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PubMed2026

Genomic prospecting and biochemical characterization of a novel thermostable 3-quinuclidinone reductase from hot spring metagenomes for efficient biocatalysis.

This study presents the discovery and characterization of a novel thermophilic 3-quinuclidinone reductase (ScQR) identified through metagenomic mining of hot spring environments. ScQR, a member of the short-chain dehydrogenase/reductase (SDR) superfamily, was heterologously expressed in Escherichia coli, and its catalytic properties were systematically characterized. The enzyme demonstrates exceptional thermal stability, retaining 86% of its activity after 48 hours at 70°C. Furthermore, K+ and Mg²+ ions significantly enhanced ScQR's activity at specific concentrations. Structural analysis revealed that ScQR adopts a typical SDR fold with a conserved catalytic triad (S141-Y155-K159), and it is NAD(H) dependent. Enzyme assays indicated that ScQR is highly stereoselective for (R)-3-quinuclidinol, with no activity against its enantiomer, (S)-3-quinuclidinol. The enzyme exhibits optimal activity at pH 9 and 85°C, making it a promising candidate for industrial applications requiring high thermal stability. Molecular dynamics simulations further revealed that ScQR preserves global structural integrity up to 360 K, whereas higher temperatures induce destabilization, predominantly in the C-terminal region and residues 95-100. In addition, structure-guided computational design enabled by LigandMPNN and UniKP yielded three ScQR variants with improved substrate affinity and catalytic efficiency while maintaining the overall fold and function. This work underscores the power of metagenomics with structure-driven protein design in discovering novel enzymes with unique catalytic properties from extreme environments and establishes ScQR as a promising biocatalyst for biotechnological and pharmaceutical applications.IMPORTANCEThis study reports the discovery of ScQR, a novel thermophilic 3-quinuclidinone reductase identified via metagenomic mining. ScQR represents one of the most heat-resistant members of the SDR superfamily discovered to date, maintaining 86% activity after 48 hours at 70°C. These findings establish ScQR as a robust biocatalyst for high-temperature pharmaceutical applications and demonstrate a scalable workflow for optimizing enzymes from extreme environments, offering significant value to the fields of biocatalysis and protein engineering.

computational design↗

PubMed1990

16S rRNA sequences reveal numerous uncultured microorganisms in a natural community.

Microbiologists have been constrained in their efforts to describe the compositions of natural microbial communities using traditional methods. Few microorganisms have sufficiently distinctive morphology to be recognized by microscopy. Culture-dependent methods are biased, as a microorganism can be cultivated only after its physiological niche is perceived and duplicated experimentally. It is therefore widely believed that fewer than 20% of the extant microorganisms have been discovered, and that culture methods are inadequate for studying microbial community composition. In view of the physiological and phylogenetic diversity among microorganisms, speculation that 80% or more of microbes remain undiscovered raises the question of how well we know the Earth's biota and its biochemical potential. We have performed a culture-independent analysis of the composition of a well-studied hot spring microbial community, using a common but distinctive cellular component, 16S ribosomal RNA. Our results confirm speculations about the diversity of uncultured microorganisms it contains.

Base Sequence↗

PubMed1992

Archaea in coastal marine environments.

Archaea (archaebacteria) are a phenotypically diverse group of microorganisms that share a common evolutionary history. There are four general phenotypic groups of archaea: the methanogens, the extreme halophiles, the sulfate-reducing archaea, and the extreme thermophiles. In the marine environment, archaeal habitats are generally limited to shallow or deep-sea anaerobic sediments (free-living and endosymbiotic methanogens), hot springs or deep-sea hydrothermal vents (methanogens, sulfate reducers, and extreme thermophiles), and highly saline land-locked seas (halophiles). This report provides evidence for the widespread occurrence of unusual archaea in oxygenated coastal surface waters of North America. Quantitative estimates indicated that up to 2% of the total ribosomal RNA extracted from coastal bacterioplankton assemblages was archaeal. Archaeal small-subunit ribosomal RNA-encoding DNAs (rDNAs) were cloned from mixed bacterioplankton populations collected at geographically distant sampling sites. Phylogenetic and nucleotide signature analyses of these cloned rDNAs revealed the presence of two lineages of archaea, each sharing the diagnostic signatures and structural features previously established for the domain Archaea. Both of these lineages were found in bacterioplankton populations collected off the east and west coasts of North America. The abundance and distribution of these archaea in oxic coastal surface waters suggests that these microorganisms represent undescribed physiological types of archaea, which reside and compete with aerobic, mesophilic eubacteria in marine coastal environments.

Animals↗

PubMed2025

Mining thermophile photosynthesis genes: a synthetic operon expressing Chloroflexota species reaction center genes in Rhodobacter sphaeroides.

Photosynthesis is the foundation of the vast majority of life systems, and therefore the most important bioenergetic process on earth, and the greatest diversity in photosynthetic systems are found in microorganisms. However, understanding of the biophysical and biochemical processes that transduce light to chemical energy has derived from the relatively small subset of proteins from microbes that are amenable to cultivation, in contrast to the huge number of microbial DNA sequences encoding proteins that catalyze the initial photochemical reactions that has been deposited in databases, such as from metagenomics. We describe the use of a Rhodobacter sphaeroides laboratory strain for expression of heterologous photosynthesis genes to demonstrate the feasibility of mining this resource, focusing on hot spring Chloroflexota gene sequences. Using a synthetic operon of genes, we produced a photochemically active complex of reaction center proteins in our biological system. We also present bioinformatic analyses of anoxygenic type II reaction center sequences from metagenomic samples collected from hot (42-90° C) springs available through the JGI IMG database, to generate a resource of diverse sequences that potentially are adapted to photosynthesis at such temperatures. These data provide a view into the natural diversity of anoxygenic photosynthesis, through a lens focused on high-temperature environments. The approach we took to express such genes can be applied for potential biotechnology purposes as well as for studies of fundamental catalytic properties of these heretofore inaccessible protein complexes.

Chloroflexota↗