PMID:24497982

Citation	Erbakan, M, Shen, YX, Grzelakowski, M, Butler, PJ, Kumar, M and Curtis, WR (2014) Molecular cloning, overexpression and characterization of a novel water channel protein from Rhodobacter sphaeroides. PLoS ONE 9:e86830
Abstract	Aquaporins are highly selective water channel proteins integrated into plasma membranes of single cell organisms; plant roots and stromae; eye lenses, renal and red blood cells in vertebrates. To date, only a few microbial aquaporins have been characterized and their physiological importance is not well understood. Here we report on the cloning, expression and characterization of a novel aquaporin, RsAqpZ, from a purple photosynthetic bacterium, Rhodobacter sphaeroides ATCC 17023. The protein was expressed homologously at a high yield (∼20 mg/L culture) under anaerobic photoheterotrophic growth conditions. Stopped-flow light scattering experiments demonstrated its high water permeability (0.17±0.05 cm/s) and low energy of activation for water transport (2.93±0.60 kcal/mol) in reconstituted proteoliposomes at a protein to lipid ratio (w/w) of 0.04. We developed a fluorescence correlation spectroscopy based technique and utilized a fluorescent protein fusion of RsAqpZ, to estimate the single channel water permeability of RsAqpZ as 1.24 (±0.41) x 10(-12) cm(3)/s or 4.17 (±1.38)×10(10) H2O molecules/s, which is among the highest single channel permeability reported for aquaporins. Towards application to water purification technologies, we also demonstrated functional incorporation of RsAqpZ in amphiphilic block copolymer membranes.
Links	PubMed PMC3909002 Online version:10.1371/journal.pone.0086830
Keywords
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
RHOS4:Q3J2P5		GO:0015250: water channel activity	ECO:0000314:		F		Figure 7 shows the average water permeability of the aquaporin to be 1.23±0.43×10−12 cm3/s	complete CACAO 10077

References

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