Linked Life Data

17669423

Source:http://linkedlifedata.com/resource/pubmed/id/17669423

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2007-9-3
pubmed:databankReference
pubmed:abstractText
Angucyclines are aromatic polyketides produced in Streptomycetes via complex enzymatic biosynthetic pathways. PgaE and CabE from S. sp PGA64 and S. sp. H021 are two related homo-dimeric FAD and NADPH dependent aromatic hydroxylases involved in the early steps of the angucycline core modification. Here we report the three-dimensional structures of these two enzymes determined by X-ray crystallography using multiple anomalous diffraction and molecular replacement, respectively, to resolutions of 1.8 A and 2.7 A. The enzyme subunits are built up of three domains, a FAD binding domain, a domain involved in substrate binding and a C-terminal thioredoxin-like domain of unknown function. The structure analysis identifies PgaE and CabE as members of the para-hydroxybenzoate hydroxylase (pHBH) fold family of aromatic hydroxylases. In contrast to phenol hydroxylase and 3-hydroxybenzoate hydroxylase that utilize the C-terminal domain for dimer formation, this domain is not part of the subunit-subunit interface in PgaE and CabE. Instead, dimer assembly occurs through interactions of their FAD binding domains. FAD is bound non-covalently in the "in"-conformation. The active sites in the two enzymes differ significantly from those of other aromatic hydroxylases. The volumes of the active site are significantly larger, as expected in view of the voluminous tetracyclic angucycline substrates. The structures further suggest that substrate binding and catalysis may involve dynamic rearrangements of the middle domain relative to the other two domains. Site-directed mutagenesis studies of putative catalytic groups in the active site of PgaE argue against enzyme-catalyzed substrate deprotonation as a step in catalysis. This is in contrast to pHBH, where deprotonation/protonation of the substrate has been suggested as an essential part of the enzymatic mechanism.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
372
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
633-48
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed-meshheading:17669423-4-Hydroxybenzoate-3-Monooxygenase, pubmed-meshheading:17669423-Amino Acid Sequence, pubmed-meshheading:17669423-Binding Sites, pubmed-meshheading:17669423-Catalysis, pubmed-meshheading:17669423-Crystallography, X-Ray, pubmed-meshheading:17669423-Flavin-Adenine Dinucleotide, pubmed-meshheading:17669423-Mixed Function Oxygenases, pubmed-meshheading:17669423-Models, Molecular, pubmed-meshheading:17669423-Molecular Sequence Data, pubmed-meshheading:17669423-Oxidation-Reduction, pubmed-meshheading:17669423-Polycyclic Compounds, pubmed-meshheading:17669423-Protein Structure, Quaternary, pubmed-meshheading:17669423-Protein Structure, Secondary, pubmed-meshheading:17669423-Protein Subunits, pubmed-meshheading:17669423-Sequence Alignment, pubmed-meshheading:17669423-Static Electricity, pubmed-meshheading:17669423-Streptomyces, pubmed-meshheading:17669423-Substrate Specificity
pubmed:year
2007
pubmed:articleTitle
Crystal structures of two aromatic hydroxylases involved in the early tailoring steps of angucycline biosynthesis.
pubmed:affiliation
Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden.
pubmed:publicationType
Journal Article