Exceptional characteristics of heterotetrameric (α₂β₂) E1p of the pyruvate dehydrogenase complex fromZymomonas mobilis: expression from an own promoter and a lipoyl domain in E1β

Abstract

In the pyruvate dehydrogenase complex (PDHC) of Zymomonas mobilis the beta subunit of the pyruvate dehydrogenase (E1p) as well as the acetyltransferase (E2p) contain an N-terminal lipoyl domain. Both lipoyl domains were acetylated in vitro using 2-14C-pyruvate as a substrate, demonstrating that both lipoyl domains can accept acetyl groups from the E1 component. As previously shown the structural genes (pdhA alpha beta, pdhB, lpd) encoding the pyruvate dehydrogenase complex of Z. mobilis are located in two distinct gene clusters, pdhA alpha beta and pdhB-orf2-lpd (U. Neveling et al. (1998) J. Bacteriol. 180, 1540-1548). Analysis of pdh gene expression using lacZ fusions revealed that the DNA fragments upstream of pdhA alpha, pdhB and lpd each have promoter activities. These pdh promoter activities were 7-30-fold higher in Z. mobilis than in Escherichia coli.

A Novel Lipoate-Protein Ligase, Mhp-LplJ, Is Required for Lipoic Acid Metabolism in Mycoplasma hyopneumoniae

“…In most prokaryotic species, the LDs of PDH are always located in the E2 subunit dihydrolipoamide acetyltransferase (PdhC) (Perham, 2000). There are a few exceptions, such as the cases in Alcaligenes eutrophus (Hein and Steinbüchel, 1994) and Neisseria meningitidis (Bringas and Fernandez, 1995), where LDs were found in E3 subunit PdhD, while in Zymomonas mobilis, LDs were detected in pyruvate dehydrogenase E1 component subunit alpha (PdhA) (Ute et al, 1999). Our results indicated that the LD of M. hyopneumoniae PDH is in the PdhD subunit (Figures 2, 4).…”