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. 454 491-499

Ämneskategorier

Biokemi och molekylärbiologi

DOI

10.1042/bj20130377