Pirin Regulates Pyruvate Catabolism by Interacting with the Pyruvate Dehydrogenase E1 Subunit and Modulating Pyruvate Dehydrogenase Activity
Resource
JOURNAL OF BACTERIOLOGY v.189 n.1 pp.109-118
Journal
JOURNAL OF BACTERIOLOGY
Journal Volume
v.189
Journal Issue
n.1
Pages
109-118
Date Issued
2007
Date
2007
Author(s)
SOO, PO-CHI
HORNG, YU-TZE
LAI, MENG-JIUN
WEI, JIUN-RUNG
HSIEH, SHANG-CHEN
CHANG, YUNG-LIN
TSAI, YU-HUAN
LAI, HSIN-CHIH
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 pirin(Sm), gene. Functional analyses showed that both PDH El subunit activity and PDH enzyme complex activity are inhibited by the pirin(Sm) gene in S. marcescens CH-1. The S. marcescens CH-1 pirin(Sm) gene was subsequently mutated by insertion- deletion homologous recombination. Accordingly, the PDH Ell and PDH enzyme complex activities and cellular ATP concentration increased up to 250%, 140%, and 220%, respectively, in the S. marcescens CH-1 pirin(Sm) mutant. Concomitantly, the cellular NADH/ NAD(+) ratio increased in the pirin(Sm) mutant, indicating increased tricarboxylic acid (TCA) cycle activity. Our results show that the pirin( Sm) gene plays a regulatory role in the process of pyruvate catabolism to acetyl coenzyme A through interaction with the PDH El subunit and inhibiting PDH enzyme complex activity in S. marcescens CH-1, and they suggest that pirin(Sm) is an important protein involved in determining the direction of pyruvate metabolism towards either the TCA cycle or the fermentation pathways.
Subjects
CELL-ENVELOPE ARCHITECTURE
ESCHERICHIA-COLI
MULTIENZYME COMPLEX
SERRATIA-MARCESCENS
SWARMING MOTILITY
NUCLEAR- PROTEIN