A new extracellular κ-carrageenase, namely CgkP, 34.0 kDa in molecular weight, was purified from Pseudoalteromonas sp. QY203. CgkP showed relatively high activity at acidities ranging from pH6.0 to pH9.0 and temperat...A new extracellular κ-carrageenase, namely CgkP, 34.0 kDa in molecular weight, was purified from Pseudoalteromonas sp. QY203. CgkP showed relatively high activity at acidities ranging from pH6.0 to pH9.0 and temperatures ranging from 30℃ to 50℃ with the highest activity at 45℃ and pH7.2. Sodium chloride increased its activity markedly, and KC1 increased its activity slightly. The divalent and trivalent metal ions including Cu^2＋, Ni^2＋, Zn^2＋, Mn^2＋, Al^3＋ and Fe^3＋ significantly inhibited its activity, while Mg^2＋ did not. CgkP remained 70% of original activity after being incubated at 40℃ for 48h, and remained 80% of the activity after being incubated at 45℃ for 1 h. It exhibited endo-κ-carrageenase activity, mainly depolymerizing the κ-carrageenan into disaccharide and tetrasaccharide. CgkP was more thermostable than most of previously reported κ-carrageenases with a potential of being used in industry.展开更多
kappa-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by kappa-carrageenase is safe and controllable. Therefore, kappa-carrageenases have captured more and more attentions. In...kappa-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by kappa-carrageenase is safe and controllable. Therefore, kappa-carrageenases have captured more and more attentions. In this study, a kappa-carrageenase encoding gene, cgkX, was cloned from Pseudoalteromonas sp. QY203 with degenerate and inverse PCR. It comprised an ORF of 1194 bp in length, encoding a protein with 397 amino acid residues. CgkX is a new member of glycoside hydrolase family 16. The deduced amino acid sequence shared a high similarity with CgkX of Pseudoalteromonas kappa-carrageenase; however, the recombinant CgkX showed different biochemical characteristics. The recombinant enzyme was most active at pH 7.0 and 55A degrees C in the presence of 300 mmol L-1 NaCl. It was stable in a broad range of acidity ranging from pH 3.0 to pH 10.0 when temperature was below 40A degrees C. More than 80% of its activity was maintained after being incubated at pH 3.6-10.0 and 4A degrees C for 24 h. CgkX retained more than 90% of activity after being incubated at 40A degrees C for 1 h. EDTA and SDS (1 mmol L-1) did not inhibit its activity. CgkX hydrolyzed kappa-carrageenan into disaccharide and tetrasaccharide as an endo-cleaver. All these characteristics demonstrated that CgkX is applicable to both kappa-carrageenan oligosaccharide production and kappa-carrageenase structure-function research.展开更多
Pseudoalteromonas,with a ubiquitous distribution,is one of the most abundant marine bacterial genera.It is especially abundant in the deep sea and polar seas,where it has been found to have a broad metabolic capacity ...Pseudoalteromonas,with a ubiquitous distribution,is one of the most abundant marine bacterial genera.It is especially abundant in the deep sea and polar seas,where it has been found to have a broad metabolic capacity and unique co-existence strategies with other organisms.However,only a few Pseudoalteromonas phages have so far been isolated and investigated and their genomic diversity and distribution patterns are still unclear.Here,the genomes,taxonomic features and distribution patterns of Pseudoalteromonas phages are systematically analyzed,based on the microbial and viral genomes and metagenome datasets.A total of 143 complete or nearly complete Pseudoalteromonas-associated phage genomes(PSAPGs)were identifed,including 34 Pseudoalteromonas phage isolates,24 proviruses,and 85 Pseudoalteromonas-associated uncultured viral genomes(UViGs);these were assigned to 47 viral clusters at the genus level.Many integrated proviruses(n=24)and flamentous phages were detected(n=32),suggesting the prevalence of viral lysogenic life cycle in Pseudoalteromonas.PSAPGs encoded 66 types of 249 potential auxiliary metabolic genes(AMGs)relating to peptidases and nucleotide metabolism.They may also participate in marine biogeochemical cycles through the manipulation of the metabolism of their hosts,especially in the phosphorus and sulfur cycles.Siphoviral and flamentous PSAPGs were the predominant viral lineages found in polar areas,while some myoviral and siphoviral PSAPGs encoding transposase were more abundant in the deep sea.This study has expanded our understanding of the taxonomy,phylogenetic and ecological scope of marine Pseudoalteromonas phages and deepens our knowledge of viral impacts on Pseudoalteromonas.It will provide a baseline for the study of interactions between phages and Pseudoalteromonas in the ocean.展开更多
基金supported by National Science Foundation of China (31000361 and 31070712)Program for Changjiang Scholars and Innovative Research Team in University (IRT0944)+1 种基金Special Fund for Marine Scientific Research in the Public Interest (201005024)the Fundamental Research Funds for the Central Universities(201013008)
文摘A new extracellular κ-carrageenase, namely CgkP, 34.0 kDa in molecular weight, was purified from Pseudoalteromonas sp. QY203. CgkP showed relatively high activity at acidities ranging from pH6.0 to pH9.0 and temperatures ranging from 30℃ to 50℃ with the highest activity at 45℃ and pH7.2. Sodium chloride increased its activity markedly, and KC1 increased its activity slightly. The divalent and trivalent metal ions including Cu^2＋, Ni^2＋, Zn^2＋, Mn^2＋, Al^3＋ and Fe^3＋ significantly inhibited its activity, while Mg^2＋ did not. CgkP remained 70% of original activity after being incubated at 40℃ for 48h, and remained 80% of the activity after being incubated at 45℃ for 1 h. It exhibited endo-κ-carrageenase activity, mainly depolymerizing the κ-carrageenan into disaccharide and tetrasaccharide. CgkP was more thermostable than most of previously reported κ-carrageenases with a potential of being used in industry.
