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Esterase
About: Esterase is a research topic. Over the lifetime, 7622 publications have been published within this topic receiving 168270 citations.
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TL;DR: This report describes the activity of a protein encoded by gene lysB from the mycobacteriophage Ms6, believed to be the first description of aprotein with lipolytic activity encoded within a bacteriophages.
Abstract: dsDNA bacteriophages use the dual system endolysin-holin to achieve lysis of their bacterial host. In addition to these two essential genes, some bacteriophages encode additional proteins within their lysis module. In this report, we describe the activity of a protein encoded by gene lysB from the mycobacteriophage Ms6. lysB is localized within the lysis cassette, between the endolysin gene (lysA) and the holin gene (hol). Analysis of the deduced amino acid sequence of LysB revealed the presence of a conserved motif (Gly-Tyr-Ser-Gln-Gly) characteristic of enzymes with lipolytic activity. A blast search within the sequences of protein databases revealed significant similarities to other putative proteins that are encoded by mycobacteriophages only, indicating that LysB and those proteins may be specific to their mycobacterial hosts. A screening for His(6)-LysB activity on esterase and lipase substrates confirmed the lipolytic activity. Examination of the kinetic parameters of recombinant His(6)-LysB for the hydrolysis of p-nitrophenyl esters indicated that although this protein could use a wide range of chain length substrates (C(4)-C(18)), it presents a higher affinity for p-nitrophenyl esters of longer chain length (C(16) and C(18)). Using p-nitrophenyl butyrate as a substrate, the enzyme showed optimal activity at 23 degrees C and pH 7.5-8.0. Activity was increased in the presence of Ca(2+) and Mn(2+). To the best of our knowledge, this is the first description of a protein with lipolytic activity encoded within a bacteriophage.
59 citations
TL;DR: The structure of the catalytic domain of glucuronoyl esterase Cip2 from the fungus H. jecorina was determined and revealed the residues Ser278-His411-Glu301 present in a triad arrangement as the active site.
Abstract: The structure of the catalytic domain of glucuronoyl esterase Cip2 from the fungus H. jecorina was determined at a resolution of 1.9 A. This is the first structure of the newly established carbohydrate esterase family 15. The structure has revealed the residues Ser278-His411-Glu301 present in a triad arrangement as the active site. Ser278 is present in the novel consensus sequence GCSRXG reported earlier in the members of CE-15 family. The active site is exposed on the surface of the protein which has implications for the ability of the enzyme to hydrolyze ester bonds of large substrates. Efforts are underway to obtain crystals of Cip2_GE complexed with inhibitor and synthetic substrates. The activity of the glucuronoyl esterase could play a significant role in plant biomass degradation as its expected role is to separate the lignin from hemicelluloses by hydrolysis of the ester bond between 4-O-methyl-D-glucuronic acid moieties of glucuronoxylans and aromatic alcohols of lignin.
59 citations
59 citations
TL;DR: It is shown that loss of the elevated enzyme occurred simultaneously with loss of methylation at CCGG sites in the amplified DNA sequences, and although DNA methylation is closely correlated with expression of the amplified esterase genes during reversion, it may not be a factor in the reverse process.
59 citations
TL;DR: The onset of resistance is similar for both the xylanase and acetyl esterase enzymes, and both enzymes were completely inhibited by a degree of acetylation of 1.5 moles acetyl groups per mole anhydroxylose units at all enzyme loadings.
Abstract: The effect of the degree of acetylation on the enzymatic digestibility of acetylated xylans has been investigated. Oatspelts xylans were reacetylated to degrees of 0.26 to 1.67 moles acetyl groups per mole of anhydroxylose units. These acetylated samples were then used to study the effect of acetylation on the xylanase (EC 3.2.1.8) and acetyl esterase (EC 3.1.1.6) activities of a commercial Trichoderma reesei cellulase preparation. The enzymatic digestibility was dramatically affected by the degree of acetylation. The onset of resistance is similar for both the xylanase and acetyl esterase enzymes, and both enzymes were completely inhibited by a degree of acetylation of 1.5 moles acetyl groups per mole anhydroxylose units at all enzyme loadings.
59 citations