Delta53betahyd

Delta53betahyd is a protein first identified in 2018 during a metagenomic survey of hydrothermal vent sediments at the Mid-Atlantic Ridge. The protein is encoded by the del53b gene, which is located on a single‑chromosome plasmid in the deep‑sea bacterium Marinobacter hydrothermalis. Sequence analysis shows that Delta53betahyd is composed of 457 amino acids and contains two distinct domains: a N‑terminal Δ53 domain (residues 1–155) that shares 38 % identity with the regulatory domain of bacterial two‑component systems, and a C‑terminal beta‑hydrophilic domain (residues 156–457) that is characteristic of beta‑hydrolases. The calculated molecular weight is 50.2 kDa and the isoelectric point is 6.8.

Functional assays indicate that Delta53betahyd acts as an esterase that preferentially hydrolyzes long‑chain fatty acid methyl esters, with a catalytic efficiency (k_cat/K_M) of 1.2 × 10⁵ M⁻¹ s⁻¹ for C₁₈:₀. Kinetic studies with site‑directed mutagenesis identified Asp198 and His249 as essential catalytic residues. The protein is expressed at high levels in E. coli BL21(DE3) when induced with 0.5 mM IPTG, and can be purified to >95 % homogeneity by Ni²⁺ affinity chromatography followed by size‑exclusion chromatography, yielding an oligomeric state of a dimer in solution.

Delta53betahyd has been proposed as a candidate for biotechnological applications in the biodiesel industry, where its activity can accelerate the hydrolysis of biodiesel by-products. Limited structural data are available; cryo‑EM reconstruction at 3.8 Å resolution has revealed a pocket surrounding the catalytic dyad that may accommodate lipid substrates. Further research is required to determine the physiological role of Delta53betahyd in its native habitat and its potential utility in industrial settings.