Affiliation:
1. Laboratorio de Biotecnolog�a Bacteriana, Instituto de Ciencia y Tecnolog�a de Alimentos y Nutrici�n, ICTAN-CSIC, Madrid, Spain
Abstract
Lactobacillus plantarum
is a lactic acid bacterium able to degrade tannins by the subsequent action of tannase and gallate decarboxylase enzymes. The gene encoding tannase had previously been identified, whereas the gene encoding gallate decarboxylase is unknown. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of gallic-acid induced
L. plantarum
extracts showed a 54-kDa protein which was absent in the uninduced cells. This protein was identified as Lp_2945, putatively annotated UbiD. Homology searches identified
ubiD
-like genes located within three-gene operons which encoded the three subunits of nonoxidative aromatic acid decarboxylases.
L. plantarum
is the only bacterium in which the
lpdC
(
lp_2945
) gene and the
lpdB
and
lpdD
(
lp_0271
and
lp_0272
) genes are separated in the chromosome. Combination of extracts from recombinant
Escherichia coli
cells expressing the
lpdB
,
lpdC
, and
lpdC
genes demonstrated that LpdC is the only protein required to yield gallate decarboxylase activity. However, the disruption of these genes in
L. plantarum
revealed that the
lpdB
and
lpdC
gene products are essential for gallate decarboxylase activity. Similar to
L. plantarum
tannase, which exhibited activity only in esters derived from gallic and protocatechuic acids, purified His6-LpdC protein from
E. coli
showed decarboxylase activity against gallic and protocatechuic acids. In contrast to the tannase activity, gallate decarboxylase activity is widely present among lactic acid bacteria. This study constitutes the first genetic characterization of a gallate decarboxylase enzyme and provides new insights into the role of the different subunits of bacterial nonoxidative aromatic acid decarboxylases.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
74 articles.
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