Pirin regulates pyruvate catabolism by interacting with the pyruvate dehydrogenase E1 subunit and modulating pyruvate dehydrogenase activity

Po Chi Soo, Yu Tze Horng, Meng Jiun Lai, Jun Rong Wei, Shang Chen Hsieh, Yung Lin Chang, Yu Huan Tsai, Hsin Chih Lai*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

The protein pirin, which is involved in a variety of biological processes, is conserved from prokaryotic microorganisms, fungi, and plants to mammals. It acts as a transcriptional cofactor or an apoptosis-related protein in mammals and is involved in seed germination and seedling development in plants. In prokaryotes, while pirin is stress induced in cyanobacteria and may act as a quercetinase in Escherichia coli, the functions of pirin orthologs remain mostly uncharacterized. We show that the Serratia marcescens pirin (pirin Sm) gene encodes an ortholog of pirin protein. Protein pull-down and bacterial two-hybrid assays followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrospray ionization-tandem mass spectrometry analyses showed the pyruvate dehydrogenase (PDH) E1 subunit as a component interacting with the pirinSm gene. Functional analyses showed that both PDH E1 subunit activity and PDH enzyme complex activity are inhibited by the pirinSm gene in S. marcescens CH-1. The S. marcescens CH-1 pirinSm gene was subsequently mutated by insertion-deletion homologous recombination. Accordingly, the PDH E1 and PDH enzyme complex activities and cellular ATP concentration increased up to 250%, 140%, and 220%, respectively, in the S. marcescens CH-1 pirinSm mutant. Concomitantly, the cellular NADH/NAD+ ratio increased in the pirinSm mutant, indicating increased tricarboxylic acid (TCA) cycle activity. Our results show that the pirinSm gene plays a regulatory role in the process of pyruvate catabolism to acetyl coenzyme A through interaction with the PDH E1 subunit and inhibiting PDH enzyme complex activity in S. marcescens CH-1, and they suggest that pirinSm is an important protein involved in determining the direction of pyruvate metabolism towards either the TCA cycle or the fermentation pathways.

Original languageEnglish
Pages (from-to)109-118
Number of pages10
JournalJournal of Bacteriology
Volume189
Issue number1
DOIs
StatePublished - Jan 2007

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