[Seminars] PSB event reminder
contact at psb.vib-ugent.be
contact at psb.vib-ugent.be
Sun Jun 5 11:10:01 CEST 2011
Calendar Name: seminars
Scheduled for: Tuesday, June 7 2011, 11:00 - 12:30
Event text: Prof François Chaumont
Institut des Sciences de la Vie
Université catholique de Louvain
Louvain-la-Neuve
Belgium
Details: Plasma membrane aquaporins: a highly regulated plumbing
system
ABSTRACT
Aquaporins are channels facilitating the movement of
water and/or uncharged solutes across membranes in all
kingdoms of life. Plant aquaporins constitute a large
and highly divergent protein family, and members of
several subfamilies are found in the plasma membrane.
Recently, we characterized proteins from a new subfamily
(XIP or X Intrinsic proteins) found in Solanaceae but
absent from Arabidopsis and monocots and showed that
they facilitate the transport of many uncharged
substrates. Besides this new aquaporin subfamily, the
most studied plant plasma membrane aquaporins are the
PIPs (Plasma membrane Intrinsic Proteins) that control
cellular water movement in many different physiological
processes. Using molecular and biophysical approaches,
we showed that the expression and activity of the PIPs
are regulated in Zea mays roots and leaves according to
the developmental stages, day/night cycle and in
response to short-term osmotic stress. Beyond the
initial regulatory step of controlling gene and protein
expression, different mechanisms have been reported to
regulate the traffic and gating of PIPs. Maize
aquaporins belonging to PIP1 and PIP2 groups formed
hetero-oligomers to regulate the traffic of ZmPIP1 from
the endoplasmic reticulum to the plasma membrane. In
addition, a conserved cysteine residue located in an
extra-cytosolic loop is involved in a disulfide bridge
formation between two monomers forming a dimer. The
delivery of ZmPIP2s to the plasma membrane involves also
interaction with the syntaxin SYP121. Altogether the
data point toward a complex and highly integrated
regulation of PIP trafficking and activity in the
maintenance of cellular water homeostasis.
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