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Related Concept Videos

Repressible Operon: trp Operon01:21

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The trp operon in Escherichia coli exemplifies a repressible operon. It regulates the synthesis of tryptophan through repressor-mediated transcriptional control and attenuation. This dual regulatory mechanism ensures tryptophan biosynthesis occurs only when needed, conserving cellular resources.Structure of the trp OperonThe trp operon consists of five structural genes (trpE, trpD, trpC, trpB, and trpA) that encode enzymes for tryptophan biosynthesis. These genes are transcribed as a single...
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Transcriptional attenuation occurs when RNA transcription is prematurely terminated due to the formation of a terminator mRNA hairpin structure.  Bacteria use these hairpins to regulate the transcription process and control the synthesis of several amino acids including histidine, lysine, threonine, and phenylalanine. Transcription attenuation takes place in the non-coding regions of mRNA.
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Amino acid biosynthesis is essential for cell growth, protein synthesis, and metabolic regulation. Cells generate essential and non-essential amino acids from metabolic intermediates to sustain vital biological functions. These intermediates originate from key metabolic pathways: glycolysis, the tricarboxylic acid (TCA) cycle, and the pentose phosphate pathway. Important precursors include α-ketoglutarate, pyruvate, oxaloacetate, phosphoenolpyruvate, and erythrose-4-phosphate, which...
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Chloroplasts are triple membrane structures with an outer membrane, an inner membrane, and a thylakoid membrane, each containing distinct metabolite transporters, membrane translocons, and enzymes. Appropriate sorting and translocating these proteins to their correct membrane systems is essential for chloroplast function.
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Related Experiment Video

Updated: Sep 9, 2025

PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase
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PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase

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Peptidic Tryptophan Halogenation by a Promiscuous Flavin-Dependent Enzyme.

Andrew J Rice1,2, Mayuresh G Gadgil2, Paola Bisignano3

  • 1Department of Biochemistry, Vanderbilt University School of Medicine-Basic Science, Department of Chemistry, Vanderbilt University, Nashville, TN, 37232, USA.

Angewandte Chemie (International Ed. in English)
|August 30, 2025
PubMed
Summary
This summary is machine-generated.

Researchers identified a versatile enzyme, ChlH (flavin-dependent halogenase), that can modify internal amino acids in peptides. This discovery broadens the potential for enzymatic peptide synthesis and modification in biotechnology.

Keywords:
BiocatalysisChlorineHalogenationPeptideProteins

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Area of Science:

  • Biochemistry
  • Enzymology
  • Synthetic Biology

Background:

  • Enzymatic modifications of amino acids are crucial but often limited by enzyme specificity.
  • Flavin-dependent halogenases (FDHs) typically modify specific peptides or peptide termini.
  • The narrow substrate scope and cofactor requirements of known FDHs limit their synthetic applications.

Purpose of the Study:

  • To characterize ChlH, a novel flavin-dependent halogenase from the chlorolassin biosynthetic gene cluster.
  • To investigate the substrate scope and catalytic activity of ChlH.
  • To explore the potential of ChlH for broad peptide and protein modification.

Main Methods:

  • Enzyme characterization of ChlH.
  • Scanning mutagenesis of the substrate peptide ChlA.
  • Molecular dynamics simulations.
  • Halogenation assays on diverse peptide substrates, including RiPPs and pharmacologically relevant peptides.
  • Cell-free biosynthetic assays.

Main Results:

  • ChlH, unlike other FDHs, efficiently halogenates internal tryptophan (Trp) residues in peptides, in addition to N- and C-terminal Trp.
  • Mutagenesis and simulations revealed insights into substrate recognition and specificity, explaining limitations in native chlorolassin biosynthesis.
  • Wild-type ChlH demonstrated broad applicability, successfully halogenating various peptide and protein substrates.
  • Cell-free assays elucidated ChlH's substrate preferences, highlighting its promiscuity.

Conclusions:

  • ChlH exhibits a unique and broad substrate specificity among FDHs, enabling modification of internal Trp residues in diverse peptide sequences.
  • The promiscuity of ChlH suggests significant potential for its application in modifying a wide range of peptide and protein substrates.
  • This enzyme represents a valuable tool for synthetic biology and biotechnology, facilitating novel peptide modifications.