Recombinant Salmonella schwarzengrund Glycerol-3-phosphate acyltransferase (plsY)

What is the enzymatic function of Glycerol-3-phosphate acyltransferase (plsY) in Salmonella schwarzengrund?

Glycerol-3-phosphate acyltransferase (plsY) in Salmonella schwarzengrund functions as a critical enzyme in phospholipid biosynthesis, catalyzing the acylation of glycerol-3-phosphate (G3P) to form lysophosphatidic acid (LPA) - the first committed step in membrane phospholipid synthesis. This acyltransferase has EC classifications 2.3.1.15 and 2.3.1.n5, confirming its role in transferring acyl groups to glycerol-3-phosphate . The enzyme is also known as LPA synthase, highlighting its role in generating the lysophosphatidic acid intermediate in the phospholipid biosynthetic pathway . The enzymatic activity is essential for bacterial membrane biogenesis, making it crucial for cellular integrity and potentially playing a role in pathogenesis.

What is the protein structure and sequence information for Salmonella schwarzengrund plsY?

The Salmonella schwarzengrund plsY protein (UniProt ID: B4TVU1) consists of 205 amino acids with a comprehensive sequence of: MSAIAPGMILFAYLCGSISSAILVCRIAGLPDPRESGSGNPGATNVLRIGGKGAAVAVLIFDI LKGmLPVWGAYALGVTPFWLGLIAIAACLGHIWPVFFGFKGGKGVATAFGAIAPIGWDLTGV MAGTWLLTVLLSGYSSLGAIVSALIAPFYVWWFKPQFTFPVSmLSCLILLRHHDNIQRLWRRQ ETKIWTKLKKKRQKDSE . The protein is predominantly membrane-associated with multiple transmembrane regions, as evidenced by the hydrophobic amino acid clusters in its sequence. The ordered locus name for the gene in the Salmonella schwarzengrund genome is SeSA_A3397, and it has the synonym ygiH . Understanding this protein structure is essential for investigating membrane topology and functional domains that contribute to catalytic activity.

How does plsY differ from the alternative glycerol-3-phosphate acyltransferase (plsB) pathway?

While both plsY and plsB catalyze the acylation of glycerol-3-phosphate, they represent distinct evolutionary pathways for phospholipid synthesis. The plsY pathway (found in Salmonella schwarzengrund) utilizes acyl-ACP (acyl carrier protein) as the acyl donor and represents a more widely distributed pathway among bacteria. In methodological terms, researchers investigating comparative biochemistry should use distinct acyl donor substrates when assaying these enzymes: acyl-phosphate donors for plsY versus acyl-CoA substrates for plsB systems. When designing inhibitor studies or metabolic flux analyses, this fundamental difference in substrate preference must be accounted for in experimental design.

What are the optimal storage conditions for recombinant Salmonella schwarzengrund plsY?

Recombinant Salmonella schwarzengrund plsY should be stored in a Tris-based buffer containing 50% glycerol, specifically optimized for this protein's stability . For short-term storage (up to one week), the protein can be maintained at 4°C in working aliquots . For extended preservation, store at -20°C, or preferably at -80°C for maximum stability and activity retention over extended periods . Notably, repeated freeze-thaw cycles should be strictly avoided as they significantly compromise protein integrity and enzymatic activity . A methodological approach to minimize freeze-thaw damage involves preparing single-use aliquots upon initial thawing. Researchers should validate protein activity after storage periods using standard acyltransferase assays to ensure experimental reproducibility.

What conjugation methods can be used when studying plsY-containing plasmids in Salmonella schwarzengrund?

When studying plasmids containing genes like plsY in Salmonella schwarzengrund, researchers can employ two effective conjugation approaches. The plate mating method involves cross-streaking the donor (Salmonella strain) and recipient (such as E. coli J53) on LB agar plates, incubating for 24 hours, then collecting cells from the intersection and streaking them onto selective media containing appropriate antibiotics . Alternatively, if plate mating proves unsuccessful, researchers can use broth mating by growing donor and recipient strains separately in LB broth overnight, mixing them in a 1:1 ratio, centrifuging at 7,000 × g for 5 minutes, then resuspending the pellet in 250 μL LB broth and spotting onto LB agar for 3-4 hours before selection . PCR confirmation of plasmid transfer should follow using primers specific to the target gene or plasmid markers.

