Title: Enzymatic Characterization of a Novel HSL Family IV Esterase EstD04 from Pseudomonas sp. D01 in Mealworm Gut Microbiota Kuan JE, Tsai CH, Chou CC, Wu C, Wu WF Ref: Molecules, 28:, 2023 : PubMed
Pseudomonas sp. D01, capable of growing in tributyrin medium, was isolated from the gut microbiota of yellow mealworm. By using in silico analyses, we discovered a hypothesized esterase encoding gene in the D01 bacterium, and its encoded protein, EstD04, was classified as a bacterial hormone-sensitive lipase (bHSL) of the type IV lipase family. The study revealed that the recombinant EstD04-His(6x) protein exhibited esterase activity and broad substrate specificity, as it was capable of hydrolyzing p-nitrophenyl derivatives with different acyl chain lengths. By using the most favorable substrate p-nitrophenyl butyrate (C(4)), we defined the optimal temperature and pH value for EstD04 esterase activity as 40 degreesC and pH 8, respectively, with a catalytic efficiency (k(cat)/K(m)) of 6.17 x 10(3) mM(-1) s(-1) at 40 degreesC. EstD04 demonstrated high stability between pH 8 and 10, and thus, it might be capably used as an alkaline esterase in industrial applications. The addition of Mg(2+) and NH(4)(+), as well as DMSO, could stimulate EstD04 enzyme activity. Based on bioinformatic motif analyses and tertiary structural simulation, we determined EstD04 to be a typical bHSL protein with highly conserved motifs, including a triad catalytic center (Ser(160), Glu(253), and His(283)), two cap regions, hinge sites, and an oxyanion hole, which are important for the type IV enzyme activity. Moreover, the sequence analysis suggested that the two unique discrete cap regions of EstD04 may contribute to its alkali mesophilic nature, allowing EstD04 to exhibit extremely distinct physiological properties from its evolutionarily closest esterase.
Amyotrophic lateral sclerosis (ALS) is a synaptopathy accompanied by the presence of cytoplasmic aggregates containing TDP-43, an RNA-binding protein linked to approximately 97% of ALS cases. Using a Drosophila model of ALS, we show that TDP-43 overexpression (OE) in motor neurons results in decreased expression of the Hsc70-4 chaperone at the neuromuscular junction (NMJ). Mechanistically, mutant TDP-43 sequesters hsc70-4 mRNA and impairs its translation. Expression of the Hsc70-4 ortholog, HSPA8, is also reduced in primary motor neurons and NMJs of mice expressing mutant TDP-43. Electrophysiology, imaging, and genetic interaction experiments reveal TDP-43-dependent defects in synaptic vesicle endocytosis. These deficits can be partially restored by OE of Hsc70-4, cysteine-string protein (Csp), or dynamin. This suggests that TDP-43 toxicity results in part from impaired activity of the synaptic CSP/Hsc70 chaperone complex impacting dynamin function. Finally, Hsc70-4/HSPA8 expression is also post-transcriptionally reduced in fly and human induced pluripotent stem cell (iPSC) C9orf72 models, suggesting a common disease pathomechanism.
Title: Crystal structure of vespid phospholipase A1 reveals insights into the mechanism for cause of membrane dysfunction Hou MH, Chuang CY, Ko TP, Hu NJ, Chou CC, Shih YP, Ho CL, Wang AH Ref: Insect Biochemistry & Molecular Biology, 68:79, 2016 : PubMed
Vespid phospholipase A1 (vPLA1) from the black-bellied hornet (Vespa basalis) catalyzes the hydrolysis of emulsified phospholipids and shows potent hemolytic activity that is responsible for its lethal effect. To investigate the mechanism of vPLA1 towards its function such as hemolysis and emulsification, we isolated vPLA1 from V. basalis venom and determined its crystal structure at 2.5 A resolution. vPLA1 belongs to the alpha/beta hydrolase fold family. It contains a tightly packed beta-sheet surrounded by ten alpha-helices and a Gly-X-Ser-X-Gly motif, characteristic of a serine hydrolyase active site. A bound phospholipid was modeled into the active site adjacent to the catalytic Ser-His-Asp triad indicating that Gln95 is located at hydrogen-bonding distance from the substrate's phosphate group. Moreover, a hydrophobic surface comprised by the side chains of Phe53, Phe62, Met91, Tyr99, Leu197, Ala167 and Pro169 may serve as the acyl chain-binding site. vPLA1 shows global similarity to the N-terminal domain of human pancreatic lipase (HPL), but with some local differences. The lid domain and the beta9 loop responsible for substrate selectivity in vPLA1 are shorter than in HPL. Thus, solvent-exposed hydrophilic residues can easily accommodate the polar head groups of phospholipids, thereby accounting for the high activity level of vPLA1. Our result provides a potential explanation for the ability of vPLA1 to hydrolyze phospholipids of cell membrane.
Title: Crystallization and preliminary X-ray diffraction analysis of phospholipase A1 isolated from hornet (Vespa basalis) venom Chou CC, Hou MH Ref: Acta Crystallographica Sect F Struct Biol Cryst Commun, 64:1118, 2008 : PubMed
Phospholipase A(1) (PLA(1)) isolated from the black-bellied hornet (Vespa basalis) catalyzes the hydrolysis of emulsified phospholipids in addition to the potent haemolytic activity responsible for its lethal effect. In this study, the crystallization and preliminary crystallographic analysis of PLA(1) from hornet venom with a molecular weight of 32 kDa are reported. PLA(1) was crystallized at 277 K using PEG 4000 as precipitant and a 96.5% complete native data set was collected from a frozen crystal to 2.5 A resolution at 100 K with an overall R(merge) of 6.8%. The crystal belongs to the triclinic space group P1, with unit-cell parameters a = 57.2, b = 70.2, c = 81.6 A, alpha = 107.0, beta = 109.9, gamma = 100.9 degrees . In each asymmetric unit, three or four subunits of PLA(1) are present according to the calculation of the solvent content.
Title: Structure of XC6422 from Xanthomonas campestris at 1.6 A resolution: a small serine alpha/beta-hydrolase Yang CY, Chin KH, Chou CC, Wang AH, Chou SH Ref: Acta Crystallographica Sect F Struct Biol Cryst Commun, 62:498, 2006 : PubMed
XC6422 is a conserved hypothetical protein from Xanthomonas campestris pathovar campestris (Xcc), a Gram-negative yellow-pigmented pathogenic bacterium that causes black rot, one of the major worldwide diseases of cruciferous crops. The protein consists of 220 amino acids and its structure has been determined to 1.6 A resolution using the multi-wavelength anomalous dispersion (MAD) method. Although it has very low sequence identity to protein sequences in the PDB (less than 20%), the determined structure nevertheless shows that it belongs to the superfamily of serine alpha/beta-hydrolases, with an active site that is fully accessible to solvent owing to the absence of a lid domain. Modelling studies with the serine esterase inhibitor E600 indicate that XC6422 adopts a conserved Ser-His-Asp catalytic triad common to this superfamily and has a preformed oxyanion hole for catalytic activation. These structural features suggest that XC6422 is most likely to be a hydrolase active on a soluble ester or a small lipid. An extra strand preceding the first beta-strand in the canonical alpha/beta-hydrolase fold leads to extensive subunit interactions between XC6422 monomers, which may explain why XC6422 crystals of good diffraction quality can grow to dimensions of up to 1.5 mm in a few days.
