scholarly journals The Structure of (3R)-Hydroxyacyl-Acyl Carrier Protein Dehydratase (FabZ) fromPseudomonas aeruginosa

2004 ◽  
Vol 279 (50) ◽  
pp. 52593-52602 ◽  
Author(s):  
Matthew S. Kimber ◽  
Fernando Martin ◽  
Yingjie Lu ◽  
Simon Houston ◽  
Masoud Vedadi ◽  
...  

Type II fatty acid biosynthesis systems are essential for membrane formation in bacteria, making the constituent proteins of this pathway attractive targets for antibacterial drug discovery. The third step in the elongation cycle of the type II fatty acid biosynthesis is catalyzed by β-hydroxyacyl-(acyl carrier protein) (ACP) dehydratase. There are two isoforms. FabZ, which catalyzes the dehydration of (3R)-hydroxyacyl-ACP totrans-2-acyl-ACP, is a universally expressed component of the bacterial type II system. FabA, the second isoform, as has more limited distribution in nature and, in addition to dehydration, also carries out the isomerization oftrans-2- tocis-3-decenoyl-ACP as an essential step in unsaturated fatty acid biosynthesis. We report the structure of FabZ from the important human pathogenPseudomonas aeruginosaat 2.5 Å of resolution.PaFabZ is a hexamer (trimer of dimers) with the His/Glu catalytic dyad located within a deep, narrow tunnel formed at the dimer interface. Site-directed mutagenesis experiments showed that the obvious differences in the active site residues that distinguish the FabA and FabZ subfamilies of dehydratases do not account for the unique ability of FabA to catalyze isomerization. Because the catalytic machinery of the two enzymes is practically indistinguishable, the structural differences observed in the shape of the substrate binding channels of FabA and FabZ lead us to hypothesize that the different shapes of the tunnels control the conformation and positioning of the bound substrate, allowing FabA, but not FabZ, to catalyze the isomerization reaction.

2004 ◽  
Vol 48 (5) ◽  
pp. 1541-1547 ◽  
Author(s):  
Losee L. Ling ◽  
Jun Xian ◽  
Syed Ali ◽  
Bolin Geng ◽  
Jun Fan ◽  
...  

ABSTRACT Bacterial enoyl-acyl carrier protein reductase (ENR) catalyzes an essential step in fatty acid biosynthesis. ENR is an attractive target for narrow-spectrum antibacterial drug discovery because of its essential role in metabolism and its sequence conservation across many bacterial species. In addition, the bacterial ENR sequence and structural organization are distinctly different from those of mammalian fatty acid biosynthesis enzymes. High-throughput screening to identify inhibitors of Escherichia coli ENR yielded four structurally distinct classes of hits. Several members of one of these, the 2-(alkylthio)-4,6-diphenylpyridine-3-carbonitriles (“thiopyridines”), inhibited both purified ENR (50% inhibitory concentration [IC50] = 3 to 25 μM) and the growth of Staphylococcus aureus and Bacillus subtilis (MIC = 1 to 64 μg/ml). The effect on cell growth is due in part to inhibition of fatty acid biosynthesis as judged by inhibition of incorporation of [14C]acetate into fatty acids and by the increased sensitivity of cells that underexpress an ENR-encoding gene (four- to eightfold MIC shift). Synthesis of a variety of compounds in this chemical series revealed a correlation between IC50 and MIC, and the results provided initial structure-activity relationships. Preliminary structure-activity relationships, potency on purified ENR, and activity on bacterial cells indicate that members of the thiopyridine chemical series are effective fatty acid biosynthesis inhibitors suitable for further antibacterial development.


2020 ◽  
Author(s):  
Jeffrey T. Mindrebo ◽  
Laetitia E. Misson ◽  
Caitlin Johnson ◽  
Joseph P. Noel ◽  
Michael D. Burkart

ABSTRACTElongating ketosynthases (KSs) catalyze carbon-carbon bond forming reactions during the committed step for each round of chain extension in both fatty acid synthases (FASs) and polyketide synthases (PKSs). A small α-helical acyl carrier protein (ACP) shuttles fatty acyl intermediates between enzyme active sites. To accomplish this task, ACP relies on a series of dynamic interactions with multiple partner enzymes of FAS and associated FAS-dependent pathways. Recent structures of the Escherichia coli FAS ACP, AcpP, in covalent complexes with its two cognate elongating KSs, FabF and FabB, provide high-resolution detail of these interfaces, but a systematic analysis of specific interfacial interactions responsible for stabilizing these complexes has not yet been undertaken. Here, we use site-directed mutagenesis with both in vitro and in vivo activity analyses to quantitatively evaluate these contacting surfaces between AcpP and FabF. We delineate the FabF interface into three interacting regions and demonstrate the effects of point mutants, double mutants, and region delete variants. Results from these analyses reveal a robust and modular FabF interface capable of tolerating seemingly critical interface mutations with only the deletion of entire regions significantly compromising activity. Structure and sequence analysis of FabF orthologs from related type II FAS pathways indicate significant conservation of type II FAS KS interface residues and, overall, support its delineation into interaction regions. These findings strengthen our mechanistic understanding of molecular recognition events between ACPs and FAS enzymes and provide a blueprint for engineering ACP-dependent biosynthetic pathways.


2007 ◽  
Vol 14 (7) ◽  
pp. 775-783 ◽  
Author(s):  
Ashish Misra ◽  
Shailendra Kumar Sharma ◽  
Namita Surolia ◽  
Avadhesha Surolia

Planta ◽  
2010 ◽  
Vol 231 (6) ◽  
pp. 1277-1289 ◽  
Author(s):  
Damián González-Mellado ◽  
Penny von Wettstein-Knowles ◽  
Rafael Garcés ◽  
Enrique Martínez-Force

2010 ◽  
Vol 17 (7) ◽  
pp. 776-785 ◽  
Author(s):  
Eliza Płoskoń ◽  
Christopher J. Arthur ◽  
Amelia L.P. Kanari ◽  
Pakorn Wattana-amorn ◽  
Christopher Williams ◽  
...  

2000 ◽  
Vol 182 (2) ◽  
pp. 365-370 ◽  
Author(s):  
Keum-Hwa Choi ◽  
Richard J. Heath ◽  
Charles O. Rock

ABSTRACT A universal set of genes encodes the components of the dissociated, type II, fatty acid synthase system that is responsible for producing the multitude of fatty acid structures found in bacterial membranes. We examined the biochemical basis for the production of branched-chain fatty acids by gram-positive bacteria. Two genes that were predicted to encode homologs of the β-ketoacyl-acyl carrier protein synthase III of Escherichia coli (eFabH) were identified in theBacillus subtilis genome. Their protein products were expressed, purified, and biochemically characterized. Both B. subtilis FabH homologs, bFabH1 and bFabH2, carried out the initial condensation reaction of fatty acid biosynthesis with acetyl-coenzyme A (acetyl-CoA) as a primer, although they possessed lower specific activities than eFabH. bFabH1 and bFabH2 also utilized iso- and anteiso-branched-chain acyl-CoA primers as substrates. eFabH was not able to accept these CoA thioesters. Reconstitution of a complete round of fatty acid synthesis in vitro with purified E. coli proteins showed that eFabH was the only E. colienzyme incapable of using branched-chain substrates. Expression of either bFabH1 or bFabH2 in E. coli resulted in the appearance of a branched-chain 17-carbon fatty acid. Thus, the substrate specificity of FabH is an important determinant of branched-chain fatty acid production.


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