基金supported by the National High-Tech R&D Program(No.2011AA090703)the National Natural Science Foundation of China(No.31070712)the Special Fund for Marine Scientific Research in the Public Interest(Nos.201105027 and 201005024)
文摘kappa-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by kappa-carrageenase is safe and controllable. Therefore, kappa-carrageenases have captured more and more attentions. In this study, a kappa-carrageenase encoding gene, cgkX, was cloned from Pseudoalteromonas sp. QY203 with degenerate and inverse PCR. It comprised an ORF of 1194 bp in length, encoding a protein with 397 amino acid residues. CgkX is a new member of glycoside hydrolase family 16. The deduced amino acid sequence shared a high similarity with CgkX of Pseudoalteromonas kappa-carrageenase; however, the recombinant CgkX showed different biochemical characteristics. The recombinant enzyme was most active at pH 7.0 and 55A degrees C in the presence of 300 mmol L-1 NaCl. It was stable in a broad range of acidity ranging from pH 3.0 to pH 10.0 when temperature was below 40A degrees C. More than 80% of its activity was maintained after being incubated at pH 3.6-10.0 and 4A degrees C for 24 h. CgkX retained more than 90% of activity after being incubated at 40A degrees C for 1 h. EDTA and SDS (1 mmol L-1) did not inhibit its activity. CgkX hydrolyzed kappa-carrageenan into disaccharide and tetrasaccharide as an endo-cleaver. All these characteristics demonstrated that CgkX is applicable to both kappa-carrageenan oligosaccharide production and kappa-carrageenase structure-function research.
基金This work was supported by the Laoshan Laboratory(No.LSKJ202203201)National Key Research and Development Program of China(2022YFC2807500)+1 种基金Natural Science Foundation of China(No.41976117,42120104006,42176111 and 42188102)and the Fundamental Research Funds for the Central Universities(202172002,201812002,202072001 and Andrew McMinn).
文摘Pseudoalteromonas,with a ubiquitous distribution,is one of the most abundant marine bacterial genera.It is especially abundant in the deep sea and polar seas,where it has been found to have a broad metabolic capacity and unique co-existence strategies with other organisms.However,only a few Pseudoalteromonas phages have so far been isolated and investigated and their genomic diversity and distribution patterns are still unclear.Here,the genomes,taxonomic features and distribution patterns of Pseudoalteromonas phages are systematically analyzed,based on the microbial and viral genomes and metagenome datasets.A total of 143 complete or nearly complete Pseudoalteromonas-associated phage genomes(PSAPGs)were identifed,including 34 Pseudoalteromonas phage isolates,24 proviruses,and 85 Pseudoalteromonas-associated uncultured viral genomes(UViGs);these were assigned to 47 viral clusters at the genus level.Many integrated proviruses(n=24)and flamentous phages were detected(n=32),suggesting the prevalence of viral lysogenic life cycle in Pseudoalteromonas.PSAPGs encoded 66 types of 249 potential auxiliary metabolic genes(AMGs)relating to peptidases and nucleotide metabolism.They may also participate in marine biogeochemical cycles through the manipulation of the metabolism of their hosts,especially in the phosphorus and sulfur cycles.Siphoviral and flamentous PSAPGs were the predominant viral lineages found in polar areas,while some myoviral and siphoviral PSAPGs encoding transposase were more abundant in the deep sea.This study has expanded our understanding of the taxonomy,phylogenetic and ecological scope of marine Pseudoalteromonas phages and deepens our knowledge of viral impacts on Pseudoalteromonas.It will provide a baseline for the study of interactions between phages and Pseudoalteromonas in the ocean.