How can researchers verify plsY enzymatic activity in recombinant preparations?

To verify enzymatic activity of recombinant plsY, researchers should implement a radiometric assay measuring the incorporation of radiolabeled acyl substrates into lysophosphatidic acid. The methodology involves incubating purified recombinant plsY with glycerol-3-phosphate and radiolabeled acyl-ACP or acyl-phosphate donors in an appropriate buffer system (typically containing divalent cations like Mg²⁺), followed by lipid extraction and thin-layer chromatography separation. Quantification of radiolabeled lysophosphatidic acid formation provides direct evidence of enzymatic activity. Alternative non-radiometric approaches include coupled enzyme assays that monitor inorganic phosphate release or HPLC-based methods tracking substrate depletion and product formation. Activity measurements should include proper controls—heat-inactivated enzyme and reaction mixtures lacking individual substrates—to validate specificity.

How does plsY contribute to Salmonella schwarzengrund virulence mechanisms?

The contribution of plsY to Salmonella schwarzengrund virulence involves its essential role in phospholipid biosynthesis, which affects membrane composition and cellular adaptation during host infection. While the search results don't specifically address plsY's role in virulence, related research on Salmonella schwarzengrund indicates that membrane-associated proteins and lipid metabolism play crucial roles in bacterial invasion and persistence in human epithelial cells . Methodologically, researchers investigating plsY's virulence contributions should employ invasion assays with human intestinal epithelial cells (such as Caco-2 cells) using wild-type strains and plsY mutants or modified expression strains. This approach involves infecting epithelial cells at a multiplicity of infection (MOI) of 10, followed by gentamicin treatment (200 μg/mL) to eliminate extracellular bacteria, cell lysis with chilled Triton X-100 (0.1%), and CFU determination on appropriate media .

How can researchers investigate plsY expression under different environmental conditions?

To investigate plsY expression under various environmental conditions, researchers should employ quantitative reverse transcription PCR (qRT-PCR) to measure transcript levels in Salmonella schwarzengrund exposed to different stimuli. The methodology involves extracting total RNA from bacterial cultures grown under test conditions (varying pH, temperature, nutrient limitation, host-mimicking environments), followed by cDNA synthesis and qPCR amplification using plsY-specific primers. Expression should be normalized to stable reference genes validated for consistent expression under the tested conditions. Complementary approaches include reporter gene fusions (plsY promoter driving luciferase or fluorescent protein expression) for real-time monitoring of transcriptional activity, and proteomics analysis for quantifying plsY protein levels using techniques such as western blotting or mass spectrometry.

What methodologies are appropriate for studying plsY in context of antimicrobial resistance?

Studying plsY in the context of antimicrobial resistance requires multi-faceted methodological approaches. Researchers should implement minimum inhibitory concentration (MIC) determination for various antibiotics using wild-type and plsY-modified strains (overexpression, knockdown, or site-directed mutants) to identify correlations between plsY activity and resistance profiles. Membrane permeability assays using fluorescent dyes like SYTOX Green can evaluate how alterations in plsY activity affect membrane integrity and antibiotic penetration. Lipid profiling through mass spectrometry techniques should be employed to characterize alterations in membrane composition that might contribute to resistance. Additionally, researchers should conduct synergy testing between plsY inhibitors and conventional antibiotics using checkerboard assays to identify potential combination therapies that overcome resistance mechanisms associated with membrane lipid composition.

How does Salmonella schwarzengrund plsY compare to homologs in other bacterial species?

Comparative analysis of Salmonella schwarzengrund plsY with homologs in other bacterial species reveals important evolutionary and functional relationships. The protein shows significant sequence conservation among Enterobacteriaceae, particularly within the catalytic domains. Methodologically, researchers should perform multiple sequence alignments using tools like MUSCLE or CLUSTAL, followed by calculation of sequence identity/similarity percentages and identification of conserved motifs. Phylogenetic tree construction using maximum likelihood or Bayesian methods will establish evolutionary relationships. Structural homology modeling using solved crystal structures of plsY homologs can identify conserved structural elements versus species-specific features. These comparative analyses provide insights into substrate specificity determinants and potential species-specific functional adaptations.

