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The Bacterial signal transduction protein GlnB regulates the committed step in fatty acid biosynthesis by acting as a dissociable regulatory subunit of acetyl‐ CoA carboxylase
Author(s) -
Gerhardt Edileusa C.M.,
Rodrigues Thiago E.,
MüllerSantos Marcelo,
Pedrosa Fabio O.,
Souza Emanuel M.,
Forchhammer Karl,
Huergo Luciano F.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12912
Subject(s) - biology , acetyl coa carboxylase , biochemistry , protein subunit , pyruvate carboxylase , fatty acid synthesis , transferase , biosynthesis , enzyme , acetyl coa , fatty acid , gene
Summary Biosynthesis of fatty acids is one of the most fundamental biochemical pathways in nature. In bacteria and plant chloroplasts, the committed and rate‐limiting step in fatty acid biosynthesis is catalyzed by a multi‐subunit form of the acetyl‐ CoA carboxylase enzyme ( ACC ). This enzyme carboxylates acetyl‐ CoA to produce malonyl‐ CoA , which in turn acts as the building block for fatty acid elongation. In E scherichia coli , ACC is comprised of three functional modules: the biotin carboxylase ( BC ), the biotin carboxyl carrier protein ( BCCP ) and the carboxyl transferase ( CT ). Previous data showed that both bacterial and plant BCCP interact with signal transduction proteins belonging to the P II family. Here we show that the GlnB paralogues of the P II proteins from E . coli and A zospirillum brasiliense , but not the GlnK paralogues, can specifically form a ternary complex with the BC‐BCCP components of ACC . This interaction results in ACC inhibition by decreasing the enzyme turnover number. Both the BC‐BCCP ‐ GlnB interaction and ACC inhibition were relieved by 2‐oxoglutarate and by GlnB uridylylation. We propose that the GlnB protein acts as a 2‐oxoglutarate‐sensitive dissociable regulatory subunit of ACC in Bacteria.