title: Functional identification and expression of indole-3-pyruvate decarboxylase from Paenibacillus polymyxa E681.
abstract: Indole-3-acetic acid (IAA) is produced commonly by plants and many bacteria, however, little is known about the genetic basis involving the key enzymes of IAA biosynthetic pathways from Bacillus spp. IAA intermediates from the Gram-positive spore-forming bacterium Paenibacillus polymyxa E681 were investigated, which showed the existence of only an indole-3-pyruvic acid (IPA) pathway for IAA biosynthesis from the bacterium. Four open reading frames (ORFs) encoding indole-3-pyruvate decarboxylaselike proteins and putative indole-3-pyruvate decarboxylase (IPDC), a key enzyme in the IPA synthetic pathway, were found on the genome sequence database of P. polymyxa and cloned in Escherichia coli DH5alpha. One of the ORFs, PP2_01257, was assigned as probable indole-3-pyruvate decarboxylase. The ORF consisted of 1,743 nucleotides encoding 581 amino acids with a deduced molecular mass of 63,380 Da. Alignment studies of the deduced amino acid sequence of the ORF with known IPDC sequences revealed conservation of several amino acids in PP2_01257, essential for substrate and cofactor binding. Recombinant protein, gene product of the ORF PP2_01257 from P. polymyxa E681, was expressed in E. coli BL21 (DE3) as a glutathione S-transferase (GST)-fusion protein and purified to homogeneity using affinity chromatography. The molecular mass of the purified enzyme showed about 63 kDa, corresponding closely to the expected molecular mass of IPDC. The indole-3-pyruvate decarboxylase activity of the recombinant protein, detected by HPLC, using IPA substrate in the enzyme reaction confirmed the identity and functionality of the enzyme IPDC from the E681 strain.
authors.affiliation: Department of Microbiology, College of Natural Sciences, Kyungpook National University, Daegu, Korea.
authors.forename: Quyet-Tien
authors.initials: QT
authors.lastname: Phi
authors.forename: Yu-Mi
authors.initials: YM
authors.lastname: Park
authors.forename: Choong-Min
authors.initials: CM
authors.lastname: Ryu
authors.forename: Seung-Hwan
authors.initials: SH
authors.lastname: Park
authors.forename: Sa-Youl
authors.initials: SY
authors.lastname: Ghim
mesh_terms: D000595:Amino Acid Sequence; D001407:Bacillus / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D053898:Biosynthetic Pathways; D002262:Carboxy-Lyases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003001:Cloning, Molecular; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D007210:Indoleacetic Acids; C030737:indoleacetic acid; C068832:indolepyruvate decarboxylase; D002262:Carboxy-Lyases