Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.16.2 (PCP)
 3,761 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The iron-chelating catechol siderophore vibriobactin of the pathogenic Vibrio cholerae is assembled by a four-subunit, ten-domain nonribosomal peptide synthetase system, VibE, VibB, VibH, and VibF, using 2,3-dihydroxybenzoate and L-threonine as precursors to two (dihydroxyphenyl)methyloxazolinyl groups in amide linkage on a norspermidine scaffold. We have utilized site-specific and domain-deletion mutagenesis to map the heterocyclization and primary and secondary amine acylation activities of the six-domain (Cy1-Cy2-A-C1-PCP-C2) VibF subunit. We have found that Cy2 is capable of and limited to the condensation (amide bond formation) step of the three-step heterocyclization process, while Cy1 is capable of and limited to the final processing (cyclization/dehydration) steps to the completed heterocycle. Additionally, we have observed that the C2 domain functions in both N(9) (primary amine) acylation and N(5) (secondary amine) acylation of the (dihydroxybenzoyl)norspermidine substrate, leaving no catalytic role for the C1 domain, a conclusion confirmed with the formation of vibriobactin in a C1-deficient system. Thus VibF is an NRPS with two domains, Cy1 and Cy2, that perform a function otherwise performed by one and with one domain, C2, that performs a function otherwise performed by two. While C2 appeared to tolerate uncyclized threonine in place of the usual heterocycle in primary amine acylation, it refused this replacement in the corresponding donor substrate in secondary amine acylation.
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PMID:Catalytic mapping of the vibriobactin biosynthetic enzyme VibF. 1177 22

Nonribosomal peptide synthetases (NRPS), fatty acid synthases (FAS), and polyketide sythases (PKS) are multimodular enzymatic assembly lines utilized in natural product biosynthesis. Previous data on FAS and PKS subunits have indicated that they are homodimers and that some of their catalytic functions can work in trans. When NRPS assembly lines have been probed for comparable formation of stable oligomers, no evidence had been forthcoming that species other than monomer forms were active. In this work we focus on the six-domain (Cy1-Cy2-A-C1-PCP-C2) enzyme VibF from the vibriobactin synthetase assembly line, which contains three other proteins, VibB, VibE, and VibH, that--when purified and mixed with VibF and the substrates ATP, threonine, 2,3-dihydroxybenzoate (DHB), and norspermidine--produce the iron chelator vibriobactin. Using a deletion of the Cy1 domain and separate inactivating mutations in the Cy2, A, PCP, and C2 domains of VibF, we report regain of catalytic activity upon mutant protein mixing that argues for heterodimer formation, stable for hundreds to thousands of catalytic cycles, with acyl chain processing and transfer around blocked domains. Ultracentrifugation data likewise confirm a dimeric structure for VibF and establish that domains within NRPS dimeric modules can act on acyl chains in trans. The results described here are the first indication for an NRPS subunit that homodimerization can occur and that there is a continuum of functional oligomerization states between monomers and dimers in nonribosomal peptide synthetases.
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PMID:Dimeric structure of the six-domain VibF subunit of vibriobactin synthetase: mutant domain activity regain and ultracentrifugation studies. 1253 89

In this study, the isolation, the structural characterization, and the elucidation of the biosynthetic origin of heterobactins, catecholate-hydroxamate mixed-type siderophores from Rhodococcus erythropolis PR4, are reported. The structure elucidation of heterobactin A was accomplished via MS(n) analysis and NMR spectroscopy and revealed the noteworthy presence of a peptide bond between the guanidine group of an arginine residue and a 2,3-dihydroxybenzoate moiety. The two heterobactin S1 and S2 variants are derivatives of heterobactin A that have sulfonation modifications on the aromatic rings. The bioinformatic analysis of the R. erythropolis PR4 genome and the subsequent genetic and biochemical characterization of the putative biosynthetic machinery identified the gene cluster responsible for the biosynthesis of the heterobactins. Interestingly, the HtbG NRPS presents an unprecedented C-PCP-A domain organization within the second module of the synthetase that may help the correct elongation of the peptide intermediate. Finally, the present work revises the structure of heterobactin A that was described by Carrano et al. in 2001.
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PMID:Structural characterization of the heterobactin siderophores from Rhodococcus erythropolis PR4 and elucidation of their biosynthetic machinery. 2427 68