What insights can be gained from studying plsY in the context of Salmonella schwarzengrund phylogeny?

Studying plsY in the context of Salmonella schwarzengrund phylogeny can provide valuable insights into strain evolution and adaptation. SNP-based phylogenetic analysis of Salmonella schwarzengrund isolates reveals distinct lineages that may contain variations in metabolic genes like plsY . Researchers should employ whole genome sequencing followed by comparative genomic analysis to identify plsY sequence variations across isolates from different sources (food vs. clinical) and geographical regions. Methodologically, this involves extracting genomic DNA using kits like DNeasy Blood and Tissue kit, library preparation (e.g., using Nextera XT), sequencing on platforms like Illumina MiSeq with 2 × 250 pair-end chemistry, and subsequent bioinformatic analysis . The CFSAN SNP Pipeline can be used to identify single nucleotide polymorphisms, followed by phylogenetic tree construction using tools like FastTree with the general time reversible model and bootstrap analysis .

How do virulence factors in Salmonella schwarzengrund interact with phospholipid biosynthesis pathways?

The interaction between virulence factors and phospholipid biosynthesis pathways in Salmonella schwarzengrund represents a complex relationship affecting bacterial pathogenicity. While the specific interactions between plsY and virulence factors are not detailed in the search results, research on Salmonella schwarzengrund shows that isolates often carry similar virulence gene profiles alongside plasmids that may influence metabolic pathways . Methodologically, researchers should employ transcriptomic approaches (RNA-seq) to identify co-expression patterns between plsY and virulence genes under infection-relevant conditions. Protein-protein interaction studies using bacterial two-hybrid systems or co-immunoprecipitation can identify direct interactions between plsY and virulence-associated proteins. Metabolic flux analysis using stable isotope-labeled precursors can determine how virulence factor expression alters phospholipid metabolism. These approaches collectively provide a systems-level understanding of how membrane biogenesis interfaces with virulence mechanisms.

How can CRISPR-Cas9 technology be applied to study plsY function in Salmonella schwarzengrund?

CRISPR-Cas9 technology offers powerful approaches for investigating plsY function in Salmonella schwarzengrund. Researchers should design sgRNAs targeting the plsY gene (SeSA_A3397) with careful consideration of PAM sites and off-target effects. For complete gene knockout, the methodology involves introducing the CRISPR-Cas9 system via transformation with a plasmid containing both Cas9 and the sgRNA, alongside a repair template with homology arms flanking the target region. For point mutations to study specific residues in the catalytic domain, researchers should design repair templates carrying the desired mutations plus silent mutations that disrupt the PAM site to prevent re-cutting. Inducible CRISPR interference (CRISPRi) using catalytically dead Cas9 (dCas9) fused to transcriptional repressors provides an alternative for studying essential genes like plsY by enabling controlled downregulation rather than complete knockout.

What high-throughput screening methods can identify inhibitors of Salmonella schwarzengrund plsY?

High-throughput screening for Salmonella schwarzengrund plsY inhibitors requires robust, scalable methodologies. Researchers should implement fluorescence-based assays in 384-well plate format where plsY activity is coupled to fluorescent reporters—either through pH-sensitive probes detecting released phosphate or through fluorescently labeled substrate analogs showing spectral shifts upon conversion. Alternately, a bioluminescence-coupled assay monitoring ATP consumption/production associated with the acyltransferase reaction provides another detection method. For cell-based screens, reporter strains with plsY expression linked to fluorescent proteins can identify compounds affecting expression, while growth inhibition assays with wild-type versus plsY-overexpressing strains can identify compounds specifically targeting plsY. Computational approaches including structure-based virtual screening should complement experimental methods, using homology models of Salmonella schwarzengrund plsY to predict binding modes of potential inhibitors before experimental validation.