The puzzle of two tandem acyl-CoA ligases of F1.

Unlabelled: The F1 genome and those of many other pseudomonads contain two tandem genes encoding acyl-CoA ligases Pput_1340 () and Pput_1339 () with Pput_1339 () being the upstream gene. The designation was assigned when both genes were found to complement the growth of an acyl-CoA synthetase deletion strain with oleic acid as sole carbon source. Site-directed mutagenesis showed that residues of the ATP/AMP domain required for function of FadD were also essential for full function of FadD1 and FadD2.

The Enteric Bacterium Enterococcus faecalis Elongates and Incorporates Exogenous Short and Medium Chain Fatty Acids Into Membrane Lipids.

Enterococcus faecalis incorporates and elongates exogeneous short- and medium-chain fatty acids to chains sufficiently long to enter membrane phospholipid synthesis. The acids are activated by the E. faecalis fatty acid kinase (FakAB) system and converted to acyl-ACP species that can enter the fatty acid synthesis cycle to become elongated.

Lipoic acid attachment to proteins: stimulating new developments.

SUMMARYLipoic acid-modified proteins are essential for central metabolism and pathogenesis. In recent years, the and lipoyl assembly pathways have been modified and extended to archaea and diverse eukaryotes including humans. These extensions include a new pathway to insert the key sulfur atoms of lipoate, several new pathways of lipoate salvage, and a novel use of lipoic acid in sulfur-oxidizing bacteria.

Diversity in fatty acid elongation enzymes: The FabB long-chain β-ketoacyl-ACP synthase I initiates fatty acid synthesis in Pseudomonas putida F1.

The condensation of acetyl-CoA with malonyl-acyl carrier protein (ACP) by β-ketoacyl-ACP synthase III (KAS III, FabH) and decarboxylation of malonyl-ACP by malonyl-ACP decarboxylase are the two pathways that initiate bacterial fatty acid synthesis (FAS) in Escherichia coli. In addition to these two routes, we report that Pseudomonas putida F1 β-ketoacyl-ACP synthase I (FabB), in addition to playing a key role in fatty acid elongation, also initiates FAS in vivo. We report that although two P.

Bacterial Emission Factors: A Foundation for the Terrestrial-Atmospheric Modeling of Bacteria Aerosolized by Wildland Fires.

Wildland fire is a major global driver in the exchange of aerosols between terrestrial environments and the atmosphere. This exchange is commonly quantified using emission factors or the mass of a pollutant emitted per mass of fuel burned. However, emission factors for microbes aerosolized by fire have yet to be determined.

Biotin protein ligase as you like it: Either extraordinarily specific or promiscuous protein biotinylation.

Biotin (vitamin H or B7) is a coenzyme essential for all forms of life. Biotin has biological activity only when covalently attached to a few key metabolic enzyme proteins. Most organisms have only one attachment enzyme, biotin protein ligase (BPL), which attaches biotin to all target proteins.

Suppressor mutants demonstrate the metabolic plasticity of unsaturated fatty acid synthesis in PAO1.

PAO1 has two aerobic pathways for synthesis of unsaturated fatty acids (UFAs), DesA and DesB plus the oxygen independent FabAB pathway. The DesA desaturase acts on saturated acyl chains of membrane phospholipid bilayers whereas the substrates of the DesB desaturase are thought to be long chain saturated acyl-CoA thioesters derived from exogeneous saturated fatty acids that are required to support DesB-dependent growth. Under suitable aerobic conditions either of these membrane-bound desaturates can support growth of strains lacking the oxygen independent FabAB pathway.

Two neglected but valuable genetic tools for Escherichia coli and other bacteria: In vivo cosmid packaging and inducible plasmid replication.

In physiology and synthetic biology, it can be advantageous to introduce a gene into a naive bacterial host under conditions in which all cells receive the gene and remain fully functional. This cannot be done by the usual chemical transformation and electroporation methods due to low efficiency and cell death, respectively. However, in vivo packaging of plasmids (called cosmids) that contain the 223 bp cos site of phage λ results in phage particles that contain concatemers of the cosmid that can be transduced into all cells of a culture.

