient degradation and production method can be designed to do so.
|The chemical structure of lignin - a significant constituent of Earth's biomass|
|Ready to rock and roll|
References and further reading