Mercury increases water permeability of a plant aquaporin through a non-cysteine-related mechanism
Artikel i vetenskaplig tidskrift, 2013
Water transport across cellular membranes is mediated by a family of membrane proteins known as AQPs (aquaporins). AQPs were first discovered on the basis of their ability to be inhibited by mercurial compounds, an experiment which has followed the AQP field ever since. Although mercury inhibition is most common, many AQPs are mercury insensitive. In plants, regulation of AQPs is important in order to cope with environmental changes. Plant plasma membrane AQPs are known to be gated by phosphorylation, pH and Ca2+. We have previously solved the structure of the spinach AQP SoPIP2;1 (Spinacia oleracea plasma membrane intrinsic protein 2; 1) in closed and open conformations and proposed a mechanism for how this gating can be achieved. To study the effect of mercury on SoPIP2; 1 we solved the structure of the SoPIP2;1-mercury complex and characterized the water transport ability using proteoliposomes. The structure revealed mercury binding to three out of four cysteine residues. In contrast to what is normally seen for AQPs, mercury increased the water transport rate of SoPIP2; 1, an effect which could not be attributed to any of the cysteine residues. This indicates that other factors might influence the effect of mercury on SoPIP2; 1, one of which could be the properties of the lipid bilayer.
proteoliposome assay
divalent-cations
channel protein
X-
biochimica et biophysica acta
eston gm
membrane cholesterol content
plasma-membrane
aquaporin
transport
1993
eston gm
v986
v256
molecular-cloning
1992
p385
v268
basis
p191
mercury
insensitive aquaporin
ph
journal of biological chemistry
plasma membrane intrinsic protein
1989
science
p17
lnomdedieu m
functional-analysis
structural
water transport
Författare
Anna Frick
Göteborgs universitet
Michael Järvå
Göteborgs universitet
Mikael Ekvall
Göteborgs universitet
Povilas Uzdavinys
Göteborgs universitet
Anna Maria Nyblom
Göteborgs universitet
Susanna Törnroth-Horsefield
Göteborgs universitet
Biochemical Journal
0264-6021 (ISSN) 1470-8728 (eISSN)
Vol. 454 pt 3 491-499Ämneskategorier
Biokemi och molekylärbiologi
DOI
10.1042/bj20130377