《病原生物学（医学微生物学）》课程教学课件（英文）04_Microbial Metabolism

Section IFundaments of MicrobiologyMicrobial MetabolismSHIHEZI UNIVERSITY

Section I Fundaments of Microbiology Microbial Metabolism SHIHEZI UNIVERSITY

KEY TERMSFocal metaboliteGlucosePyruvateFermentationRespirationTricarboxylic acid (TCA) cycle or Krebs cycleOxidative phosphorylationGlyoxylate pathwaySHIHEZI UNIVERSITY

KEY TERMS Focal metabolite Glucose Pyruvate Fermentation Respiration Tricarboxylic acid (TCA) cycle or Krebs cycle Oxidative phosphorylation Glyoxylate pathway SHIHEZI UNIVERSITY

ROLE OF METABOLISMINBIOSYNTHESIS & GROWTHMicrobial growth requires the polymerization ofbiochemical building blocks into proteinsnucleic acids, polysaccharides, and lipids The building blocks must come preformed in thegrowth medium or must be synthesized by thegrowing cellsBiosynthetic polymerization reactions demand thetransfer of anhydride bonds from ATPSHIHEZI UNIVERSITY

ROLE OF METABOLISM IN BIOSYNTHESIS & GROWTH  Microbial growth requires the polymerization of biochemical building blocks into proteins, nucleic acids, polysaccharides, and lipids  The building blocks must come preformed in the growth medium or must be synthesized by the growing cells  Biosynthetic polymerization reactions demand the transfer of anhydride bonds from ATP SHIHEZI UNIVERSITY

Focal Metabolite: The few precursors for the biosyntheticorigins of building blocks and coenzymesFocal metaboliteIntermediatesEnd productsPolysaccharidesHexose phosphatesNucleic acidsHistidinePentosephosphatesTryptophanGlucose 6-phosphate→PhenyalanineTetrosephosphate→ChorismateTyrosine+ LipidsTriose phosphatesGlycine3-Phosphoglycerate→Serine→ CysteineTryptophanFigure61Biosyntheticendproductsfomedfomglucos6-phosphateCarbohydratephophateestersofvaryingchainlengthserveasintermediatesinthebiosyntheticpathwaysSHIHEZIUNIVERSITY

Focal Metabolite: The few precursors for the biosynthetic origins of building blocks and coenzymes SHIHEZI UNIVERSITY

Four Categories of MicrobialMetabolismPathways for the interconversion of focametabolitesAssimilatory pathways for the formationof focal metabolitesBiosynthetic sequences for the conversionof focal metabolites to end productsPathways that yield metabolic energySHIHEZI UNIVERSITY

Four Categories of Microbial Metabolism 1. Pathways for the interconversion of focal metabolites 2. Assimilatory pathways for the formation of focal metabolites 3. Biosynthetic sequences for the conversion of focal metabolites to end products 4. Pathways that yield metabolic energy SHIHEZI UNIVERSITY

Macromolecule SynthesisWhen provided with building blocks and a source ofmetabolic energy, a cell synthesizes macromolecules The sequence of building blocks within a macromoleculeis determined in one of two ways In nucleic acids and proteins, it is template-directedDNA serves as the template forits own synthesis and for thesynthesis of the various types of RNAmessenger RNA serves as thetemplateforthesynthesis of proteinsIn carbohydrates and lipids, the arrangement of building blocks isdetermined entirely by enzyme specificitiesOnce the macromolecules have been synthesized, theyself-assemble to form the supramolecular structures of thecell, eg, ribosomes, membranes, cell wall, flagella andpiliSHIHEZIUNIVERSITY

Macromolecule Synthesis  When provided with building blocks and a source of metabolic energy, a cell synthesizes macromolecules  The sequence of building blocks within a macromolecule is determined in one of two ways  In nucleic acids and proteins, it is template-directed  DNA serves as the template for its own synthesis and for the synthesis of the various types of RNA  messenger RNA serves as the template for the synthesis of proteins.  In carbohydrates and lipids, the arrangement of building blocks is determined entirely by enzyme specificities  Once the macromolecules have been synthesized, they self-assemble to form the supramolecular structures of the cell, eg, ribosomes, membranes, cell wall, flagella, and pili SHIHEZI UNIVERSITY

Metabolism RegulationThe rate of macromolecular synthesis andthe activity of metabolic pathways must beregulated so that biosynthesis is balancedSHIHEZI UNIVERSITY

Metabolism Regulation  The rate of macromolecular synthesis and the activity of metabolic pathways must be regulated so that biosynthesis is balanced SHIHEZI UNIVERSITY

Focal metaboliteEnd productsIntermediatesPolysaccharidesHexose phosphatesNucleic acids二+HistidinePentose phosphatesTryptophanGlucose6-phosphate+PhenylalanineTetrosephosphate→ChorismateTyrosineTriose phosphatesLipidsGlycine3-Phosphoglycerate+Serine+CysteineTryptophanFigure6Biosyntheticendproductsfomedfomglucos6phophateCarbohydratephophateestersofvarying chain length serve as intermediates in the biosynthetic pathways.SHIHEZI UNIVERSITY

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Focal metabolteIntermediatesEnd productsTriose phosphatesGlycine+SerineCysteine3-PhosphoglycerateTryptophanChorismate+ PhenylalanineTyrosinePhosphoenolpyruvatePolysaccharidesAlanine★ValinePyruvateIsoleucineAcetyl-CoA+LipidsFigure62BiosyntheticendproductfomedfomphosphoenolpyruateSHIHEZIUNIVERSITY

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Focal metaboliteEnd productsAsparagineAspartateThreonine→IsoleucineOxaloacetateMethionineCoenzymesPyimidinesNucleic acidsFigure3BioytheticndproductomedfromxaloacetatThendproductsthreonineandpyrimidinesserveas intermediatesin thesynthesis of additional compoundsIntermediatesFocal metaboliteEnd productsLysinea-KetoglutarateGlutamineGlutamate→Glutamic semialdehydeArginineProlineFigure6-4. Biosynthetic end productsformed from a-ketoglutarateSHIHEZI UNIVERSITY

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