Cloning and sequencing of a cDNA encoding a copper-zinc superoxide dismutase enzyme from the marine yeast Debaryomyces hansenii

Marine enzymes: Classification and application in various industries

Oceans are regarded as a plentiful and sustainable source of biological compounds. Enzymes are a group of marine biomaterials that have recently drawn more attention because they are produced in harsh environmental conditions such as high salinity, extensive pH, a wide temperature range, and high pressure. Hence, marine-derived enzymes are capable of exhibiting remarkable properties due to their unique composition. In this review, we overviewed and discussed characteristics of marine enzymes as well as the sources of marine enzymes, ranging from primitive organisms to vertebrates, and presented the importance, advantages, and challenges of using marine enzymes with a summary of their applications in a variety of industries. Current biotechnological advancements need the study of novel marine enzymes that could be applied in a variety of ways. Resources of marine enzyme can benefit greatly for biotechnological applications duo to their biocompatible, ecofriendly and high effectiveness. It is beneficial to use the unique characteristics offered by marine enzymes to either develop new processes and products or improve existing ones. As a result, marine-derived enzymes have promising potential and are an excellent candidate for a variety of biotechnology applications and a future rise in the use of marine enzymes is to be anticipated.

Bio-products produced by marine yeasts and their potential applications

It has been well documented that the yeasts isolated from different marine environments are so versatile that they can produce various fine chemicals, enzymes, bioactive substances, single cell protein and nanoparticles. Many genes related to the biosynthesis and regulation of these functional biomolecules have been cloned, expressed and characterized. All these functional biomolecules have a variety of applications in industries of food, chemical, agricultural, biofuel, cosmetics and pharmacy. In this review, a summary will be given about these functional biomolecules and their producers of the marine yeasts as well as some related genes in order to draw an outline about necessity for further exploitation of marine yeasts and their bio-products for industrial applications.

Expression of Cu, Zn-superoxide dismutase gene from Saccharomyces cerevisiae in Pichia pastoris and its resistance to oxidative stress

The gene for the Cu, Zn-superoxide dismutase (SOD) from the yeast Saccharomyces cerevisiae was cloned, characterized, and overexpressed in the methylotrophic Pichia pastoris. The sod gene sequence obtained is 465 bp and encodes 154 amino acid residues. The sod gene sequence was cloned into the pPIC9K vector, yielding pAB22. The linearized pAB22 DNA, digested with restriction enzyme SacI, was transformed into the genome of the GS115 strain of the yeast P. pastoris. The SOD was purified from the cultured yeast by ammonium sulfate precipitation and DEAE-cellulose column chromatography. This relatively simple purification method produced a single band on analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The overexpressed SOD protein was shown to have immunologically biologic activity and to be enzymatically active. The yeast overexpressing Cu, Zn- SOD appeared to be more resistant to oxidative stress such as paraquat, menadione, and heat shock.

A new approach to the production of the recombinant SOD protein by methylotrophic Pichia pastoris

The gene for the copper, zinc-superoxide dismutase (SOD) from the yeast Saccharomyces cerevisiae was cloned, characterized, and overexpressed in the methylotrophic Pichia pastoris. The sod gene sequence obtained is 465 bp and encodes 154 amino acid residues. The sod gene sequence was cloned into the pPIC9K vector, yielding pAB22. The linearized pAB22 DNA, digested with restriction enzyme SacI, was transformed into the genome of the GS115 strain of yeast P. pastoris. The overexpressed SOD protein was shown to have immunologically biological activity and to be enzymatically active. The SOD protein was purified from the cultured yeast by ammonium sulfate precipitation and diethylaminoethyl-cellulose column chromatography. This relatively simple purification method produced a single band on analysis by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), which indicated that the SOD protein obtained attained to higher purity and specific activity.

Cloning and functional characterization of the copper/zinc superoxide dismutase gene from the heavy-metal-tolerant yeast Cryptococcus liquefaciens strain N6

The deep-sea yeast Cryptococcus liquefaciens strain N6 possesses high superoxide dismutase (SOD) activity and a high tolerance toward metal ions. To clarify the relationship between metal tolerance and SOD activity in this strain, we cloned the Cu/Zn SOD gene. This gene (Cl-SOD1) consists of 471 bp encoding 157 amino acids; the associated protein had 59.9-76.7% identity with Cu/Zn SOD proteins of other yeast species. The highest identity corresponded to Cryptococcus gattii (76.7%). Cl-SOD1 expression in the sod1 mutant of Saccharomyces cerevisiae revealed that this SOD protein was functional in S. cerevisiae. The Cl-SOD1 protein possessed approximately fourfold greater activity than S. cerevisiae SOD1 (Sc-SOD1) at 30 degrees C. The amount of Cl-SOD1 mRNA in strain N6 increased in the presence of copper ion. However, the level of this transcript was not dependent on an increase in copper ion concentration and did not correlate well with changes in the amount of Cu/Zn SOD protein. This result suggests that strain N6 possesses other Cu/Zn SOD genes induced in a manner different from Cl-SOD1 as found in Candida albicans, or that the Cl-SOD1 gene undergoes posttranscriptional regulation upon increase of copper ion.

