Disease relevance of lipA

• The slr-1 mutation, which was mapped to min 99.6 of the E. coli chromosome, increased the lipoate requirement of lipA strains by 4-fold and appeared to define a gene encoding a lipoate-protein ligase [1].
• We report here the isolation of a Rhizobium etli gene involved in lipoic acid metabolism, the lipA gene, which complements a lipA mutant strain of Escherichia coli [2].
• Sequence similarity of the mature lipases (29% identity, 60% similarity) was observed mainly in the N-terminal 104 amino acids with the group II Pseudomonas lipases; no similarity to the two Streptomyces lipase sequences was found. lipA was also expressed in Escherichia coli under the control of lacZ promoter [3].
• The lipase-encoding gene, lipA, was cloned from genomic DNA into Streptomyces lividans TK23 with plasmid vector pIJ702 [3].
• The gene lipA coding for Lipase A from Bacillus subtilis was isolated by PCR amplification, cloned and expressed in Escherichia coli, Saccharomyces cerevisiae and Bacillus subtilis strains, using pBR322, YEplac112 and pUB110-derived vectors, respectively [4].

High impact information on lipA

• Recently, one substrate for lipoyl synthase has been shown to be the octanoylated derivative of the lipoyl-bearing subunit (E(2)) of the pyruvate dehydrogenase complex [Zhao, S., Miller, J. R., Jian, Y., Marletta, M. A., and Cronan, J. E., Jr. (2003) Chem. Biol. 10, 1293-1302] [5].
• Lipoyl synthase requires two equivalents of S-adenosyl-L-methionine to synthesize one equivalent of lipoic acid [5].
• Genetic and biochemical studies suggest that lipoyl synthase is a member of a newly established class of metalloenzymes that use S-adenosyl-l-methionine (AdoMet) as a source of a 5'-deoxyadenosyl radical (5'-dA(*)), which is an obligate intermediate in each reaction [5].
• Chromosomal DNA from the auxotrophs was amplified by PCR using primers derived from the DNA sequence of wild-type lipA and then sequenced [6].
• Upstream of lipA and in the same orientation, an open reading frame, orfA, is found whose deduced protein sequence (519 amino acids) shows similarity to various membrane-localized transporters [3].

Chemical compound and disease context of lipA

• In Escherichia coli, lipA was expressed in the form of inclusion bodies, which were subsequently solubilized by urea followed by dialysis [7].

Biological context of lipA

• The slr-7 mutation, which was mapped to min 15.25 of the chromosome, completely suppressed the lipoate requirement of lipA strains and defined a gene of unknown function in the synthesis of lipoic acid [1].
• Moreover, quantitative analysis of the lipA transcript by RNase protection assays indicated its down-regulation during entry into stationary phase [2].
• Two lipase-positive clones were identified; each recombinant plasmid had a 5.2-kb MboI insert that contained the complete lipA gene [3].
• Downstream of lipA and in the opposite orientation, an open reading frame, orfB (encoding a 199-amino-acid protein) is found, which shows no conspicuous sequence similarity to known proteins, other than an NAD and flavin adenine dinucleotide binding-site sequence [3].
• Co-expression of lipA with the isc operon approximately trebled the isolated yield of soluble LipA and resulted in efficient assembly of the Fe-S cluster [8].

Associations of lipA with chemical compounds

• Cells grown under strictly anaerobic conditions required the lipA and lipB gene products for the synthesis of a functional glycine cleavage system [9].
• Lipoyl(octanoyl)transferase (LipB) transfers the octanoyl chain from ACP to the target lysine acceptor, generating the substrate for lipoyl synthase (LS), which subsequently catalyzes insertion of both sulfur atoms into the C-6 and C-8 positions of the octanoyl chain [10].

Other interactions of lipA

• The translational initiation site of the lipA gene was established, and the lipB gene product was identified as a 25-kDa protein [9].
• With the objective of improving soluble holo-LipA expression, a series of multi-cistronic plasmids were constructed carrying lipA in combination with one of the three systems: groE/SL, trxA, or the isc operon [8].

Analytical, diagnostic and therapeutic context of lipA

• Molecular cloning of a light-inducible gene (lipA) encoding a novel pilin from Arthrobacter photogonimos [11].

References