scholarly journals Crystal structures and kinetic properties of enoyl-acyl carrier protein reductase I fromCandidatus Liberibacter asiaticus

2014 ◽  
Vol 23 (4) ◽  
pp. 366-377 ◽  
Author(s):  
Ling Jiang ◽  
Zengqiang Gao ◽  
Yanhua Li ◽  
Shennan Wang ◽  
Yuhui Dong
Keyword(s):  
Crystal Structures ◽  
Acyl Carrier Protein ◽  
Kinetic Properties ◽  
Carrier Protein ◽  
Liberibacter Asiaticus

scholarly journals Kinetic, inhibition and structural studies on 3-oxoacyl-ACP reductase from Plasmodium falciparum, a key enzyme in fatty acid biosynthesis

2005 ◽  
Vol 393 (2) ◽  
pp. 447-457 ◽  
Author(s):  
Sasala R. Wickramasinghe ◽  
Kirstine A. Inglis ◽  
Jonathan E. Urch ◽  
Sylke Müller ◽  
Daan M. F. van Aalten ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Plasmodium Falciparum ◽  
Fatty Acid ◽  
Fatty Acid Biosynthesis ◽  
Competitive Inhibition ◽  
Acyl Carrier Protein ◽  
Antimalarial Activity ◽  
Kinetic Properties ◽  
Carrier Protein ◽  
Acid Biosynthesis

Type II fatty acid biosynthesis represents an attractive target for the discovery of new antimalarial drugs. Previous studies have identified malarial ENR (enoyl acyl-carrier-protein reductase, or FabI) as the target for the antiseptic triclosan. In the present paper, we report the biochemical properties and 1.5 Å (1 Å=0.1 nm) crystal structure of OAR (3-oxoacyl acyl-carrier-protein reductase, or FabG), the second reductive step in fatty acid biosynthesis and its inhibition by hexachlorophene. Under optimal conditions of pH and ionic strength, Plasmodium falciparum OAR displays kinetic properties similar to those of OAR from bacteria or plants. Activity with NADH is <3% of that with NADPH. Fluorescence enhancement studies indicate that NADPH can bind to the free enzyme, consistent with kinetic and product inhibition studies suggesting a steady-state ordered mechanism. The crystal structure reveals a tetramer with a sulphate ion bound in the cofactor-binding site such that the side chains of the catalytic triad of serine, tyrosine and lysine are aligned in an active conformation, as previously observed in the Escherichia coli OAR–NADP+ complex. A cluster of positively charged residues is positioned at the entrance to the active site, consistent with the proposed recognition site for the physiological substrate (3-oxoacyl-acyl-carrier protein) in E. coli OAR. The antibacterial and anthelminthic agent hexachlorophene is a potent inhibitor of OAR (IC50 2.05 μM) displaying non-linear competitive inhibition with respect to NADPH. Hexachlorophene (EC50 6.2 μM) and analogues such as bithionol also have antimalarial activity in vitro, suggesting they might be useful leads for further development.

Structural rearrangements occurring upon cofactor binding in the Mycobacterium smegmatis β-ketoacyl-acyl carrier protein reductase MabA

2018 ◽  
Vol 74 (5) ◽  
pp. 383-393 ◽  
Author(s):  
Tanja Küssau ◽  
Marion Flipo ◽  
Niel Van Wyk ◽  
Albertus Viljoen ◽  
Vincent Olieric ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Crystal Structures ◽  
Active Site ◽  
Mycobacterium Smegmatis ◽  
Fatty Acid Synthase ◽  
Fatty Acid Biosynthesis ◽  
Acyl Carrier Protein ◽  
Rational Drug Design ◽  
Carrier Protein ◽  
Cofactor Binding

In mycobacteria, the ketoacyl-acyl carrier protein (ACP) reductase MabA (designated FabG in other bacteria) catalyzes the NADPH-dependent reduction of β-ketoacyl-ACP substrates to β-hydroxyacyl-ACP products. This first reductive step in the fatty-acid biosynthesis elongation cycle is essential for bacteria, which makes MabA/FabG an interesting drug target. To date, however, very few molecules targeting FabG have been discovered and MabA remains the only enzyme of the mycobacterial type II fatty-acid synthase that lacks specific inhibitors. Despite the existence of several MabA/FabG crystal structures, the structural rearrangement that occurs upon cofactor binding is still not fully understood. Therefore, unlocking this knowledge gap could help in the design of new inhibitors. Here, high-resolution crystal structures of MabA from Mycobacterium smegmatis in its apo, NADP+-bound and NADPH-bound forms are reported. Comparison of these crystal structures reveals the structural reorganization of the lid region covering the active site of the enzyme. The crystal structure of the apo form revealed numerous residues that trigger steric hindrance to the binding of NADPH and substrate. Upon NADPH binding, these residues are pushed away from the active site, allowing the enzyme to adopt an open conformation. The transition from an NADPH-bound to an NADP+-bound form is likely to facilitate release of the product. These results may be useful for subsequent rational drug design and/or for in silico drug-screening approaches targeting MabA/FabG.

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