Clade Of Enzymes Research Articles

Functional biology and biotechnology of thermophilic viruses.

Viruses have developed sophisticated biochemical and genetic mechanisms to manipulate and exploit their hosts. Enzymes derived from viruses have been essential research tools since the first days of molecular biology. However, most viral enzymes that have been commercialized are derived from a small number of cultivated viruses, which is remarkable considering the extraordinary diversity and abundance of viruses revealed by metagenomic analysis. Given the explosion of new enzymatic reagents derived from thermophilic prokaryotes over the past 40 years, those obtained from thermophilic viruses should be equally potent tools. This review discusses the still-limited state of the art regarding the functional biology and biotechnology of thermophilic viruses with a focus on DNA polymerases, ligases, endolysins, and coat proteins. Functional analysis of DNA polymerases and primase-polymerases from phages infecting Thermus, Aquificaceae, and Nitratiruptor has revealed new clades of enzymes with strong proofreading and reverse transcriptase capabilities. Thermophilic RNA ligase 1 homologs have been characterized from Rhodothermus and Thermus phages, with both commercialized for circularization of single-stranded templates. Endolysins from phages infecting Thermus, Meiothermus, and Geobacillus have shown high stability and unusually broad lytic activity against Gram-negative and Gram-positive bacteria, making them targets for commercialization as antimicrobials. Coat proteins from thermophilic viruses infecting Sulfolobales and Thermus strains have been characterized, with diverse potential applications as molecular shuttles. To gauge the scale of untapped resources for these proteins, we also document over 20,000 genes encoded by uncultivated viral genomes from high-temperature environments that encode DNA polymerase, ligase, endolysin, or coat protein domains.

The evolution of substrate specificity-associated residues and Ca(2+) -binding motifs in EF-hand-containing type II NAD(P)H dehydrogenases.

Most eukaryotic organisms, except some animal clades, have mitochondrial alternative electron transport enzymes that allow respiration to bypass the energy coupling in oxidative phosphorylation. The energy bypass enzymes in plants include the external type II NAD(P)H dehydrogenases (DHs) of the NDB family, which are characterized by an EF-hand domain for Ca(2+) binding. Here we investigate these plant enzymes by combining molecular modeling with evolutionary analysis. Molecular modeling of the Arabidopsis thaliana AtNDB1 with the yeast ScNDI1 as template revealed distinct similarities in the core catalytic parts, and highlighted the interaction between the pyridine nucleotide and residues correlating with NAD(P)H substrate specificity. The EF-hand domain of AtNDB1 has no counterpart in ScNDI1, and was instead modeled with Ca(2+) -binding signal transducer proteins. Combined models displayed a proximity of the AtNDB1 EF-hand domain to the substrate entrance side of the catalytic part. Evolutionary analysis of the eukaryotic NDB-type proteins revealed ancient and recent reversions between the motif observed in proteins specific for NADH (acidic type) and NADPH (non-acidic type), and that the clade of enzymes with acidic motifs in angiosperms derives from non-acidic-motif NDB-type proteins present in basal plants, fungi and protists. The results suggest that Ca(2+) -dependent external NADPH oxidation is an ancient process, indicating that it has a fundamental importance for eukaryotic cellular redox metabolism. In contrast, the external NADH DHs in plants are products of a recent expansion, mirroring the expansion of the alternative oxidase family.

Identification and Analysis of the SET-Domain Family in Silkworm, Bombyx mori.

As an important economic insect, Bombyx mori is also a useful model organism for lepidopteran insect. SET-domain-containing proteins belong to a group of enzymes named after a common domain that utilizes the cofactor S-adenosyl-L-methionine (SAM) to achieve methylation of its substrates. Many SET-domain-containing proteins have been shown to display catalytic activity towards particular lysine residues on histones, but emerging evidence also indicates that various nonhistone proteins are specifically targeted by this clade of enzymes. To explore their diverse functions of SET-domain superfamily in insect, we identified, cloned, and analyzed the SET-domains proteins in silkworm, Bombyx mori. Firstly, 24 genes containing SET domain from silkworm genome were characterized and 17 of them belonged to six subfamilies of SUV39, SET1, SET2, SUV4-20, EZ, and SMYD. Secondly, SET domains of silkworm SET-domain family were intraspecifically and interspecifically conserved, especially for the catalytic core “NHSC” motif, substrate binding site, and catalytic site in the SET domain. Lastly, further analyses indicated that silkworm SET-domain gene BmSu(var)3-9 owned different characterization and expression profiles compared to other invertebrates. Overall, our results provide a new insight into the functional and evolutionary features of SET-domain family.