Unsaturated fatty acid synthesis in bacteria: Mechanisms and regulation of canonical and remarkably noncanonical pathways.

Unsaturated phospholipid acyl chains are required for membrane function in most bacteria. The double bonds of the cis monoenoic chains arise by two distinct pathways depending on whether oxygen is required. The oxygen-independent pathway (traditionally called the anaerobic pathway) introduces the cis double bond by isomerization of the trans double bond intermediate of the fatty acid elongation cycle.

The acyl carrier proteins of lipid synthesis are busy having other affairs.

This is a review of the acyl carrier proteins (ACPs) of type II fatty acid synthesis in bacteria and mitochondria, their structures and protein interactions. Type II fatty acid synthesis in bacteria (Prog. Lipid Res.

Growth of ∆ strains is restored by increased saturated fatty acid synthesis.

The acyl-acyl carrier protein (ACP) phosphate acyltransferase PlsX plays an important role in phospholipid synthesis and exogenous fatty acid incorporation. Loss of almost completely blocks growth by decreasing phospholipid synthesis, which leads to abnormally long-chain acyl chains in the cell membrane phospholipids. The ∆ strain failed to grow without supplementation with an appropriate exogenous fatty acid.

How an overlooked gene in coenzyme a synthesis solved an enzyme mechanism predicament.

Coenzyme A (CoA) is an essential cofactor throughout biology. The first committed step in the CoA synthetic pathway is synthesis of β-alanine from aspartate. In Escherichia coli and Salmonella enterica panD encodes the responsible enzyme, aspartate-1-decarboxylase, as a proenzyme.

Divergent unsaturated fatty acid synthesis in two highly related model pseudomonads.

The genomes of the best-studied pseudomonads, Pseudomonas aeruginosa and Pseudomonas putida, which share 85% of the predicted coding regions, contain a fabA fabB operon (demonstrated in P. aeruginosa, putative in P. putida).

Unsaturated fatty acid synthesis in Enterococcus faecalis requires a specific enoyl-ACP reductase.

The Enterococcus faecalis genome contains two enoyl-ACP reductases genes, fabK and fabI, which encode proteins having very different structures. Enoyl-ACP reductase catalyzes the last step of the elongation cycle of type II fatty acid synthesis pathway. The fabK gene is located within the large fatty acid synthesis operon whereas fabI is located together with two genes fabN and fabO required for unsaturated fatty acid synthesis.

The Impact of Emerging Technologies on Residency Selection by Medical Students in 2017 and 2021, With a Focus on Diagnostic Radiology.

Rationale And Objectives: We sought to determine the perceived impact of artificial intelligence (AI) and other emerging technologies (ET) on various specialties by medical students in both 2017 and 2021 and how this might affect their residency selections.

Materials And Methods: We conducted a brief, anonymous survey of all medical students at a single institution in 2017 and 2021. Survey questions evaluated (1) incentives motivating residency selection and career path, (2) degree of interest in each specialty, (3) perceived effect that ET will have on job prospects for each specialty, and (4) those specialties that students would not consider because of concerns regarding ET.

The Two Acyl Carrier Proteins of Enterococcus faecalis Have Nonredundant Functions.

Enterococcus faecalis encodes two proteins, AcpA and AcpB, having the characteristics of acyl carrier proteins (ACPs). We report that the gene located in the fatty acid synthesis operon is essential for fatty acid synthesis and the Δ strain requires unsaturated fatty acids for growth. The Δ strain could be complemented by a plasmid carrying a wild-type gene, but not by a plasmid carrying a wild-type gene.

Loss of β-Ketoacyl Acyl Carrier Protein Synthase III Activity Restores Multidrug-Resistant Escherichia coli Sensitivity to Previously Ineffective Antibiotics.

Antibiotic resistance is one of the most prominent threats to modern medicine. In the latest World Health Organization list of bacterial pathogens that urgently require new antibiotics, 9 out of 12 are Gram-negative, with four being of "critical priority." One crucial barrier restricting antibiotic efficacy against Gram-negative bacteria is their unique cell envelope.