Cu,Zn superoxide dismutase in Rhodotorula and Udeniomyces spp. isolated from sea water: cloning and sequencing the encoding region

The gene encoding the copper-zinc superoxide dismutase enzyme (SODC or Cu,Zn-SOD) has been cloned from several species of higher eukaryotes, but superoxide dismutase genes from moulds and yeast have not been studied extensively. Only 15 nucleotide sequences have been reported in the SwissProt, EMBL and GenBank data libraries. In general the presence of Cu,Zn-SOD in cytosol, as well as Mn-SOD in the mitochondrial matrix of yeast, has been accepted. The absence of Cu,Zn-SOD in a pigmented yeast has been accepted as a general rule. Some authors suggest that the absence of Cu,Zn-SOD in pigmented yeast is complemented by the presence of carotenoproteins that act as an extra mitochondrial antioxidant. In this report, we found that the absence of SODC is not a rule for pigmented yeast: Udeniomyces puniceus expresses an active SODC which responds to Cu(2+) induction, as has been reported previously for non-pigmented yeast. The encoding region of the sod1 gene was cloned from three species of pigmented marine yeast thorough genomic DNA PCR amplification. Fragments of 485-487 nucleotides were obtained, which contain information for theoretical products of 153-154 amino acids. In Rhodotorula mucilaginosa the deduced amino acid sequence shows that insertion of three bases (C(112), A(149) and C(166)) generates a stop codon at position 123 (TGA). For Rhodotorula graminis a single change (T for A) generates a stop codon at position 298. For both species, this non-transcription of encoding sequence correlates with the absence of peptides or active proteins in cell homogenates. For U. puniceus, the cloned nucleotide sequence contains all necessary information to produce a functional protein, which correlates with activity detected in cell homogenates, both under normal conditions and by copper induction experiments. Finally, we clearly showed that the key factor in protection against oxidative stress on pigmented yeast is related not only to the presence of protective pigments but also to their amounts and spectra, as well as the presence and activity of SODC.

Cloning and sequencing the genomic encoding region of copper-zinc superoxide dismutase enzyme from several marine strains of the genus Debaryomyces (Lodder & Kreger-van Rij)

Copper-zinc superoxide dismutase (SODC) is a cytosolic enzyme which catalyses the dismutation of the superoxide radical. Due to its physiological importance, the encoding genes have been cloned from several species of higher eukaryotes. However, genes from moulds and yeast have not been studied extensively. In this paper, the encoding region of this gene (sod1) has been cloned from several strains of marine yeast belonging to the genus Debaryomyces (dvv sod1, dvy sod1 and dh sod1-61) through genomic DNA-PCR amplification. Fragments of 480-486 nucleotides were obtained, which contain information for products of 153-156 amino acids with calculated molecular masses of 15.8-16.6 kDa. The deduced amino acid sequence shows that D. vanrijiae enzymes present three additional amino acids not closely related to the active site conformation. In addition, in D. vanrijiae var. vanrijiae (strain 020), one histidine residue is apparently replaced by a proline; the incidence and function of other aromatic or heterocyclic amino acids is discussed. Homology and phylogenetic trees were constructed from amino-acid sequence multi-alignment analyses; the interrelationships among fungi are discussed. The sod-1 sequences reported in this paper were deposited in the public data library of the NCBI under Accession Nos AF301019, AF327449 and AF327448.

A novel Cu,Zn superoxide dismutase from the fungal strain Humicola lutea 110: isolation and physico-chemical characterization

The fungal strain Humicola lutea 110 produces a mangan- and a copper zinc-containing superoxide dismutases (SOD). In this study, the purification, N-terminal sequence and spectroscopic properties of the new Cu,Zn SOD are described. The preparation of the pure metalloenzyme was achieved via treatment of the strain with acetone followed by gel and ion exchange chromatography. The protein consists of 302 amino acid residues and has a molecular mass of approximately 32 kDa, as determined by PAG electrophoresis and 3100 U mg-1 protein-specific activity. It is a dimeric enzyme with two identical subunits of 15,950 Da, as indicated by SDS-PAGE, mass spectroscopic and amino acid analysis. The N-terminal sequence analysis of the Cu,Zn SOD from the fungal strain revealed a high degree of structural homology with enzymes from other eukaryotic sources. Conformational stability and reversibility of unfolding of the dimeric enzyme were determined by fluorescence and circular dichroism (CD) spectroscopy. The critical temperature of deviation from linearity (Tc) of the Arrhenius plot ln (Q-1(-1)) vs. 1/T was calculated to be 68 degrees C and the respective activation energy for the thermal deactivation of the excited indole chromophores is 42 kcal mol-1. The melting temperatures (Tm) were determined by CD measurements to be 69 degrees C for the holo- and 61 degrees C for the apo-enzyme. The fluorescence emission of the Cu,Zn SOD is dominated by 'buried' tryptophyl chromophores. Removal of the copper-dioxygen system from the active site caused a 4-fold increase of the fluorescence quantum yield and a 10 nm shift of the emission maximum position towards higher wavelength.

Copper-zinc superoxide dismutase from the marine yeast Debaryomyces hansenii

We have isolated the cytosolic form of Cu-Zn superoxide dismutase (SOD) from the marine yeast Debaryomyces hansenii. This enzyme has a subunit mass of 18 kDa. The preparation was found to be heterogeneous by IF electrophoresis with two pI ranges: 5.14-4.0 and 1.6-1.8. The enzyme preparation had a remarkably strong stability at pH 6.0-7.0, surviving boiling for 10 min without losing more than 60% of activity. On Western blots, this enzyme was recognized by antibodies raised in rabbits against D. hansenii extracts, while only a weak cross-reaction could be detected using antibodies generated against either Saccharomyces cerevisiae or bovine erythrocyte Cu-Zn SODs. In sequencing analysis, a peptide obtained by trypsin digestion was found to have 85% identity to the S. cerevisiae Cu-Zn SOD.