Difference between revisions of "Part:BBa K4895004"

Latest revision as of 00:23, 12 October 2023

Complete Aerobic Beta-Oxidative enzymes for Unsaturated Fatty Acids in Salmonella Enterica LT2 Strai

This part represents a comprhensive, polyhistronic expression of the Salmonella Beta-Oxidation genes. The part should be used with a constitutive promoter upstream of fadB, as well as a constitutive terminator downstream of fadE/yafH.

Enzyme Activity/Pathway (specific information)

Fatty acids outside of e.coli are first recognized by fadL, with a low-affinity binding site formed by two extracellular loops. Then, the LCFA diffuses to the higher affinity binding site. The movement of the LCFA displaces the plug that is in fadL, which allows the channel to open and release the LCFA into the outer membrane. The movement from the outer memberane to the inner membrane across the periplasm is unknown as of now, but it certainly crosses into the inner membrane. After entering the inner membrane, the LCFA is then activated by a vectorial thioesterification by fadD. fadD, the essential fatty acyl-coA synthetase, is then activated by ATP to couple the import of the LCFA by adding a coenzyme A molecule. This movement is energetically costly, and is a 2-step reaction.

After the FA has been activated, the Beta-Oxidation cycle involves four enzymatic steps: acyl-CoA dehydrogenase, 2-enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and 3-ketoacyl-CoA thiolase. At each cycle, the acyl-CoA is shortened by two carbons, and releases an acetyl-CoA. This degradation proceeds until the formation of an acetoacetyl-CoA, which is catalyzed by AtoB. At each turn of the Beta-Oxidation cycle, one FADH2 and one NADH is produced by the acyl-CoA dehygrogenating step and the 3-hydroxyacyl-CoA step, respectively.

Sequence and Features