Reference "Comparative genomics and functional analysis of the NiaP family uncover nicotinate transporters from bacteria, plants, and mammals"

Reference ID

54988

Title

Comparative genomics and functional analysis of the NiaP family uncover nicotinate transporters from bacteria, plants, and mammals

Source

Funct Integr Genomics, 2012, vol. 12, pp. 25-34

Authors (8)

Jeanguenin-L	Lara-Nunez-A
Rodionov-D-A	Osterman-A-L
Komarova-N-Y	Rentsch-D
Gregory-J-F-3rd	Hanson-A-D

Abstract

The transporter(s) that mediate uptake of nicotinate and its N-methyl derivative
trigonelline are not known in plants, and certain mammalian nicotinate
transporters also remain unidentified. Potential candidates for these missing
transporters include proteins from the ubiquitous NiaP family. In bacteria, niaP
genes often belong to NAD-related regulons, and genetic evidence supports a role
for Bacillus subtilis and Acinetobacter baumannii NiaP proteins in uptake of
nicotinate or nicotinamide. Other bacterial niaP genes are, however, not in NAD-
related regulons but cluster on the chromosome with choline-related (e.g.,
Ralstonia solanacearum and Burkholderia xenovorans) or thiamin-related (e.g.,
Thermus thermophilus) genes, implying that they might encode transporters for
these compounds. Radiometric uptake assays using Lactococcus lactis cells
expressing NiaP proteins showed that B. subtilis, R. solanacearum, and B.
xenovorans NiaP transport nicotinate via an energy-dependent mechanism.
Likewise, NiaP proteins from maize (GRMZM2G381453, GRMZM2G066801, and
GRMZM2G081774), Arabidopsis (At3g13050), and mouse (SVOP) transported
nicotinate; the Arabidopsis protein also transported trigonelline. In contrast,
T. thermophilus NiaP transported only thiamin. None of the proteins tested
transported choline or the thiazole and pyrimidine products of thiamin
breakdown. The maize and Arabidopsis NiaP proteins are the first nicotinate
transporters reported in plants, the Arabidopsis protein is the first
trigonelline transporter, and mouse SVOP appears to represent a novel type of
mammalian nicotinate transporter. More generally, these results indicate that
specificity for nicotinate is conserved widely, but not absolutely, among pro-
and eukaryotic NiaP family proteins.