The FabT Transcription Factor Regulates Fatty Acid Biosynthesis in Response to Exogeneous Fatty Acids.

The phospholipid acyl chains of can be derived either by synthesis or by incorporation of exogenous fatty acids through the fatty acid kinase complex (Fak)-phosphate acyltransferase (PlsX) pathway. Exogenous fatty acids suppress fatty acid synthesis through the transcriptional repressor FabT, the loss of which eliminated regulation of fatty acid biosynthesis and resulted in decreased incorporation of exogenous unsaturated fatty acids. Purified FabT bound to the promoters of several fatty acid synthesis genes that contain a specific palindromic sequence and binding was enhanced by acylated derivatives of acyl carrier protein B (acyl-AcpB).

Advances in the Structural Biology, Mechanism, and Physiology of Cyclopropane Fatty Acid Modifications of Bacterial Membranes.

Cyclopropane fatty acid (CFA) synthase catalyzes a remarkable reaction. The double bonds of unsaturated fatty acyl chains of phospholipid bilayers are converted to cyclopropane rings by transfer of a methylene moiety from S-adenosyl-L-methionine (SAM). The substrates of this modification are functioning membrane bilayer phospholipids.

Helicobacter pylori FabX contains a [4Fe-4S] cluster essential for unsaturated fatty acid synthesis.

Unsaturated fatty acids (UFAs) are essential for functional membrane phospholipids in most bacteria. The bifunctional dehydrogenase/isomerase FabX is an essential UFA biosynthesis enzyme in the widespread human pathogen Helicobacter pylori, a bacterium etiologically related to 95% of gastric cancers. Here, we present the crystal structures of FabX alone and in complexes with an octanoyl-acyl carrier protein (ACP) substrate or with holo-ACP.

A conserved and seemingly redundant Escherichia coli biotin biosynthesis gene expressed only during anaerobic growth.

Biotin is an essential metabolic cofactor and de novo biotin biosynthetic pathways are widespread in microorganisms and plants. Biotin synthetic genes are generally found clustered into bio operons to facilitate tight regulation since biotin synthesis is a metabolically expensive process. Dethiobiotin synthetase (DTBS) catalyzes the penultimate step of biotin biosynthesis, the formation of 7,8-diaminononanoate (DAPA).

A cryptic long-chain 3-ketoacyl-ACP synthase in the Pseudomonas putida F1 unsaturated fatty acid synthesis pathway.

The Pseudomonas putida F1 genome contains five genes annotated as encoding 3-ketoacyl-acyl carrier protein (ACP) synthases. Four are annotated as encoding FabF (3-ketoacyl-ACP synthase II) proteins, and the fifth is annotated as encoding a FabB (3-ketoacyl-ACP synthase I) protein. Expression of one of the FabF proteins, FabF2, is cryptic in the native host and becomes physiologically important only when the repressor controlling fabF2 transcription is inactivated.

The Classical, Yet Controversial, First Enzyme of Lipid Synthesis: Escherichia coli Acetyl-CoA Carboxylase.

Escherichia coli acetyl-CoA carboxylase (ACC), the enzyme responsible for synthesis of malonyl-CoA, the building block of fatty acid synthesis, is the paradigm bacterial ACC. Many reports on the structures and stoichiometry of the four subunits comprising the active enzyme as well as on regulation of ACC activity and expression have appeared in the almost 20 years since this subject was last reviewed. This review seeks to update and expand on these reports.

A division of labor between two biotin protein ligase homologs.

Group I biotin protein ligases (BPLs) catalyze the covalent attachment of biotin to its cognate acceptor proteins. In contrast, Group II BPLs have an additional N-terminal DNA-binding domain and function not only in biotinylation but also in transcriptional regulation of genes of biotin biosynthesis and transport. Most bacteria contain only a single biotin protein ligase, whereas Clostridium acetobutylicum contains two biotin protein ligase homologs: BplA and BirA'.