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Advisor(s)
Abstract(s)
Plant Nodulin 26-like Intrinsic Proteins (NIPs) are multifunctional membrane channels
of the Major Intrinsic Protein (MIP) family. Unlike other homologs, they have low intrinsic water
permeability. NIPs possess diverse substrate selectivity, ranging from water to glycerol and to
other small solutes, depending on the group-specific amino acid composition at aromatic/Arg (ar/R)
constriction. We cloned three NIPs (NIP1;1, NIP5;1, and NIP6;1) from grapevine (cv. Touriga
Nacional). Their expression in the membrane of aqy-null Saccharomyces cerevisiae enabled their
functional characterization for water and glycerol transport through stopped-flow spectroscopy.
VvTnNIP1;1 demonstrated high water as well as glycerol permeability, whereas VvTnNIP6;1 was
impermeable to water but presented high glycerol permeability. Their transport activities were
declined by cytosolic acidification, implying that internal-pH can regulate NIPs gating. Furthermore,
an extension of C-terminal in VvTnNIP6;1M homolog, led to improved channel activity, suggesting
that NIPs gating is putatively regulated by C-terminal. Yeast growth assays in the presence of diverse
substrates suggest that the transmembrane flux of metalloids (As, B, and Se) and the heavy metal (Cd)
are facilitated through grapevine NIPs. This is the first molecular and functional characterization of
grapevine NIPs, providing crucial insights into understanding their role for uptake and translocation
of small solutes, and extrusion of toxic compounds in grapevine
Description
Keywords
aquaporin grapevine Saccharomyces cerevisiae NIPs metalloids glycerol
Pedagogical Context
Citation
Int. J. Mol. Sci. 2020, 21, 663
Publisher
MDPI