Metabolic Diversity and Pathways

• Chemolithotrophs occurs only in prokaryotes
• Embden-Meyerhof-Parnas Pathway

  • regulated by kinases
  • transported via group translocation (G6P)
  • active transportation = phosphorylation by hexokinase
  • G6P may also be obtained from glycogen

  Phosphoglucomutase: converts G1P to G6P (reversible)
• Modified Glycolytic Pathways

  1. Methylglyoxal Bypass
  2. Ketogluconate Pathway/Entner-Doudoroff Pathway
  3. Pentose Phosphate Pathway/Phosphogluconate Pathway/Hexose Monophosphate shunt
  4. Phosphoketolase Pathway
• Methylyglyoxal Bypass


  utilized by E. coli and P. saccharophila under phosphorus limited conditions

  • Methylglyoxal regulate the oxidation of DHAP into pyruvate
  • reduced derivative of pyruvic acid
  • toxic, highly reactive; destroys NA and CHON by reacting with guanine, adenine, arg, lys, cys
  • accumulation triggers synthesis of membrane proteins and glyoxalase
  • Methylglyoxal synthaseL regulated by Pi through feedback inhibition and activated by DHAP
• Entner-Doudoroff Pathway/Ketogluconate Pathway

  • active in E. coli and other gram-negative; present in some archaebacteria
  • sole pathway for Z. mobilis (anaerobic, obligate fermentative)
  • eda facilitates conversion of KDPG into ethanol
  • edd converts 6-phosphogluconate into KDPG
• Synthesis of Peptidoglycan in Bacteria

  • UDP: necessary for other carbohydrates to attach
  • Ddl: condenses 2 D-Ala
  • Bactoprenol: knocks of UMP to link MurNAc-Glyc to 5 amino acids
  • MurG: establishes NAM-NAG bond
  • FtsW and MurJ: flips the entire process to the periplasm
  • Transglycosylation: elongation of NAM-NAG
  • Transpeptidation: cross-linking of peptidoglycan chains
  • Carboxypeptidation: loses terminal D-ala for carboxyl group to attach