Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Mol Microbiol. 2011 Apr;80(2):350-63. doi: 10.1111/j.1365-2958.2011.07598.x. Epub 2011 Mar 17.

A novel amidotransferase required for lipoic acid cofactor assembly in Bacillus subtilis.

Author information

  • 1Departments of Microbiology Biochemistry Chemistry Biology Interface Training Program, University of Illinois, Urbana, IL 61801, USA.

Abstract

In the companion paper we reported that Bacillus subtilis requires three proteins for lipoic acid metabolism, all of which are members of the lipoate protein ligase family. Two of the proteins, LipM and LplJ, have been shown to be an octanoyltransferase and a lipoate : protein ligase respectively. The third protein, LipL, is essential for lipoic acid synthesis, but had no detectable octanoyltransferase or ligase activity either in vitro or in vivo. We report that LipM specifically modifies the glycine cleavage system protein, GcvH, and therefore another mechanism must exist for modification of other lipoic acid requiring enzymes (e.g. pyruvate dehydrogenase). We show that this function is provided by LipL, which catalyses the amidotransfer (transamidation) of the octanoyl moiety from octanoyl-GcvH to the E2 subunit of pyruvate dehydrogenase. LipL activity was demonstrated in vitro with purified components and proceeds via a thioester-linked acyl-enzyme intermediate. As predicted, ΔgcvH strains are lipoate auxotrophs. LipL represents a new enzyme activity. It is a GcvH:[lipoyl domain] amidotransferase that probably uses a Cys-Lys catalytic dyad. Although the active site cysteine residues of LipL and LipB are located in different positions within the polypeptide chains, alignment of their structures show these residues occupy similar positions. Thus, these two homologous enzymes have convergent architectures.

© 2011 Blackwell Publishing Ltd.

PMID:
21338421
[PubMed - indexed for MEDLINE]
PMCID:
PMC3088481
Free PMC Article

Images from this publication.See all images (10)Free text

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Blackwell Publishing Icon for PubMed Central
    Loading ...
    Write to the Help Desk