3-Hydroxyacyl-ACP: CoA transferase

Figure 7,7 Common metabolic pathways that are involved in the biosynthesis of PHA in microorganisms. PhaA P-ketothiolase PhaB NAOH-dependent acetoacetyl-CoA reductase PhaC PHA synthase PhaG 3-hydroxyacyl-ACP CoA transferase PhaJ (R)-enoyl-CoA hydratase FabC malonyl-CoA ACP transcylase FabG 3-Ketoacyl-CoA reductase...

Pathway III involves 3-hydroxyacyI-ACP-CoA transferase (PhaG) and malonyl-CoA-ACP transacylase (FabD), which help supply 3-hydroxyacyl-ACP to form PHA monomer 3-hydroxyacyI-CoA, leading to PHA formation under the action of PHA synthase (Sudesh et al. 2000 Zheng et al. 2005 Taguchi et al. 1999). 

Spatially, the enzyme activities are arranged into three different domains. Domain 1 catalyzes the entry of the substrates acetyl CoA and malonyl CoA by [ACPj-S-acetyltransferase [1] and [ACPJ-Smalonyl transferase [2] and subsequent condensation of the two partners by 3-oxoacyl-[ACP] synthase [3]. Domain 2 catalyzes the conversion of the 3-0X0 group to a CH2 group by 3-oxoacyl-[ACP]-reductase [4], 3-hydroxyacyl-[ACP -dehydratase [5], and enoyl-[ACP]-re-... 

Acyl carrier protein (ACP) Acetyi-CoA-ACP transacetyiase (AT) j3-Ketoacyi-ACP synthase (KS) Malonyl-CoA-ACP transferase (MT) /3-Ketoacyl-ACP reductase (KR) /3-Hydroxyacyl-ACP dehydratase (HD) Enoyl-ACP reductase (ER)... 

De novo fatty acid biosynthesis StmcturaUy unrelated carbon sources such as glucose generate (R)-3-hydroxyacyl-CoA precursors via this metabolic route. (R)-3-hydroxyacyl-ACP is converted to (/ )-3-hydroxyacyl CoA in a reaction, which is catalysed by the enzyme (R)-3-hydroxyacyl-CoA-ACP transferase. This enzyme is encoded by the phaG gene (Sudesh et al., 2000). 

Figure 3.2 Enzyme systems associated with the de novo synthesis of fatty acids in the plastid. (a) Acetyl-CoA carboxylase (EC 6.4.1.2) (b) [acyl-carrier protein] (ACP) acetyl-transferase (EC 2.3.1.38) (c) [ACP] malonyltransferase (EC 2.3.1.39) (dl) 3-oxoacyl-[ACP] synthase I (d2) 3-oxoacyl-[ACP] synthase II (EC 2.3.1.41) (d3) 3-oxoacyl-[ACP] synthase III (e) 3-oxoacyl-[ACP] reductase (EC 1.1.1.100) (f) 3-hydroxyacyl-[ACP] dehydratase (g) enoyl-[ACP] reductase (EC 1.3.1.9/10) (d)-(g) constitutes fatty acid synthase...

Abbreviations FASN, fatty acid synthase ACC, acetyl-CoA-carboxylase ACL, ATP-citrate lyase NADPH, nicotinamide adenine dinucleotide phosphate MAT, malonyl acetyl transferases KS, ketoacyl synthase KR, p-ketoacyl reductase DH, p-hydroxyacyl dehydratase ER, enoyl reductase TE, thioesterase ACP, acyl carrier protein VLCFA, very long chain fatty acids ELOVL, elongation of very long chain fatty acids SCDl, stearoyl-CoA desaturase-1 AMPK, AMP-activated kinase ME, malic enzyme FASKOL, liver-specific deletion of FAS PPARa, Peroxisome Proliferator-Activating Receptor alpha HMG-CoA, 3-hydroxy-3-methyl-glutaryl-CoA SREBP, sterol response element binding protein SIP, site-one protease S2P, site-two... 

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